☺Myricetin, quercetin and catechin-gallate inhibit glucose uptake in isolated rat adipocytes. PDF file
Pablo STROBEL*, Claudio ALLARD*†, Tomás PEREZ-ACLE†, Rosario CALDERON*, Rebeca ALDUNATE* and Federico LEIGHTON*
*Molecular Nutrition Laboratory and †Center for Genomics and Bioinformatics, Faculty of Biological Sciences, Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
Biochemical Journal Immediate Publication. Published on 7 Oct 2004 as manuscript BJ20040703
SYNOPSIS: The facilitative glucose transporter GLUT4 mediates insulin-stimulated glucose uptake in adipocytes and muscle, and the participation of GLUT4 in the pathogenesis of various clinical conditions associated to obesity, visceral fat accumulation and insulin resistance, has been proposed. Glucose uptake by some members of the GLUT family, mainly GLUT1, is inhibited by flavonoids, natural polyphenols present in fruits, vegetables and wine. Therefore, it is of interest to establish if these polyphenolic compounds present in the diet, known to be effective antioxidants, but also endowed with several other biological activities such as protein-tyrosine kinase inhibition, interfere with GLUT4 function. Here we show that three flavonoids, quercetin, myricetin and catechin-gallate, inhibit methylglucose uptake by adipocytes at a concentration range of 10-100 µM. These three flavonoids show a competitive pattern of inhibition, with Ki values of 16, 33.5, and 90 µM, respectively. In contrast, neither catechin nor Gallic acid inhibit methylglucose uptake. To obtain a better understanding of the interaction among GLUT4 and flavonoids, we have derived a GLUT4 3D molecular comparative model, using structural coordinates from a GLUT3 comparative model and a mechanosensitive ion channel (PDB:1MSL) solved by X-ray diffraction. On the whole, the experimental evidence and the in silico simulation data favor a transport inhibition mechanism in which flavonoids and GLUT4 interact directly, rather than a mechanism related to protein-tyrosine kinase and insulin signaling inhibition. Further, the results suggest that GLUT transporters are involved in flavonoid incorporation into cells.
Key Words: flavonoids, GLUT4, adipocytes, glucose transporter, comparative model, molecular dynamics
Orawan Khantamat, M.S., Wittaya Chaiwangyen, M.S., Porn-ngarm Limtrakul, Ph.D.
Department of Biochemistry, Faculty of Medicine, Chiang Mai University
Chiang Mai Med Bull 2004;43(2):45-56.
Abstract The 170 kDa plasma membrane, P-glycoprotein (Pgp), causes the efflux of chemotherapeutic drugs from cells and is believed to be an important mechanism in multidrug resistance (MDR) in human cancer. In this study, some well-know flavonoids from vegetables and fruit were tested for their potential ability to modulate the function of Pgp in the multidrug-resistant human cervical carcinoma cell line, KB-V1. The data demonstrated that kaempferol and daidzein stimulated vinblastine sensitivity of KB-V1 cells (P<0.05) and revealed that the inhibitory concentration at 50% growth (IC50) of vinblastine was decreased markedly in the presence of these flavonoids in a dose dependent manner. These flavonoids did not affect in wild type KB-3-1 cells, which lack Pgp. Kaempferol also increased the intracellular accumulation, and reduced the efflux of rhodamine 123 (Rh123), which is known to be a good substrate of Pgp in KB-V1 cells. These findings provide evidence that the flavonoid, i.e. kaempferol, could reverse the vinblastine resistant phenotype by inhibiting Pgp activity in KB-V1 cells, and the ability to affect the Pgp activity could be of relevance to the chemosensitization of this flavonoid towards anticancer drugs.
Keywords: Flavonoids, KB-V1 cells, P-glycoprotein, Multidrug resistance, Vinblastine, Rhodamine123
☺ Bioactive pyrones and flavonoids from Cryptocarya ashersoniana seedlings PDF file
Maria A. G. Ricardo, Márcio A. Andreo, Alberto J. Cavalheiro, Ian C. Gamboa, Vanderlan S. Bolzani, Dulce H. S. Silva* Instituto de Química, Universidade Estadual Paulista, CP. 359, Araraquara, CEP 14800-900, São Paulo, SP, Brazil
ARKIVOC 2004 (vi) 127-136
Abstract The bioassay directed fractionation of the EtOH extract from leaves of Cryptocarya ashersoniana seedlings led to the isolation of two flavonol glucosides: iso-quercitrin and hyperin, which exhibited free radical scavenging activity towards DPPH (IC50 34.4 µM and 32.7 µM, respectively) and were compared to standard compounds rutin (IC50 27.0 µM) and catechin (IC50 41.4 µM). Investigation of extracts from the seedlings roots and stems afforded one antifungal styrylpyrone: goniothalamine, and two dihydropyrones: 6-propyl-5,6-dihydro-2-pyrone and the new 6-[(4’-ethyl-9’-oxabicyclo[3.3.1]non-6’-en-3’-yl)methyl]-5,6-dihydro-2H-pyran-2-one, which had its structure determined by detailed analysis of MS and NMR data, including 2D experiments. Keywords: Cryptocarya ashersoniana, Lauraceae, pyrone, flavonoid, antioxidant, free radical scavenger, DPPH.
☺ Selective effects of quercetin on the cell growth and antioxidant defense PDF file
system in normal versus transformed mouse hepatic cell lines
Young-Ok Sona, Kyung-Yeol Leea, Sung-Ho Kooka, Jeong-Chae Leeb, Jong-Ghee Kimb, Young-Mi Jeonb, Yong-Suk Janga,*
A Division of Biological Sciences and Research Center of Bioactive Materials, Chonbuk National University, Chonju 561-756, South Korea
b Laboratory of Cell Biology in Department of Orthodontics and Research Institute of Clinical Medicine, Chonbuk National University, Chonju 561-756, South Korea
European Journal of Pharmacology 502 (2004) 195– 204
Abstract: Quercetin is a dietary anticancer chemical that is capable of inducing apoptosis in tumor cells. However, little is known about its biological effect on nonmalignant cells, although the effect is one of the critical criteria to evaluate the clinical efficacy of the anticancer agent. In this study, we investigated the effects of quercetin on cell growth and apoptosis using embryonic normal hepatic cell line (BNL CL.2) and its SV40-transformed cell line (BNL SVA.8). We also evaluated the effects of quercetin on the antioxidant defense system in those cells. BNL SVA.8 cells were more sensitive to quercetin-mediated cytotoxicity than BNL CL.2 cells. In addition, the enzyme assays showed that quercetin actively stimulated the antioxidant defense systems including superoxide dismutase, catalase, glutathione, and glutathione reductase only in the BNL CL.2 cells. In particular, quercetin significantly reduced superoxide dismutase activity and increased the malonaldehyde content in BNL SV A.8 cells. These are thought to be closely related to quercetin-mediated apoptosis. Our findings suggest that quercetin is a dietary flavonoid that is capable of inducing selective growth inhibition and apoptosis in hepatic tumor cells, but not in normal cells.
Keywords: Quercetin; Hepatocyte; Selective growth inhibition; Apoptosis; Antioxidant defense system
☺Quantitative analysis of the flavonoids in raw propolis from northern Croatia* PDF file
IVAN KOSALEC1** MARINA BAKMAZ2 STJEPAN PEPELJNJAK1 SANDA VLADIMIR-KNE@EVI]3
1 Institute of Microbiology Faculty of Pharmacy and Biochemistry University of Zagreb HR-10000 Zagreb, Croatia
2 Analytical Laboratory Pharmacy »Zagreb« HR-10412 Rakov Potok, Croatia
3 Institute of Pharmacognosy Faculty of Pharmacy and Biochemistry University of Zagreb HR-10000 Zagreb, Croatia
Acta Pharm. 54 (2004) 65–72
Spectrometric analyses of flavonoids in twenty propolis samples, collected from ten different geographic localities in northern Croatia using two complementary methods, are reported. Flavones and flavonols were determined using aluminum chloride and expressed as quercetine equivalent while flavanones were determined using 2,4-dinitrophenylhydrazine and expressed as naringenin. Contents of flavones and flavonols were similar for most samples and ranged from 2 to 2.3%, except for one sample with a concentration of 1.3% and one sample in which it was not possible to detect flavones and flavonols. The content of flavanones in propolis samples is very variable. 55% of samples contained flavanones between 15 and 24% and 45% of samples between 4 and 14%. Total levels of flavonoids in raw propolis samples ranged between 5 and 26%; for the majority of samples (75%), the total level of flavonoids ranged between 15 and 25.9%. The high variability of flavanone concentration will affect the biological activity of propolis preparations.
Keywords: propolis, flavonoids, flavones, flavonols, flavanones, Croatia
☺REVERSING β-LACTAM ANTIBIOTIC RESISTANCE WITH SOME FLAVONOIDS IN GRAM-POSITIVE BACTERIA PDF file
Griangsak Eumkeb1* and Richards R. Michael E.2
Suranaree J. Sci. Technol. Vol. 11 No. 2; April-June 2004
Abstract: The antibacterial action of naturally occurring flavonoids was investigated. When combined amoxicillin with galangin 12.5 µg/ml, minimum inhibitory concentrations (MICs) of amoxicillin against twelve clinical isolates of resistant Staphylococcus aureus (S. aureus) and four isolates of methicillin-resistant S. aureus (MRSA) were reduced from an initial range of 2- > 250 µg/ml and 32- > 250 µg/ml to a range of < 0.25-2 µg/ml and < 0.25 µg/ml, respectively. Furthermore, six clinical isolates of ceftazidime-resistant S. aureus with MICs 32-250 µg/ml had their resistance to ceftazidime reversed by galangin 25 µg/ml to MICs of < 0.25 µg/ml. Viable counts showed that the killing of penicillin-resistant S. aureus cells by 10 and 50 µg/ml benzylpenicillin was potentiated by 25 µg/ml baicalin. Electronmicroscopy clearly showed that the combination of 25 µg/ml benzylpenicillin with 25 µg/ml galangin caused damage to the ultrastructures of MRSA cells. Enzymes assays indicated that galangin, tectochrysin and 6-chloro-7-methylflavone had inhibitory activity against β-lactamaseI from Bacillus cereus. Apigenin showed marked inhibitory activity against penicillinase type IV from Enterobacter cloacae. It was concluded that galangin, baicalin and tested flavonoids exhibited the potential to reverse bacterial resistance to β-lactam antibiotics against MRSA and other strains of β-lactam-resistant S. aureus.
Keywords: Methicillin-resistant S. aureus, traditional herbal remedies, antibacterial agents, reverse bacterial resistance, minimum inhibitory concentrations
Oleg Y. Borbulevych,1 Jerzy Jankun,1,2 Steven H. Selman,1,2 and Ewa Skrzypczak-Jankun1*
1Medical College of Ohio, Urology Research Center, Department of Urology, Toledo, Ohio
2Medical College of Ohio, Department of Physiology and Molecular Medicine, Toledo, Ohio
PROTEINS: Structure, Function, and Bioinformatics 54:13–19 (2004)
ABSTRACT: PUFA metabolites have a profound effect on inflammatory diseases and cancer progression. Blocking their production by inhibiting PUFA metabolizing enzymes (dioxygenases: cyclooxygenases and LOXs) might be a successful way to control and relieve such problems, if we learn to better understand their actions at a molecular level. Compounds with strong antioxidative and free radical scavenging properties, such as polyphenols, could be effective in blocking PUFA activities, and natural flavonoids possess such qualities. Quercetin belongs to the group of natural catecholic compounds and is known as a potent, competitive inhibitor of LOX. Structural analysis reveals that quercetin entrapped within LOX undergoes degradation, and the resulting compound has been identified by X-ray analysis as protocatechuic acid (3,4-dihydroxybenzoic acid) positioned near the iron site. Its C3-OH group points toward His523, C4-OH forms a hydrogen bond with OACfrom the enzyme’s C-terminus, and the carboxylic group is incorporated into the hydrogen bonding network of the active-site neighborhood via Gln514. This unexpected result, together with our previous observations concerning other polyphenols, yields new evidence about the metabolism of natural flavonoids. These compounds might be vulnerable to the co-oxidase activity of LOX, leading to enzymestimulated oxidative degradation, which results in an inhibitor of a lower molecular weight. Proteins
Key words: lipoxygenase; co-oxidase activity; lipoxygenase inhibitors; flavonoids; quercetin/metabolism/oxidative degradation
☺ Molecular imaging of the biological effects of quercetin and quercetin-rich foods PDF file
Jan Øivind Moskaug, Harald Carlsen, Mari Myhrstad, Rune Blomhoff∗
Institute for Nutrition Research, Faculty of Medicine, University of Oslo, P.O. Box 1046, Blindern, 0316 Oslo, Norway
Mechanisms of Ageing and Development 125 (2004) 315–324
Abstract: The human diet contains several thousands of organic plant molecules (i.e. phytochemicals), many of which have significant bioactivities. The specific physiological effects of these compounds are impossible to predict from in vitro studies using cell cultures and cell-free model systems. Nutrigenomics, which may be defined as the application of genomic tools to study the integrated effects of nutrients on gene regulation, however, holds great promise in increasing the understanding of how nutrients affect molecular events in an organism. Quercetin, a phytochemical belonging to the flavonoids, has antioxidant activities, inhibit protein kinases, inhibit DNA topoisomerases and regulate gene expression. The aim of the present review is to describe some of the many effects of quercetin, and how molecular imaging using transgenic reporter mice may serve as a tool to study the integrated influence of quercetin and other dietary phytochemicals on gene expression in vivo. We are using the bioluminescence emitted from firefly luciferase as the reporter since light originating from the inside of a cell or organism can be detected externally in an intact living organism. Molecular imaging using reporter models is therefore a unique technology to study the integrated effects of environmental insults and dietary substances on the influence of gene expression in disease development. We utilize these in vivo models to elucidate the role of various flavonoids, such as quercetin, for modulating gene expression related to oxidative stress and the antioxidant defence system.
Keywords: Phytochemicals; Flavonoids; Nutrigenomics; NF-kB; β-glutamylcysteine synthetase
☺ Role of flavonoids in the prevention of haematotoxicity due to chemotherapeutic agents PDF file
Mesbah Lahouel1, Jean Paul Fillastre2
1Laboratory of Pharmacology and Phytochemistry, Department of Biology. University of Jijel, 18000, Jijel, Algeria,
2Service of Nephrology, Hospital of Bois-Guillaume, 76031 Rouen, France
Haema 2004; 7(3): 313-320
Abstract. Flavonoids are polyphenols widely distributed and known to possess biological and pharmacological activities, including anti-inflammatory action against free radicals. Haematotoxicity is the main side-effect of chemotherapeutic agents. Therefore, the protection of chemotherapy toxicity by flavonoids is a new field in tumour therapy. Our study shows that oral administration of 100 mg/kg/daily over two weeks of flavonoids (diosmin, hesperidin, quercetin extracted from propolis and daflon®) before chemotherapy injection offers some protection against the haematotoxicity of doxorubicin (DOX), cyclophosphamide (CPM) or daunorubicin (DNR). Female wistar rats were injected with a single dose of 10 mg/kg ADR, 40 mg/kg DNR or were given 100 mg/kg CPM in a single dose. A second group received avonoids 100 mg/kg/daily before chemotherapy for two weeks. Blood samples were taken at different times: 3, 7, 14 and 28 days after the administration of chemotherapeutic agents. A haematological depletion was observed following treatment with all chemotherapy agents alone, in the first group of rats. The leukopoenia reached the level of 1.500 cells/ìl on day 2, and anaemia presented three weeks after treatment. A significant protection of chemotherapy haematotoxicity occurred after pre-treatment with flavonoids 100 mg/kg in all groups. We observed no significant difference between rats receiving the combination of flavonoids and chemotherapy and control group. These results suggest that flavonoids seem to offer protection against chemotherapy toxicity.
Key words: chemotherapeutic agents . flavonoids . rat . protection . toxicity
Ömer Coşkun1, Mehmet Kanter1, Ferah Armutçu2, Kurtuluş Çetin1, Betül Kaybolmaz1, Ömer Yazgan1.
Karaelmas University, Faculty of Medicine, Departments of Medical Histology-Embryology1 and Biochemistry2
Eur J Gen Med 2004; 1(3): 37-42
Free radicals have been reported to be responsible for many ailments including gastroduodenal ulcers. Recent studies demonstrated that quercetin (QE) has an antioxidant effects on injuries caused by various toxic agents in different experimental models. In our study, we examined anti-ulcerogen and antioxidant effects of quercetin on ethanol-induced gastric lesions in rats. QE was administered intraperitoneally (i.p.) 50 mg/kg. It was found that pretreatment with QE significantly reduced ethanol-induced gastric damage and malondialdehyde levels, and significantly increased antioxidant enzyme activities. We conclude that QE clearly has antioxidant properties and that the protective effect of QE against ethanol-induced gastric mucosal lesion, at least in part, depends upon the reduction in the lipid peroxidation and an increase in the activity of antioxidant enzymes.
Key words: Quercetin, ethanol, antioxidant enzymes, gastric damage, oxidative stress, rat.
Erica L. Campbella, Mary Chebibb, Graham A.R. Johnstona,*
aDepartment of Pharmacology, The University of Sydney, Sydney 2006, NSW, Australia
bFaculty of Pharmacy, The University of Sydney, Sydney 2006, NSW, Australia
Biochemical Pharmacology 68 (2004) 1631–1638
Abstract: The dietary flavonoids apigenin, genistein and (_)-epigallocatechin gallate (EGCG) inhibited the activation by GABA (40 mM) of recombinant human a1b2g2L GABAA receptors expressed in Xenopus laevis oocytes with IC50 values of 8, 30 and 15 mM, respectively. Apigenin and genistein also acted as GABA antagonists at flumazenil-insensitive a1b2 GABAA receptors, indicating that they were not acting as negative modulators through flumazenil-sensitive benzodiazepine sites on GABAA receptors. In addition to these GABAA antagonist effects, a novel second order modulatory action was found for apigenin and EGCG on the first order enhancement of GABA responses by diazepam. Apigenin (1 mM) and EGCG (0.1 mM) enhanced the modulatory action of diazepam (3 mM) on the activation by GABA (5 mM) of recombinant human a1b2g2L GABAA receptors by up to 22% and 52%, respectively. This was not found with genistein, nor was it observed with enhancement by allopregnanolone or pentobarbitone. Keywords: Apigenin; (_)-Epigallocatechin gallate; Genistein; GABAA receptors; Diazepam; Flavonoids; Modulation; Herbal medicine
Marica Medi}-[ari},** Ivona Jasprica, Asja Smol~i}-Bubalo, and Ana Mornar
Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kova~i}a 1, 10000 Zagreb, Croatia
Flavonoids are one of the largest groups of natural compounds known. They are supposed to have numerous physiological activities. There are many foods that contain flavonoids, but one of the most important sources of flavonoids is propolis. Besides flavonoids, phenolic acids are the main active substances of propolis. The list of uses and preparations of propolis is almost endless and demands an accurate analytical method to define the substances in this natural product. It can be easily analyzed by chromatographic methods, but before testing a new type of propolis it is opportune to optimize chromatographic conditions. The aim of this study is to optimize the chromatographic conditions in TLC of flavonoids and phenolic acids, as standard compounds that may be present in Croatian propolis. We compared 9 different mobile phases, using information theory and numerical taxonomy methods and applying the computer search program KT1, to find the most appropriate mobile phase, the optimal combination of two and three mobile phases for separation of standards.
Key words: flavonoids; phenolic acids; optimization; TLC; information theory; numerical taxonomy
☺Spectrophotometric Studies of the Interaction of Noble Metals PDF file
with Quercetin and Quercetin-5￠-Sulfonic Acid
Maria BALCERZAK,*† Maria KOPACZ,** Anna KOSIOREK,* Elzbieta SWIECICKA,* and Stanis¬aw KUS*
*Department of Analytical Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
**Department of Inorganic and Analytical Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, Poland
Results of some studies on the interaction of noble metals with quercetin (Q) and quercetin-5′-sulfonic acid (QSA), the compounds of flavonoid group, are presented. The reactions of chloride complexes of the metals: RuOHCl5 2–, PdCl42–,OsCl62–, PtCl62– and AuCl4– with both reagents were examined. The redox reactions of ruthenium and gold with Q and QSA have been identified. The reaction of the metals with both reagents results in the formation of the oxidized form of Q that exhibits maximum absorbance at 291 nm. Ruthenium and gold react with the examined reagents under similar conditions: 0.04 M HCl and 1 × 10–4 M Q (or QSA). The CH3OH + H2O (1:1) (Q) and pure aqueous (QSA) media can be used. The reaction of gold with Q is slow at room temperature. It can be accelerated by heating the solution being examined. The reaction proceeds significantly faster when the water-soluble sulfonic derivative of quercetin, quercetin-5′-sulfonic acid, is used as a reagent. The new species formed can make the basis of spectrophotometric methods for the determination of ruthenium and gold. The molar absorptivities at 291 nm are equal to 5.0 × 103 and 2.2 × 104 L mol–1 cm–1 for Ru and Au, respectively, independently of the reagent used. Some methods for the determination of the content of gold (0.04%) in a cosmetic cream were developed.
☺ Biological Function of Flavonoids PDF file
Takuji Tanaka and Rikako Suzuki
First Department of Pathology, Kanazawa Medical University
1-1, Diagaku, Uchinada-machi, Kahoku-gun, Ishikawa 920-0293, Japan
Summary
The commonly accepted biological actions of flavonoids, which occur naturally in fruit, vegetables, and beverages (tea and wine), were reviewed to obtain a better understanding of the reported beneficial health effects of these substances. Data sources for this review were recent peer-reviewed scientific literature focusing on flavonoids in experiments and human health. Research in the field of flavonoids has increased since the discovery of the “French paradox”. Study reports using animal models, culture cell lines, and clinical materials were examined for content related to the role of flavonoids in human health. Key points pertaining to the function, metabolism, absorption, clinical effects, and involvement in human health were extracted and noted. Potential compromises to disease prevention are identified. Issues concerned with their potentially hazardous effects were also considered.
☺Untersuchungen zur Bioverfügbarkeit und intestinalen Absorption von Quercetin und Quercetinglykosiden PDF file
Aus dem Institut für Tierernährung und Stoffwechselphysiologie der Christian-Albrechts-Universität zu Kiel Dissertation zur Erlangung des Doktorgrades der Agrar- und Ernährungswissenschaftlichen Fakultät der Christian-Albrechts-Universität zu Kiel
vorgelegt von Sandra Landgraf Apothekerin aus Rendsburg Kiel 2003
Gedruckt mit Genehmigung der Agrar- und Ernährungswissenschaftlichen Fakultät der Christian-Albrechts-Universität zu Kiel
Dekan: Prof. Dr. F. Taube
Erster Berichterstatter: Prof. Dr. S. Wolffram
Zweiter Bericherstatter: Prof. Dr. E. Wisker
Tag der mündlichen Prüfung: 06. November 2003
Han Xu, M.D.
Pharml Medicine Technology INC.
No: A-l Fuxing Road, Haidian District, Beijing 100038, P. R. China
Subject: Warmhearted Brand Sea Buckthorn Rich Flavone Extraction Substance towards 75-Day Pre-market Notification for Dietary Supplement Substance in USA
We are Conseco Sea buckthom Co., Ltd.. Right now, we submit the documents about Yhe Warmhearted Brand Sea Buckthom Rich Flavone Extraction Substance towards 75-Day Pre-market Notification for Dietary Supplement Substance in USA” to FDA, CFSAN. Please relevant Officers review the documents according to “Federal Food, Drug, and Cosmetic Act” of USA, and tell us all of your viewpoints, in order to let us finish the whole notification process of the product.
Ö. Tokuşoğlu1,*, M. K. Ünal2, and Z. Yıldırım3
1Celal Bayar University, Akhisar M.Y.O.,45200, Akhisar, Manisa, Turkey
2Ege University, Department of Food Engineering, 35100,Bornova, İzmir, Turkey
3Ege University, Agricultural Faculty, Department of Field Crops, 35100 Bornova, Izmir, Turkey
ACTA CHROMATOGRAPHICA, NO. 13, 2003
SUMMARY The amounts of three flavonoids, quercetin, kaempferol, and myri-cetin, in tomatoes (Solanum lycopersicum L.) and tomato-based products produced in Turkey has been determined by reversed phase high-perfor-mance liquid chromatography (RPHPLC) with UV detection. The HPLC profiles of five types of tomato, one commercial composite tomato juice, and three types of tomato paste, were obtained after acid hydrolysis and extraction. The presence of the flavonol aglycons was confirmed by gas chromatography with mass spectrometric detection (GC–MS). Tomatoes and tomato-based products contained primarily quercetin, kaempferol, and the minor flavonol myricetin. The total flavonol aglycon content of different varieties of tomato varied from 3.1 to 10.0 mg kg–1 of fresh weight. Tomato juice and tomato salsa were rich in total flavonols, containing 19.8 mg L–1 and 10.5–13.2 mg kg–1, respectively. The method enabled accurate and reproducible quantitative analysis of these flavonols in tomatoes and tomato-based products.
HUNG HUYNH1, THI THANH TUYEN NGUYEN1, ELI CHAN2 and EVELYNE TRAN1
1Laboratory of Molecular Endocrinology, Division of Cellular and Molecular Research, National Cancer Centre of Singapore, Singapore 169610; 2Department of Pharmacy, National University of Singapore. Singapore 117543, Republic of Singapore
INTERNATIONAL JOURNAL OF ONCOLOGY 23: 821-829, 2003
Abstract. Because ErbB-2 receptor is involved in hormoneindependency for growth and metastasis of prostate cancer cells, the aim was to investigate the effects of quercetin on ErbB-2 and ErbB-3 expression and its critical components such as MAP kinase and PI-3 kinase. Hemocytometric counts and [3H]-thymidine incorporation were used to determine the effects of quercetin, EGF and TGF-α on cell proliferation and DNA synthesis in PC-3 and LnCap cells. Changes in ErbB-2, ErbB-3 and components of MAPK and PI-3K pathways were analyzed by Western blot analysis. Treatment of PC-3 and LnCap cells with quercetin resulted in a dose-dependent growth inhibition. The rate of DNA synthesis was decreased by 40, 55 and 65% on treatment with 14.5, 29.0 and 58.0 ìM of quercetin, respectively. Concomitantly, these treatments led to a dose-dependent decrease in ErbB-2, ErbB-3 and their basal autophosphorylation levels as compared to controls. Cyclin D1 expression and basal phosphorylation of c-Raf, MAPK, Elk-1 and Akt-1 in PC-3 cells was also inhibited by quercetin treatment. Co-treating PC-3 cells with quercetin significantly attenuated EGF- and TGF-α-induced growth and phosphorylation of ErbB-2, ErbB-3, c-Raf, MAPK kinase 1/2 (MEK1/2), MAPK, Elk-1 and Akt-1. Since ErbB receptor is important for growth, metastasis and drug resistance, inhibition of ErbB-2 and ErbB-3 by pharmacological doses of quercetin may provide a new approach for treatment of prostate cancers.
Key words: ErbB-2 and ErbB-3 expression, quercetin, proliferation,EGF, TGF-α
☺ Evaluation of the Antioxidant Activity of Different Flavonoids by the Chemiluminescence Method PDF file
Sandra R. Georgetti,1 Rúbia Casagrande,1 Valéria M. Di Mambro,1 Ana ECS. Azzolini,2 and Maria JV. Fonseca1
1Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Av do Café s/n, 14040-903, Ribeirão Preto, Brazil 2Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto - USP, Av do Café s/n, 14040-903, Ribeirão Preto, Brazil
AAPS PharmSci 2003; 5 (2) Article 20 (http://www.pharmsci.org).
The objective of the present investigation was to study the antioxidant action of different flavonoids (quercetin, glabridin, red clover, and Isoflavin Beta, an isoflavones mixture) in order to determine if they could be added to a topical formulation used to treat damage caused by free radicals. Samples of 10 µL of the test compounds at different concentrations were mixed with 0.1 M phos-phate buffer, pH 7.4, and a luminol solution was added to yield a final concentration of 0.113 mM. Hydrogen peroxide was then added at a final concentration of 0.05 mM. The reaction was started by introducing the horse-radish peroxidase enzyme at a final concentration of 0.2 IU/mL, in a final volume of 1.0 mL. Chemilumines-cence was measured for 10 minutes at room tempera-ture, and dimethylsulfoxide (DMSO) was used as a con-trol. All samples showed marked inhibition of oxidative stress, with a concentration-dependent action for quercetin and Isoflavin Beta. The highest inhibition was observed with glabridin and the dry red clover extract. All flavonoids proved to be adequate for addition to topical formulations because of their high antioxidant activity.
KEYWORDS: chemiluminescence, luminol, antioxi-dants, flavonoids, peroxidase
☺ Naturally occurring 2’-hydroxyl-substituted flavonoids as high-affinity benzodiazepine site ligands PDF file
Michael S.Y. Huena, Kwok-Min Huia, Justin W.C. Leunga, Erwin Sigelb, Roland Baurb, J. Tze-Fei Wonga, Hong Xuea,*
aDepartment of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
bPharmacological Institute, University of Bern, Friedbuehlstr 49, CH-3010, Bern, Switzerland
Biochemical Pharmacology 66 (2003) 2397–2407
Abstract: Screening of traditional medicines has proven invaluable to drug development and discovery. Utilizing activity-guided purification, we previously reported the isolation of a list of flavonoids from the medicinal herb Scutellaria baicalensis Georgi, one of which manifested an affinity for the benzodiazepine receptor (BDZR) comparable to that of the synthetic anxiolytic diazepam (Ki 6:4 nM). In the present study, this high-affinity, naturally occurring flavonoid derivative, 5,7,20-trihydroxy-6,8-dimethoxyflavone (K36), was chosen for further functional and behavioral characterization. K36 inhibited [3H]flunitrazepam binding to native BDZR with a Ki value of 6.05 nM. In electrophysiological experiments K36 potentiated currents mediated by rat recombinant a1b2g2 GABAA receptors expressed in Xenopus oocytes. This potentiation was characterized by a threshold (1 nM) and half-maximal stimulation (24 nM) similar to diazepam. This enhancement was demonstrated to act via the BDZR, since co-application of 1 mM of the BDZR antagonist Ro15-1788 reversed the potentiation. Oral administration of K36 produced significant BDZR-mediated anxiolysis in the mice elevated plus-maze, which was abolished upon co-administration of Ro15-1788. Sedation, myorelaxation and motor incoordination were not observed in the chosen dosage regimen. Structure–activity relationships utilizing synthetic flavonoids with different 20 substituents on the flavone backbone supported that 20-hydroxyl-substitution is a critical moiety on flavonoids with regard to BDZR affinities. These results further underlined the potential of flavonoids as therapeutics for the treatment of BDZR-associated syndromes.
Keywords: Benzodiazepines; Benzodiazepine receptor; Flavonoids; Structure–activity relationship; Scutellaria baicalensis Georgi; Anxiolytics
☺Modified Flavonoids as strong photoprotecting UV-Absorbers and Antioxidants PDF file
H.-D. Martin1, S. Beutner1, S. Frixel1, B. Bloedorn1, I. Hernández Blanco1, B. Mayer1, A. Pérez Gálvez1, C. Ruck1, M. Schmidt1, S. Sell1, T. Hoffmann1, P. Noack1, I. Schuelke1, N. Kiesendahl1, R. Scherrers1, H. Sies2, W. Stahl2, H. Ernst3, S. Haremza3 and R. Walsh4
1University of Duesseldorf, Department of Chemistry, Universitaetsstr. 1, D-40225 Duesseldorf, Germany. 2University of Duesseldorf, Department of Physiological Chemistry, Universitaetsstr. 1, D-40225 Duesseldorf, Germany. 3BASF AG, D-67056 Ludwigshafen, Germany. 4University of Reading, Department of Chemistry, Reading, UK
Keywords: Flavonoids; UV-Absorber; Multichromophoric Systems; Antioxidants; Bridged Chromophores
SUMMARY: The synthesis, spectroscopy and photochemical stabilities of novel modified flavonoids and chro-mone derivatives are described. These compounds act as photoprotecting UV-absorbers as well as antioxidants. The investigation of structure-activity as well as structure-stability relationships is a primary aim of this work. Furthermore the synthetic work tries to improve the essential properties of the protecting systems by combining different active building blocks to an even better multi-chromophoric system.
☺Structure-Radical Scavenging Activity Relationships of Flavonoids PDF file
Dragan Ami},a,* Du{anka Davidovi}-Ami},a Drago Be{lo,a and Nenad Trinajsti}b
aFaculty of Agriculture, The Josip Juraj Strossmayer University, P.O. Box 719, HR-31107 Osijek, Croatia
bThe Rugjer Bo{kovi} Institute, P.O. Box 180, HR-10002 Zagreb, Croatia
CROATICA CHEMICA ACTA CCACAA 76 (1) 55¿61 (2003)
The relationship between the structural characteristics of 29 flavonoids and their antiradical activity was studied. The obtained results suggest that the free radical scavenger potential of these polyphenolic compounds closely depends on the particular substitution pattern of free hydroxyl groups on the flavonoid skeleton. The possible mechanism of action of flavonoids lacking B ring OHs as free radical scavengers has been proposed.
Key words：flavonoids; free radical scavenging activity; structure-activity relationships
☺Intracellular metabolism and bioactivity of quercetin and its in vivo metabolites PDF file
Jeremy P. E. SPENCER, Gunter G. C. KUHNLE, Robert J. WILLIAMS and Catherine RICE-EVANS1
Wolfson Centre for Age-Related Diseases, GKT School of Biomedical Sciences, Hodgkin Building, King’s College, Guy’s Campus, London SE1 9RT, U.K.
Biochem. J. (2003) 372, 173–181
Understanding the cellular effects of flavonoid metabolites is important for predicting which dietary flavonoids might be most beneficial in vivo. Here we investigate the bioactivity in dermal fibroblasts of the major reported in vivo metabolites of quercetin, i.e. 3_-O-methyl quercetin, 4_-O-methyl quercetin and quercetin 7-O-β-D-glucuronide, relative to that of quercetin, in terms of their further metabolism and their resulting cytotoxic and/or cytoprotective effects in the absence and presence of oxidative stress. Uptake experiments indicate that exposure to quercetin led to the generation of two novel cellular metabolites, one characterized as a 2_-glutathionyl quercetin conjugate and another product with similar spectral characteristics but 1mass unit lower, putatively a quinone/quinone methide. A similar product was identified in cells exposed to 3_-O-methyl quercetin, but not in the lysates of those exposed to its 4_-O-methyl counterpart, suggesting that its formation is related to oxidative metabolism. There was no uptake or metabolism of quercetin 7-O-β-D-glucuronide by fibroblasts. Formation of oxidative metabolites may explain the observed concentration-dependent toxicity of quercetin and 3_-O-methyl quercetin, whereas the formation of a 2_-glutathionyl quercetin conjugate is interpreted as a detoxification step. Both O-methylatedmetabolites conferred less protection than quercetin against peroxide-induced damage, and quercetin glucuronide was ineffective. The ability to modulate cellular toxicity paralleled the ability of the compounds to decrease the level of peroxideinduced caspase-3 activation. Our data suggest that the actions of quercetin and its metabolites in vivo are mediated by intracellular metabolites.
Keywords: fibroblast, flavonoid, glucuronide,MS,O-methylated, oxidative stress.
☺Quercetin regulates growth of Ishikawa cells through the suppression of EGF and cyclin D1 PDF file
MASANORI KANEUCHI1,2, MASAHIRO SASAKI1,2, YUICHIRO TANAKA1, NORIAKI SAKURAGI2, SEIICHIRO FUJIMOTO2 and RAJVIR DAHIYA1
1Department of Urology, University of California, and Veterans Affairs Medical Center, San Francisco, CA 94121, USA;
2Department of Obstetrics and Gynecology, Hokkaido University School of Medicine, Sapporo, Japan INTERNATIONAL JOURNAL OF ONCOLOGY 22: 159-164, 2003
Abstract.: Quercetin and other polyphenols have anticarcinogenic and anti-tumorigenic activity in various organs, however, studies of this activity are lacking in endometrial cancer. We hypothesize that quercetin has anti-proliferative activity and the mechanisms of quercetin action may be through modulation of cell cycle and cell growth regulatory genes. To test this hypothesis, we treated endometrial cancer cells (Ishikawa cell line) with quercetin, and cell proliferation, expression of growth signal genes (EGF, VEGF, and TGF-α), cell cycle genes (p53, p21, p73, and cyclin D1), and apoptosisrelated genes (bcl-2 and bax) were analyzed. Results of these experiments demonstrate that after a 7-day exposure to 1, 10 and 100 μM of quercetin, growth of Ishikawa cells was inhibited by 3, 51 and 87%, respectively. The gene and protein expression data suggest that quercetin treatment (100 μM) significantly decreased EGF and cyclin D1, whereas VEGF was up-regulated in Ishiwaka cell lines. Other genes such as TGF-α, p53, p21, p73, bcl-2 and bax were not significantly changed with quercetin treatment in Ishiwaka cell lines. The present study suggests that quercetin can suppress proliferation of Ishikawa cells through down-regulation of EGF and cyclin D1.
☺ Effect of Quercetin on Daunorubicin-Induced Heart Mitochondria Changes in Rats PDF file
J. GUZY, J. KU.NÍR, M. MAREKOVÁ, Z. CHAVKOVÁ, K. DUBAYOVÁ, G. MOJ.I.OVÁ1, L. MIROSSAY2, J. MOJ.I.2
Department of Medical Chemistry and Biochemistry, 1Department of Experimental Medicine and
2Department of Pharmacology, Medical Faculty, Šafarik University, Košice, Slovak Republic
Summary: Cancer therapy with daunorubicin is limited by its cardiotoxicity. It has been suggested that daunorubicin-induced free radical generation can be involved. The precise molecular mechanism of daunorubicin-induced cardiotoxicity is still not well understood but it is believed that mitochondria play an important role in this process. It has been reported that flavonoids with antioxidant properties may prevent anthracycline-induced cardiotoxicity. In this work, we investigated the effects of daunorubicin and quercetin on mitochondrial enzyme activities such as ATPase, glutathione peroxidase (GPx) and glutathione reductase (GR). Moreover, we also studied the changes of outer mitochondrial membrane using synchronous fluorescence spectra. The actitivity of ATPase and GR were significantly increased after daunorubicin application. Pretreatment with quercetin significantly alleviated this increase. On the other hand, GPx activity was significantly decreased and quercetin prevented this decrease. Treatment with quercetin alone had no significant effect on the enzyme activity studied. Quercetin also completely prevented daunorubicin-induced changes in fluorescence of the outer mitochondrial membrane. In conclusion, our data indicate that quercetin may be useful in mitigating daunorubicin-induced cardiotoxicity.
Key words: Mitochondria; Antioxidant enzymes; Daunorubicin; Quercetin; Synchronous fluorescence spectra
Superfund Basic Research Program Annual Meeting Dartmouth College November 9-12, 2003
Pachaikani Ramadass,1 Purushothaman Meerarani, 1 Michal Toborek,2 Larry W. Robertson,3 and Bernhard Hennig,1 (presented by Viswanathan Saraswathi1)
1Molecular and Cell Nutrition Laboratory, College of Agriculture, and 2Department of Surgery, University of Kentucky, Lexington, KY 40546, and 3Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, IA 52242
Polychlorinated biphenyls (PCBs), especially the more coplanar PCBs, have been shown to induce oxidative stress, various transcription factors and subsequent inflammatory processes critical to atherosclerosis in vascular endothelial cells. Dietary flavonoids like catechins and quercetin possess anti-oxidant and anti-inflammatory properties. To test the hypothesis that flavonoids can modify PCB-mediated endothelial cytotoxicity, endothelial cells were treated with epigallocatechin-3-gallate (EGCG; 5 to 50 µM) or quercetin (10 to 100 µM) with or without PCB 77 (3,3’,4,4’- tetrachlorobiphenyl, 3.4 µM) for 6 h. EGCG and quercetin strongly and in a concentration-dependent manner inhibited oxidative stress induced by PCB 77 as measured by DCF fluorescence. The role of cytochrome P450 1A1 (CYP1A1) in the PCB-induced toxicity was investigated. EGCG at 50 µM and quercetin at 100 µM concentrations markedly inhibited CYP1A1 mRNA levels and enzyme activity. Furthermore, EGCG or quercetin down-regulated the PCB 77-mediated increase in AhR DNA binding activity. These data suggest that protective effects of EGCG and quercetin are initiated upstream from CYP1A1 and that these flavonoids may be of value for inhibiting the toxic effects of PCBs in vascular endothelial cells (Supported by grants from NIEHS/NIH (P42 ES 07380) and the KY Agr. Exp. Satation).
Gordana Rusak3*, Herwig O. Gutzeit1 and Jutta Ludwig-Müller2
1Institute of Zoology, TU Dresden, D-01062 Dresden, Germany
2Institute of Botany, TU Dresden, D-01062 Dresden, Germany
3Department of Biology, Faculty of Science, Maruli}ev trg 20/II, 10000 Zagreb, Croatia
Food Technol. Biotechnol. 40 (4) 267–273 (2002)
Summary: Quercetin is a known specific inhibitor of hsp70 synthesis and thus might be a potent agent for enhancing the selective cytotoxicity of heat on tumour cells. A comparative analysis of the effects of quercetin and five structurally related flavonoids on hsp90_ , hsp70A, hsp60 and hsp27 gene expression was carried out using human myeloid leukaemia cells (HL-60). The cells were preincubated with 50 _ M quercetin, kaempferol, myricetin, taxifolin, isorhamnetin, methylquercetagetin or 0.1 % DMSO (controls) for 24 h at 37°C before heat shock treatment (43 °C for 30 min). Total RNA was isolated from heat-stressed and unstressed cells and analysed by RT-PCR. Hsp27 gene expression was inhibited by flavonoids more strongly than other hsp genes investigated in heat stressed as well as in unstressed cells. Among the hsp genes tested, only hsp60 was expressed above control level under the influence of taxifolin. Members of the hsp70 and hsp27 families are highly expressed in breast and lung cancer and leukaemias and they play a role in the acquired resistance to chemotherapy or radiation therapy combined with hyperthermia. Therefore, hsps present potential targets for cancer diagnosis and treatment. The present structure/activity study indicates that position, number and substitution of hydroxyl groups of the B ring and saturation of the C2-C3 bond are important factors affecting flavonoid activity on hsp gene expression. This study could help provide a basis for further design of specific inhibitors of hsp gene expression.
Key words: hsp genes, flavonoids, leukaemia, HL-60, dietary supplements
☺ The study of flavonoids and glycosides in the Digitalis lanata PDF file
K Pozsonyi University of Pécs, Faculty of Sciences, Department of Botany, Pécs, Hungary
Volume 46(3-4):253-254, 2002 Acta Biologica Szegediensis
ABSTRACT : The population of Digitalis lanata was studied in hillocks of Pécs-Nagyárpád, the southern part of Transdanubia in Hungary. The qualitative analysis of digitalis-glycosides and flavonoids in the leaves of naturally growing Digitalis lanata was carried out. The qualitative analysis was carried out by TLC. The digitalis-glycoside content was smaller in the leaves of naturally growing Digitalis lanata than in the leaves of cultivated variations.
KEY WORDS : Digitalis lanata digitalis-glycosides flavonoids TLC
O. Korbut1, M. Bučková2,*, J. Labuda2 and P. Gründler1
1 Department of Chemistry, Rostock University, 18051 Rostock, Germany
2 Department of Analytical Chemistry, Slovak University of Technology, 81237 Bratislava, Slovak Republic
Sensors 2003, 3, 1–10
Abstract: A simple electrochemical sensor consisting of electrically heated carbon paste electrode with the surface modified by dsDNA is used to characterize voltammetric behaviour and antioxidative activity of four selected flavonoids. Quercetin, rutin, catechin and epigallocatechin gallate accumulate within the DNA layer. A positive effect of the electrode temperature within the range of 20 to 38 ºC on the detection of a deep DNA degradation by a copper(II)/H2O2/ascorbic acid cleavage mixture as well as an antioxidative effect of flavonoids was evaluated.
Keywords: Flavonoids, Antioxidants, DNA biosensor, Carbon paste electrode, Heated electrode
Z Juzyszyn,a B Czerny, Z Myśliwiec, A Put Szczecin, Poland
Fluoride Vol. 35 No. 3 161-167 2002 Research Report
Summary: The respiratory activity of liver and kidney slices of rats chronically exposed to ammonium fluoride was studied. It was found that a mixture of quercetin sulfonates stimulated tissue metabolism and exerted a protective effect in NH4F intoxication through normalization of respiratory activity.
Keywords: Ammonium fluoride, Fluoride in rats, Kidney respiration, Liver respiration, Quercetin sulfonates.
B Czerny,a A Put, Z Myśliwiec, Z Juzyszyn Szczecin, Poland
Fluoride Vol. 33 No. 1 27-32 2000 Research Report
SUMMARY: Male Wistar rats were exposed to ammonium fluoride vapours in a toxicological chamber for 3 months. A mixture of sulfonic acid sodium salts of quercetin at a dose of 5 or 20 mg/kg body weight/24 h was given to some of the animals. It was found that quercetin salts alleviate changes in hepatic metabolism of lipids caused by ammonium fluoride.
Keywords: Ammonium fluoride, Fluoride toxicity, Fluoride vapours, Lipid metabolism, Quercetin.
Alenka [tefani~-Petek,a Ale{ Krbav~i~,b and Tom [olmajerc,**
a Faculty of Chemistry and Chemical Technology, University of Ljubljana, A{kerceva 5, 1000 Ljubljana, Slovenia
b Faculty of Pharmacy, University of Ljubljana, A{kerceva 7,1000 Ljubljana, Slovenia
c Department of Molecular Modeling and NMR Spectroscopy, National Institute of Chemistry and Lek, d.d., P. O. Box 660, 1001 Ljubljana, Slovenia
CROATICA CHEMICA ACTA CCACAA 75 (2) 517529 (2002)
Flavonoids are a group of low molecular weight plant products, based on the parent compound, flavone (2-phenylchromone) and have shown potential for application in a variety of pharmacological targets. By using random screening techniques flavones have been proposed as inhibitors of aldose reductase, an enzyme crucial in the treatment of diabetic complications such as cataract formation. On the other hand, a large number of natural and synthetic flavonoids are being tested as specific inhibitors of protein tyrosine kinase (PTK). Kinetic analyses of the PTK inhibition indicate that flavonoids are competitive inhibitors with respect to the nucleotide ATP. A thorough investigation of the available experimental data base by using both classical and quantum chemical descriptors has been performed in order to develop quantitative structure-activity relationships for these enzyme systems. Relevance of the descriptors to binding properties of both enzyme receptors active site is proposed and the obtained results demonstrate in detail which specific electronic as well as the hydrophobic and steric properties of the substituents play a significant role in their differential binding.
Key words: QSAR, flavonoid derivatives, aldose reductase, protein tyrosine kinase.
Hisashi MATSUDA, Toshio MORIKAWA, Iwao TOGUCHIDA, and Masayuki YOSHIKAWA*
Kyoto Pharmaceutical University; Misasagi, Yamashina-ku, Kyoto 607–8412, Japan.
Received January 15, 2002; accepted February 13, 2002
The methanolic extracts of several natural medicines and medicinal foodstuffs were found to show an inhibitory effect on rat lens aldose reductase. In most cases, flavonoids were isolated as the active constituents by bioassay-guided separation, and among them, quercitrin (IC5050.15 μM), guaijaverin (0.18 μM), and desmanthin-1 (0.082 μM) exhibited potent inhibitory activity. Desmanthin-1 showed the most potent activity, which was equivalent to that of a commercial synthetic aldose reductase inhibitor, epalrestat (0.072 μM). In order to clarify the structural requirements of flavonoids for aldose reductase inhibitory activity, various flavonoids and related compounds were examined. The results suggested the following structural requirements of flavonoid: 1) the flavones and flavonols having the 7-hydroxyl and/or catechol moiety at the B ring (the 39,49-dihydroxyl moiety) exhibit the strong activity; 2) the 5-hydroxyl moiety does not affect the activity; 3) the 3-hydroxyl and 7-O-glucosyl moieties reduce the activity; 4) the 2–3 double bond enhances the activity; 5) the flavones and flavonols having the catechol moiety at the B ring exhibit stronger activity than those having the pyrogallol moiety (the 39,49,59-trihydroxy moiety).
Key words aldose reductase inhibitor; flavonoid; structural requirement; desmanthin-1; quercitrin; guaijaverin
☺ Flavonoids Suppress the Cytotoxicity of Linoleic Acid Hydroperoxide toward PC12 Cells -PDF file
Naoko SASAKI,a Takeshi TODA,a Takao KANEKO,b Naomichi BABA,c and Mitsuyoshi MATSUO*,a
a Department of Biology, Faculty of Science and High Technology Research Center, Konan University; 8–9–1 Okamoto, Higashinada-ku, Kobe 658–8501, Japan: b Tokyo Metropolitan Institute of Gerontology; 35–2 Sakaecho, Itabashi-ku, Tokyo 173–0015, Japan: and c Department of Bioresources Chemistry, Faculty of Agriculture, Okayama University; 1–1–1 Tsushimanaka, Okayama 700–8530, Japan. Received March 18, 2002; accepted April 30, 2002
The suppressive effect of flavonoids on the cytotoxicity of linoleic acid hydroperoxide (LOOH) toward rat phenochromocytoma PC12 cells was examined. The extent of cytotoxicity was shown on the basis of % survival determined by the trypan blue exclusion test. On preincubation of cells with either 3-hydroxyflavone, quercetin, or luteolin prior to LOOH exposure, the cytotoxicity was considerably suppressed. In contrast, on coincubation of cells with either eriodictyol, quercetin, kaempherol, luteolin, or 3-hydroxyflavone and LOOH, it was markedly suppressed. Regardless of incubation conditions, quercetin, 3-hydroxyflavone, and luteolin were thus more effective as protective agents against the cytotoxicity than the other flavonoids. These flavonoids further showed a suppressive effect on coincubation rather than on preincubation. These results suggest that such flavonoids are bene-ficial for cells under oxidative stress.
Key words flavonoid; linoleic acid hydroperoxide; PC12 cell; cytotoxicity; antioxidant activity
☺ Flavonoids in Cell Function -PDF file
edited by Béla Buslig , State of Florida Department of Citrus, Lake Alfred, USA and John Manthey, USDA Citrus and Subtropical Products Lab. Winter Haven, FL, USA
ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 505
April 2002 Hardbound 208 pp. ISBN 0-306-47254-6
This volume is based on presentations made the symposium Flavonoids in Cell Function, held during the 219th National Meeting of the American Chemical Society in San Francisco, California on March 29-30, 2000. The papers cover a range of topics discussing various approaches to flavonoid study, starting at plant-microbe communication through analytical methods to medicinal and systemic ramificaitons of these compounds.
Arkadiusz Orzechowski(1), Katarzyna Grzelkowska, Wojciech Karlik and Tomasz Motyl
(1) Department of Physiology, Biochemistry, Pharmacology and Toxicology, Faculty of Veterinary Medicine, Warsaw Agricultural University, Warsaw, Poland
Basic Appl Myol 11 (1): 31-44, 2001
Abstract: Conflicting data regarding the effect of antioxidants on skeletal myogenesis prompted us to study the action of superoxide anion and hydroxyl radical scavengers on differentiating murine C2C12 myoblasts. The onset of myotube formation was delayed by quercetin and DMSO while DNA synthesis was stimulated in response to elevated doses of both factors. Cell viability measured by MTT assay was inhibited either by 100 μM quercetin or 1% or 2% of DMSO whereas elevated number of apoptotic cells was detected at the same time. Muscle cell differentiation retarded by quercetin or DMSO was reflected by delay in myogenin expression and lowered distribution of myotubes with low (< 10) number of cell myonuclei. For large myotubes (> 10) low scores for DMSO, and high scores for quercetin were observed. Based on phosphorylation status, both antioxidants delayed PKB activation and PKB-dependent differentiation, as well as antiapoptotic effect of PKB. Bcl-2 antiapoptotic protein level was elevated earlier for control than for experimental treatment. Muscle creatine kinase activity reflected the reduced rate of myogenesis. In conclusion, promitogenic activity of quercetin and DMSO disturbs differentiation programme of myoblasts and might explain why more apoptotic cells was found after high doses of both factors. In contrast to DMSO, quercetin-induced delay in myogenesis may result in larger muscle mass. Results of this study support the idea that muscle differentiation can be regulated by scavengers of superoxide anion and hydroxyl radical.
Key words: antioxidants, apoptosis, Bcl-2, muscle differentiation, myogenin, PKB.
☺ Flavonoids Act as Negative Regulators of Auxin Transport in Vivo in Arabidopsis1 -PDF file
Dana E. Brown, Aaron M. Rashotte, Angus S. Murphy2, Jennifer Normanly, Brian W. Tague, Wendy A. Peer2, Lincoln Taiz, and Gloria K. Muday*
Department of Biology, Wake Forest University, Winston-Salem, North Carolina 27109 (D.E.B., A.M.R., B.W.T., G.K.M.); Biology Department, University of California, Santa Cruz, California 95064 (A.S.M., W.A.P., L.T.); and Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003 (J.N.)
Plant Physiology, June 2001, Vol. 126, pp. 524–535,
Polar transport of the plant hormone auxin controls many aspects of plant growth and development. A number of synthetic compounds have been shown to block the process of auxin transport by inhibition of the auxin efflux carrier complex. These synthetic auxin transport inhibitors may act by mimicking endogenous molecules. Flavonoids, a class of secondary plant metabolic compounds, have been suggested to be auxin transport inhibitors based on their in vitro activity. The hypothesis that flavonoids regulate auxin transport in vivo was tested in Arabidopsis by comparing wild-type (WT) and transparent testa (tt4) plants with a mutation in the gene encoding the first enzyme in flavonoid biosynthesis, chalcone synthase. In a comparison between tt4 and WT plants, phenotypic differences were observed, including three times as many secondary inflorescence stems, reduced plant height, decreased stem diameter, and increased secondary root development. Growth of WT Arabidopsis plants on naringenin, a biosynthetic precursor to those flavonoids with auxin transport inhibitor activity in vitro, leads to a reduction in root growth and gravitropism, similar to the effects of synthetic auxin transport inhibitors. Analyses of auxin transport in the inflorescence and hypocotyl of independent tt4 alleles indicate that auxin transport is elevated in plants with a tt4 mutation. In hypocotyls of tt4, this elevated transport is reversed when flavonoids are synthesized by growth of plants on the flavonoid precursor, naringenin. These results are consistent with a role for flavonoids as endogenous regulators of auxin transport.
Chul-Ho Lee,*,1 Tae-Sook Jeong,†,1 Yang-Kyu Choi,* Byung-Hwa Hyun,*,‡ Goo-Taeg Oh,* Eun-Hee Kim,* Ju-Ryoung Kim,† Jang-Il Han,† and Song-Hae Bok†,‡,2
*Genetic Resources Center and †Cardiovascular Research Laboratory, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Yusong P.O. Box 115, Taejon 305-600, Korea; and ‡BioNutrigen Company, Ltd., #52 Eoun, Yusong, Taejon 305-333, Korea
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Vol. 284, No. 3, 2001
The anti-atherogenic effects of the citrus flavonoids, naringin and naringenin, were evaluated in high cholesterol-fed rabbits. At 3 months of age, 30 male New Zealand White (NZW) rabbits were divided into three groups (n=10 per group). The rabbits were fed a 1% cholesterol diet alone (control group) or a diet supplemented with either 0.1% naringin or 0.05% naringenin for 8 weeks. The plasma lipoprotein levels, total cholesterol, triglyceride, and high-density lipoprotein showed no significant differences in the control and experimental groups. Hepatic acyl-CoA: cholesterol acyltransferase (ACAT) activity was slightly low in naringin (5.0%)- and naringenin (15.0%)- fed rabbits, compared to control group. The aortic fatty streak areas were significantly lower in both the naringin (19.2±5.6%)- and naringenin (18.1±6.5%)-supplemented groups than in the control group (60.4±14.0%). The expression levels of vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemotactic protein- 1 (MCP-1), by semiquantitative RT-PCR analysis of the thoracic aorta, were significantly lower in the flavonoids supplemented groups than in the control group. These results suggest that the anti-atherogenic effect of the citrus flavonoids, naringin and naringenin, is involved with a decreased hepatic ACAT activity and with the downregulation of VCAM-1 and MCP-1 gene expression.
Key Words: naringin; naringenin; fatty streak; ACAT; MCP-1; VCAM-1.
Hagen SCHROETER*., Jeremy P. E. SPENCER., Catherine RICE-EVANS. and Robert J. WILLIAMS*1
*Centre for Neuroscience Research, Guy's, King's and St. Thomas ' School of Biomedical Sciences, Hodgkin Building, Guy's Campus, London SE1 1UL, U.K., and .Wolfson Centre for Age Related Diseases, Guy's, King's and St. Thomas ' School of Biomedical Sciences, Guy's Campus, London SE1 1UL, U.K.
Biochem. J. (2001) 358, 547±557
Oxidative stress has been associated with neuronal loss in neurodegenerative diseases and during age-associated cognitive decline. Flavonoids have been proposed to play a useful role in protecting the central nervous system against oxidative and excitotoxic stress, although the mechanism of action is unknown. Using oxidized low-density lipoprotein (oxLDL) as the oxidative insult we investigated the mechanism of neurotoxicity and attempted to identify possible sites of action of two of the most potent protective ¯avonoids, epicatechin and kaempferol, in cultured primary neurons. Using cultured striatal neurons and selective phosphospeci®c antibodies we addressed the potential role of extracellular signal-regulated kinases 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK). OxLDL stimulated a Ca2+- dependent activation of bothERK1}2 and JNKthat was strongly inhibited by pre-treatment with low micromolar concentrations of epicatechin. Neurotoxicity induced by oxLDL, however, was neither reduced nor enhanced by inhibiting ERK1/2 activation with mitogen-activated protein kinase kinase (MEK) inhibitors, suggesting that this cascade is unlikely to be involved in either oxLDL toxicity or the protective effects of ¯avonoids. oxLDL caused a sustained activation of JNK that resulted in the phosphorylation of the transcription factor c-Jun, which was abolished in neurons pre-treated with ¯avonoids. Furthermore, oxLDL induced the cleavage of procaspase-3 and increased caspase-3-like protease activity in neurons, an effect which was strongly inhibited by pre-exposure to either epicatechin or kaempferol. In addition, a caspase-3 inhibitor reduced oxLDLinduced neuronal death, implicating an apoptotic mechanism. A major in .i.o metabolite of epicatechin, 3«-O-methyl-epicatechin was as effective as epicatechin in protecting neurons. Thus dietary ¯avonoids might have potential as protective agents against neuronal apoptosis through selective actions within stress-activated cellular responses, including protein kinase signaling cascades.
Key words: epicatechin, ERK, MAP kinase, oxidative stress, striatal neuron.
1Department of Pharmaceutical Biochemistry, 2Department of Immunodiagnostics, and 3Department of Pharmaceutical Botany, Karol Marcinkowski University of Medical Sciences, Poznañ, Poland
Acta Biochimica Polonica Vol. 48 No. 1/2001 183–189
Two natural flavonoids, quercetin and isorhamnetin 3-O-acylglucosides, were examined for their inhibitory influence on the in vitro production and release of reactive oxygen species in polymorphonuclear neutrophils (PMNs). The generation of superoxide radical, hydrogen peroxide and hypochlorous acid were measured by, respectively, cytochrome c reduction, dichlorofluorescin oxidation and taurine chlorination. Membrane lipid oxidation was studied by the thiobarbituric acid method in mouse spleen microsomes. The addition of flavonoids at the concentration range 1–100 _M inhibited PMNs oxidative metabolism and lipid peroxidation in a dose-dependent manner. The results suggest that these flavonoids suppress the oxidative burst of PMNs and protect membranes against lipid peroxidation.
Key words: flavonoids, respiratory burst, reactive oxygen species, flow cytometry, lipid peroxidation, polymorphonuclear neutrophils
☺ Quercetin, E7 and p53 in papillomavirus oncogenic cell transformation -PDF file
Carcinogenesis vol.22 no.7 pp.1069–1076, 2001
R.G.Beniston, I.M.Morgan, V.O’Brien1 and M.S.Campo2
Ping-Chuen Ho, Dorothy J. Saville
School of Pharmacy, University of Otago, Dunedin, New Zealand Sompon Wanwimolruk
College of Pharmacy, Western University of Health Sciences, Pomona, California, USA
Received March 30, 2001, Revised August 23, 2001, Accepted August 24, 2001
PURPOSE:. To evaluate the inhibition of CYP3A4 activity in human liver microsomes by flavonoids, furanocoumarins and related compounds and investigate possibly more important and potential inhibitors of CYP3A4 in grapefruit juice. METHODS: The effects of various flavonoids and furanocoumarin derivatives on CYP3A4 activity in two human liver microsomal samples was determined using quinine as a substrate. All flavonoids and furanocoumarin derivatives were dissolved in DMSO. In all cases, inhibition activities were compared with activities in control incubations containing 0.2% (v/v) DMSO. RESULTS: The results showed that the inhibition of quinine 3-hydroxylation (CYP3A4 activity) by bergapten (67%), and quercetin (55%) was greater than naringenin (39%) and naringin (6%), at the same inhibitor concentration of 100 µM. The results also demonstrated that the furan ring in the furanocoumarins enhanced the inhibitory effect on CYP3A4 activity. Flavonoids with more phenolic hydroxyl (-OH) groups produced stronger inhibition than those with less hydroxyl groups. Of all the chemicals studied, bergapten (5-methoxypsoralen) with the lowest IC50 value (19-36 ìM) was the most potent CYP3A4 inhibitor. CONCLUSIONS: These results suggest that more than one component present in grapefruit juice may contribute to the inhibitory effect on CYP3A4. Bergapten appears to be a potent inhibitor of CYP3A4, and may therefore be primarily responsible for the effect of grapefruit juice on CYP3A4 activity.
☺Enhanced Antioxidant Activity After Chlorination of Quercetin by Hypochlorous Acid -PDF file
Ralf Binsack, Brenda J. Boersma, Rakesh P. Patel, Marion Kirk, C. Roger White, Victor Darley-Usmar, Stephen Barnes, Fen Zhou, and Dale A. Parks
Vol. 25, No. 3 March 2001 ALCOHOLISM: CLINICAL AND EXPERIMENTAL RESEARCH
Background: Several epidemiological studies indicate that moderate consumption of red wine decreases both the incidence and mortality associated with cardiovascular disease. Quercetin and rutin (quercetin-3-rutinoside) are polyphenols present in relatively large concentrations in red wine and may play a role in this cardioprotective phenomenon. The precise mechanisms of cardioprotection remain unclear but may involve the action of these polyphenols as antioxidants, which attenuate the tissue injury that results from the production of proinflammatory oxidants such as hypochlorous acid (HOCl). Methods: To study the interaction of these polyphenols with proinflammatory oxidants, we mixed quercetin or rutin with HOCl (0–150 mM) and analyzed the reaction products by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance. Results: Stable mono- and dichlorinated derivates were detected for both quercetin and the glycoside derivative, rutin, which suggests that both the conjugated and unconjugated forms of quercetin reacted with HOCl similarly. Chlorination of quercetin occurred only at two sites, and the derivates (6-chloroquercetin, 6,8-dichloroquercetin) were more potent antioxidants toward oxidative modification of low-density lipoproteins and ABTS radical formation than the unmodified form. Conclusions: These data suggest that under certain pathological conditions in vivo (e.g., inflammation), flavonols may be converted to chlorinated derivates, which exhibit an enhanced antioxidant potential and thereby play a role in cardioprotection.
Key Words: Quercetin, Rutin, Hypochlorous Acid, Chlorination, High-Performance Liquid Chromatography, Mass Spectrometry, Nuclear Magnetic Resonance.
K. RAJ NARAYANA, M. SRIPAL REDDY, M.R. CHALUVADI, D.R. KRISHNA*
Drug Metabolism & Clin. Pharmacokinetics Division, University College of Pharmaceutical Sciences, Kakatiya University, Warangal-506 009.
Indian Journal of Pharmacology 2001; 33: 2-16
Flavonoids belong to a group of polyphenolic compounds, which are classified as flavonols, flavonones, flavones, flavanols, flavan-3-ols and isoflavones according to the positions of the substitutes present on the parent molecule. Flavonoids of different classes have several pharmacological activities. Flavonoids have also been known to posses biochemical effects, which inhibit a number of enzymes such as aldose reductase, xanthine oxidase, phosphodiesterase, Ca+2-ATPase, lipoxygenase, cycloxygenase, etc. They also have a regulatory role on different hormones like estrogens, androgens and thyroid hormone. In view of their wide pharmacological and biological actions, they seem to be having a great therapeutic potential.
Flavonoids; biochemistry; pharmacology; therapeutic; potential
☺ ANTI-INFLAMMATORY ACTIONS OF FLAVONOIDS AND STRUCTURAL REQUIREMENTS FOR NEW DESIGN -PDF file
T.C. THEOHARIDES 1,2, M. ALEXANDRAKIS 1,3, D. KEMPURAJ1 and M. LYTINAS 1
1 Department of Pharmacology and Experimental Therapeutics, and 2 Internal Medicine, Tufts University School of Medicine, New England Medical Center, 136 Harrison Avenue, Boston, Massachusetts, USA 3 Department of Hematology, Division of Health Sciences, University of Crete, Heraklion, Greece Int. J. Immunopathol. Pharmacol. 14:119, 2001
Flavonoids are low molecular weight compounds rich in seeds, citrus fruits, olive oil, tea and red wine, with potent antioxidant, cytoprotective and antiinflammatory activities. Flavonoids are composed of a three-ring structure (A,B and C) with various substitutions; they can be subdivided according to the presence of an oxy group at position 4, a double bond between carbon atoms 2 and 3 or a hydroxyl group in position 3 of the C (middle) ring. Particular hydroxylation patterns of the Bring of the flavones permit them to inhibit histamine, tryptase, interleukin-6 and interleukin-8 release from human umbilical-cord derived cultured mast cells, as well as from macrophages. The catechol (o-dihydroxy) group in the B ring as in quercetin confers potent inhibitory ability, while a pyrogallol (trihydroxy) group, as in myricetin, produces even higher activity. However, addition of one hydroxyl group on position 2' of the B ring, as in the flavonol morin, renders this compound inactive. The C2-C3 double bond of the C ring appears to increase scavenger activity because it confers stability to the phenoxy-radicals produced, while the 4-oxo (keto double bond at position 4 of the C ring) increases free radical scavenger activity by delocalizing electrons from the B ring. The 3-OH group on the C ring appears tobe critical for anti-inflammatory activity. Inhibition of mast cell secretion was shown to be mediated by a 78-kD phosphoprotein which has been cloned and serves as a bridge between the cell surface and the cytoskeleton. Phosphorylation at particular sites in the C-terminus unfolds the three dimensional structure of this protein making actin binding sites accessible; crosslinking with actin in the cytoskeleton prevents secretion of inflammatory mediators. These properties present unique opportunities for the synthesis of new compounds for the treatment of inflammatory and possibly proliferative disorders.
Key words: allergy, flavonoids, inflammation, mast cells, secretion
Arkadiusz ORZECHOWSKIa*, Katarzyna GRZELKOWSKAa, Wioletta ZIMOWSKAa, Jerzy SKIERSKIb, Tomasz PLOSZAJa**, Katarzyna BACHANEKa, Tomasz MOTYLa, Wojciech KARLIKa, Marcin FILIPECKIc
a Department of Physiology, Biochemistry, Pharmacology and Toxicology, Faculty of Veterinary Medicine, Warsaw Agricultural University, Nowoursynowska 166, 02-787 Warsaw, Poland
b Flow Cytometry Laboratory, Drug Institute, Warsaw, Poland
c Department of Plant Genetics and Breeding in Horticulture, Warsaw Agricultural University, Warsaw, Poland
Reprod. Nutr. Dev. 40 (2000) 441–465
Abstract — Polyphenol quercetin induced apoptosis in proliferating murine L1210 lymphocytic cells. DNA damage, as well as apoptosis and withdrawal from the cell cycle were transient. The above mentioned death promoting activity of quercetin was enhanced by physiological concentrations of TNF-α. At the same time, indices of cell viability dropped. However, the extent and tendency of the initially enhanced cell mortality steadily diminished throughout the experiment. After 12 h the G2/M phase reappeared. After 24 h all indices almost returned to control levels indicating either the selection of subpopulation of unaffected leukaemic cells or cells developing resistance to the treatment. A DNA ladder of oligonucleosomes was observed for apoptogenic treatments. We conclude that quercetin unmasked cell death, promoting the activity of TNF-α. However, after 12 and 24 h of exposure, surviving cells could complete the cell cycle and finally recover. At the same time, increased NF-kB activation was demonstrated by immunoblotting of the immunoreactive RelA/p65 subunit in nuclear extracts. Exposure to TNF-α or quercetin was crucial for increased activity of NF-kB, which may implicate an increasing resistance to their cytotoxicity.
quercetin / TNF-α / leukaemia / apoptosis / NF-kB
Kazuo Nakagawa,* Michiyo Kawagoe, Masako Yoshimura, Hiroko Arata, Tomoka Minamikawa, Miho Nakamura, and Akiko Matsumoto
Department of Food Science, Kyoto Women’s University, Higashiyama-ku, Kyoto 605–8501, Japan
Journal of Health Science, 46(6)(2000)
We evaluated the efficacy of flavonoid quercetin as an antioxidant in hepatic lysosomal fractions of mice using the hydrophilic radical generator 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) and the lipophilic radical generator 2,2′-azobis(2,4-dimethylvaleronitrile) (AMVN). Quercetin inhibited lipid peroxidation in lysosomal fractions, measured as thiobarbituric acid reactive substances (TBARS), and inhibited the release of lysosomal enzymes more obviously against AAPH than against AMVN. Whereas inhibitory effects of quercetin on lipid peroxidation were weaker than those of the synthetic lipophilic antioxidant 2,6-di-tert-butyl-p-cresol (BHT), lysosomal fractions preloaded with quercetin effectively quenched 1,1-diphenyl-2-picrylhydrazyl radicals, similar to BHT. Rutin, a glycoside of quercetin, was less potent than quercetin in these experiments. These findings suggest that quercetin could have potent antioxidative activity in the spaces between an aqueous phase and a lipid phase in biological systems owing to the localization within membranes as well as evident antioxidative activity.
Key words —–— quercetin, lipid peroxidation, antioxidant, flavonoid, radical scavenger, biomembrane
Reiner Strick*†, Pamela L. Strissel*†, Susanne Borgers, Steve L. Smith, and Janet D. Rowley
University of Chicago, Department of Medicine, Section of HematologyyOncology, Chicago, IL 60637
PNAS April 25, 2000 u vol. 97 u no. 9
Chromosomal translocations involving the MLL gene occur in about 80% of infant leukemia. In the search for possible agents inducing infant leukemia, we identified bioflavonoids, natural substances in food as well as in dietary supplements, that cause site-specific DNA cleavage in the MLL breakpoint cluster region (BCR) in vivo. The MLL BCR DNA cleavage was shown in primary progenitor hematopoietic cells from healthy newborns and adults as well as in cell lines; it colocalized with the MLL BCR cleavage site induced by chemotherapeutic agents, such as etoposide (VP16) and doxorubicin (Dox). Both in vivo and additional in vitro experiments demonstrated topoisomerase II (topo II) as the target of bioflavonoids similar to VP16 and Dox. Based on 20 bioflavonoids tested, we identified a common structure essential for topo II-induced DNA cleavage. Reversibility experiments demonstrated a relegation of the bioflavonoid as well as the VP16-induced MLL cleavage site. Our observations support a two-stage model of cellular processing of topo II inhibitors: The first and reversible stage of topo II-induced DNA cleavage results in DNA repair, but also rarely in chromosome translocations; whereas the second, nonreversible stage leads to cell death because of an accumulation of DNA damage. These results suggest that maternal ingestion of bioflavonoids may induce MLL breaks and potentially translocations in utero leading to infant and early childhood leukemia.
☺ Human metabolic pathways of dietary flavonoids and cinnamates -PDF file
G. Williamson, A. J. Day, G. W. Plumb and D. Couteau
Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, U.K.
Biochemical Society Transactions (2000) Volume 28, part 2
Abstract: Flavonoids and cinnamates are widespread phenolic secondary metabolites synthesized by plants for defensive purposes. Many foods and beverages contain high levels of phenolic compounds. Certain phenolics in the diet are particularly bioactive and have pronounced effects on mammalian cells. These effects, together with epidemiological studies and animal models, have led to the hypothesis that dietary phenolics contribute to the health bene®ts of a diet rich in fruit and vegetables. This paper examines the biochemistry of the uptake and metabolic route of two groups of plant phenolics, the avonols and hydroxycinnamates.
Key words: chlorogenic acid, diet, glycosidase, metabolism, phenolic.
Yumiko Nakamura,* Susumu Ishimitsu, and Yasuhide Tonogai
Division of Food Chemistry, National Institute of Health Sciences, Osaka Branch, 1–1–43, Hoenzaka, Chuo-ku, Osaka 540–0006, Japan
Journal of Health Science, 46(4) 2000
Effects of quercetin and rutin on serum and hepatic lipid concentrations, fecal steroid excretion and their antioxidant properties were investigated in rats by oral administration. No toxic symptom was observed even at the dose of 1.0 g/kg of quercetin or rutin. Serum and hepatic lipid concentrations and fecal steroid excretion was not influenced remarkably, but serum thiobarbituric acid reactive substances (TBARS) decreased dose-dependently with the administration of quercetin or rutin. The decrease of serum TBARS was significantly correlated with the increase of serum free flavonoids (p < 0.05–0.001). Serum flavonoid concentrations, especially free quercetin, were higher in rutin-administered rats than in quercetin-administered rats at doses of 1.0 g/kg for 10 d (p < 0.05–0.001). When 1.0 g/kg of quercetin or rutin was administered in a single dose, they remained in the blood as aglycone or their conjugates of quercetin and isorhamnetin, even three days after administration. Recovered flavonoids were only 0.13% and 0.89% in urine for 3 d and 0.03% and 0.13% in serum on day 3 by administration of quercetin and rutin, respectively. Thus, some part of the administered quercetin or rutin was metabolized and showed antioxidant property, but had no remarkable influence on serum or hepatic lipid concentrations or fecal steroid excretion in rats.
Key words —–— quercetin, rutin, rat, flavonoid, thiobarbituric acid reactive substance, steroid excretion
☺ Protective effects of quercetin during influenza virus-induced oxidative stress -PDF file
Telugu Akula Narasa Raju1 MSc, Ayyagari Naga Vijaya Lakshmi1 MSc, Tamatam Anand1 MSc, Linga Venkateshwar Rao1 MSc, PhD and Gita Sharma2 MSc, PhD
1Department of Microbiology, Osmania University, Hyderabad, India
2Biotechnology Division, Zydus Cadila Healthcare Research Centre, Ahmedabad, India.
Oxidative stress was found to have a role in many viral diseases including AIDS, hepatitis and influenza. In the present study the pathology of influenza viral infection in the lungs, which may lead to oxidative stress, was investigated and an attempt was made to study the efficacy of anti-oxidants as therapeutic agents. Adult male mice of Swiss albino type were infected with influenza virus (A/Hong Kong/8/68) and studied for the antioxidant status in the lungs by evaluating the lung enzymatic anti-oxidant system including superoxide dismutase and catalase. Superoxide radical generation, which might increase by the activated alveolar macrophages, was estimated by nitroblue-tetrazolium reduction assay. We have also estimated lipid peroxidation levels in lung through thiobarbutiric acid reactive substances assay. We also examined the ability of flavonoid quercetin in protecting from influenza virus-induced oxidative stress. The influenza-infected group showed decreased levels of superoxide dismutase and catalase; however, anti-oxidant supplemented groups showed these activities to be the same as in the control group. The lipid peroxide levels were increased in virus-infected mice. Administration of quercetin lowered the lipid peroxide levels significantly. Formazan positive cells were increased by 80% in the virus-infected group and supplementation with quercetin reduced their number to 44%.
Key words: anti-oxidants, influenza virus, oxidative stress, quercetin.
☺Structural Determination of Flavonoids: The Power of MSn -PDF file
Jack Cunniff, Philip Tiller, Michael Harvey, and Adrian Land, Finnigan
ThermoQuest LC/MS Application Report
Introduction: For more than five thousand years tea has been used in China as an herbal remedy. In recent years pharmacological studies have supported some of these health claims. Flavonoids, a class of polyphenolic compounds, found in tea, plants and many fruits have shown some promising results related to anti-cancer as well as anti-inflammatory and anti-allergy properties. For these reasons, there has been renewed interest in both detecting and characterizing these compounds. In many instances, flavonoids exist as their glycosylated conjugate. In a typical MS/MS experiment, glycosylated moieties may be cleaved from the molecular precursor with a resulting MS/MS spectrum which is difficult to relate back to a hypothetical structure. The primary reason for the difficulty is the fact that first generation fragment ions may undergo further fragmentation, which can result in a very complex spectrum. Third and fourth generation product ions can not readily be distinguished from second generation product ions. The Finnigan LCQ DECA and LCQ and can perform MSn, so precursor ions are isolated before a subsequent MS/MS experiment is performed. Due to this isolation step, fragmentation spectra are generally less complex and ambiguous than traditional MS/MS spectra. Through successive MS/MS steps, product origins can be assigned. As the following experiments will show, the LCQ DECA or LCQ may “remove” glycosylated side chains in a controlled, step-by-step manner using the power of MSn. Eventually, a core structure is exposed. A final fragmentation spectrum of the core structure yields a classic fingerprint which may then be referenced against a library MS/MS spectrum of the base component. In this way, a compound may be unequivocally classified.
☺Flavonoids Promote Haustoria Formation in the Root Parasite Triphysaria versicolor -PDF file
Huguette Albrecht, John I. Yoder*, and Donald A. Phillips
Department of Vegetable Crops (H.A., J.I.Y.), and Department of Agronomy and Range Science (D.A.P.), University of California, Davis, California 95616–8746
Plant Physiology, February 1999, Vol. 119,
Parasitic plants in the Scrophulariaceae develop infective root structures called haustoria in response to chemical signals released from host-plant roots. This study used a simple in vitro assay to characterize natural and synthetic molecules that induce haustoria in the facultative parasite Triphysaria versicolor. Several phenolic acids, flavonoids, and the quinone 2,6-dimethoxy- p-benzoquinone induced haustoria in T. versicolorroot tips within hours after treatment. The concentration at which different molecules were active varied widely, the most active being 2,6-dimethoxy- p-benzoquinone and the anthocyanidin peonidin. Maize ( Zea mays) seeds are rich sources of molecules that induce T. versicolor haustoria in vitro, and chromatographic analyses indicated that the active molecules present in maize-seed rinses include anthocyanins, other flavonoids, and simple phenolics. The presence of different classes of inducing molecules in seed rinses was substantiated by the observation that maize kernels deficient in chalcone synthase, a key enzyme in flavonoid biosynthesis, released haustoria-inducing molecules, although at reduced levels compared with wild-type kernels. We discuss these results in light of existing models for host perception in the related parasitic plant Striga.
Jette F Young, Salka E Nielsen, Jóhanna Haraldsdóttir, Bahram Daneshvar, Søren T Lauridsen, Pia Knuthsen, Alan Crozier, Brittmarie Sandström, and Lars O Dragsted
1999;69:87–94. American Society for Clinical Nutrition
ABSTRACT Background: Epidemiologic studies suggest that foods rich in flavonoids might reduce the risk of cardiovascular disease. Objective: Our objective was to investigate the effect of intake of flavonoid-containing black currant and apple juice on urinary excretion of quercetin and on markers of oxidative status. Design: This was a crossover study with 3 doses of juice (750, 1000, and 1500 mL) consumed for 1 wk by 4 women and 1 man corresponding to an intake of 4.8, 6.4, and 9.6 mg quercetin/d. Results: Urinary excretion of quercetin increased significantly with dose and with time. The fraction excreted in urine was 0.29–0.47%. Plasma quercetin did not change with juice intervention. Plasma ascorbate increased during intervention because of the ascorbate in the juice. Total plasma malondialdehyde decreased with time during the 1500-mL juice intervention, indicating reduced lipid oxidation in plasma. Plasma 2-amino-adipic semialdehyde residues increased with time and dose, indicating a prooxidant effect of the juice, whereas erythrocyte 2-aminoadipic semialdehyde and g-glutamyl semialdehyde concentrations, Trolox-equivalent antioxidant capacity, and ferric reducing ability of plasma did not change. Glutathione peroxidase activity increased significantly with juice dose. Conclusions: Urinary excretion of quercetin seemed to be a small but constant function of quercetin intake. Short-term, high intake of black currant and apple juices had a prooxidant effect on plasma proteins and increased glutathione peroxidase activity, whereas lipid oxidation in plasma seemed to decrease. These effects might be related to several components of the juice and cannot be attributed solely to its quercetin content. KEY WORDS: Quercetin, urinary excretion, biomarker, human intervention, antioxidative status, malondialdehyde, protein oxidation, apple juice, black currant juice, glutathione peroxidase, flavonoids
☺ Anthocyanins and other flavonoids -PDF file
J. B. Harborne and C. A. Williams
Plant Science Laboratories, University of Reading, Reading, UK, RG6 6AS
Natural Product Reports, 1998
☺Accumulation of flavonoids and related compounds in birch induced by UV-B irradiance -PDF file
ANU LAVOLA
Department of Biology, University of Joensuu, P.O. Box 111, SF-80101 Joensuu, Finland
TREE PHYSIOLOGY VOLUME 18, 1998
Summary A growth chamber experiment was conducted to examine the effects of UV-B exposure (4.9 kJ m-2 day-1 of biologically effective UV-B, 280--320 nm) on shoot growth and secondary metabolite production in Betula pendula (Roth) and B. resinifera (Britt.) seedlings originating from environments in Finland, Germany and Alaska differing in solar UV-B radiation and climate. Neither shoot growth nor the composition of secondary metabolites was affected by UV-B irradiance, but the treatment induced significant changes in the amounts of individual secondary metabolites in leaves. Leaves of seedlings exposed to UV-B radiation contained higher concentrations of several flavonoids, condensed tannins and some hydroxycinnamic acids than leaves of control seedlings that received no UV-B radiation. At the population level, there was considerable variation in secondary metabolite responses to UV-B radiation: among populations, the induced response was most prominent in Alaskan populations, which were adapted to the lowest ambient UV-B radiation environment. I conclude that solar UV-B radiation plays an important role in the formation of secondary chemical characteristics in birch trees.
Keywords: Betula pendula, Betula resinifera, birch populations, phenolic acids, tannins, ultraviolet-B radiation.
☺Estrogenic Activity of Dietary Flavonoids -PDF file
Detection of Weak Estrogenic Flavonoids Using a Recombinant Yeast Strain and a Modified MCF7 Cell Proliferation Assay
Vibeke Breinholt* and John Christian Larsen
Institute of Food Safety and Toxicology, Division of Biochemical and Molecular Toxicology,
The Danish Veterinary and Food Administration, Mørkhøj Bygade 19, 2860 Søborg, Denmark Chem. Res. Toxicol. 1998, 11, 622-629
A newly developed recombinant yeast strain, in which the human estrogen receptor has been stably integrated into the genome of the yeast, was used to gain information on the estrogenic activity of a large series of dietary flavonoids. Among 23 flavonoids investigated, 8 were found to markedly stimulate the transcriptional activity of the human estrogen receptor in the yeast assay increasing transcriptional activity 5-13-fold above background level, corresponding to EC50 values between 0.1 and 25 íM. Five compounds increased the transcriptional activity 2-5-fold over the control, with EC50 values ranging from 84 to 102 íM, whereas the remaining flavonoids were devoid of activity. The most potent flavonoid estrogens tested were naringenin, apigenin, kaempferol, phloretin, and the four isoflavonoids equol, genistein, daidzein, and biochanin A. With the exception of biochanin A, the main feature required to confer estrogenicity was the presence of a single hydroxyl group in the 4¢-position of the B-ring of the flavan nucleus, corresponding to the 4-position on phloretin. The estrogenic potency of the flavonoids was found to be 4 000-4 000 000 times lower than that observed for 17â-estradiol, when compared on the basis of EC50 values. The estrogenic activity of the dietary flavonoids was further investigated in estrogen-dependent human MCF7 breast cancer cells. In this system several of the flavonoids were likewise capable of mimicking natural estrogens and thereby induce cell proliferation. Similar structural requirements for estrogenic activity were found for the two assays. The present results provide evidence that several of the flavoestrogens possess estrogenic properties comparable in activity to the well-established isoflavonoid estrogens. The use of Alamar Blue, a vital dye which is metabolically reduced by cellular enzymes to a fluorescent product, was found to greatly simplify the MCF7 cell-based estrogen screen, making this mammalian assay applicable as a large-scale screening tool for estrogenic compounds.
PLTM Karin Janssen, Ronald P Mensink, Frank JJ Cox, Jan L Harryvan, Robert Hovenier, Peter CH Hollman, and Martijn B Katan
1998;67:255–62. American Society for Clinical Nutrition
ABSTRACT: Intake of dietary flavonols and flavones was inversely associated with risk for cardiovascular disease in several epidemiologic studies. This may have been due to effects on hemostasis because flavonoids have been reported to inhibit platelet aggregation in vitro. We indeed found that 2500 mmol/L of the flavonol quercetin and the flavone apigenin significantly inhibited collagen- and ADP-induced aggregation in platelet-rich plasma and washed platelets by <80–97%. However, lower concentrations, such as might occur in vivo, had no effect. To test this in vivo we fed 18 healthy volunteers 220 g onions/d providing 114 mg quercetin/d, 5 g dried parsley/d providing 84 mg apigenin/d, or a placebo for 7 d each in a randomized crossover experiment with each treatment period lasting 2 wk. Onion consumption raised mean plasma quercetin concentrations to 1.5mmol/L; plasma apigenin could not be measured. No significant effects of onions or parsley were found on platelet aggregation, thromboxane B2 production, factor VII, or other hemostatic variables. We conclude that the antiaggregatory effects of flavonoids seen in vitro are due to concentrations that cannot be attained in vivo. Effects of dietary flavonols and flavones on cardiovascular risk are possibly not mediated by hemostatic variables.
KEY WORDS Apigenin, diet, factor VII, fibrinogen, flavonoid, hemostasis, humans, plasminogen activator inhibitor 1, PAI-1, plasminogen, platelet aggregation, quercetin, thromboxane, in vitro study, onions, parsley
☺ Plasma concentrations and urinary excretion of the antioxidant -PDF file
flavonols quercetin and kaempferol as biomarkers for dietary intake
Jeanne HM de Vries, Peter CH Hollman, Saskia Meyboom, Michel NCP Buysman, Peter L Zock, Wija A van Staveren, and Martijn B Katan
ABSTRACT Flavonols are antioxidants that may reduce the risk of heart disease. Two major flavonols in the diet are quercetin and kaempferol, and their main sources in the Netherlands are tea and onions. We investigated whether plasma concentrations and urinary excretion of quercetin and kaempferol in humans could be used as biomarkers of intake. We provided 15 subjects with strong black tea (1600 mL/d) or fried onions (129g/d) for 3 d each in random order separated by a 4-d washout period. The tea provided 49 mg quercetin and 27 mg kaempferol daily and the onions provided 13 mg quercetin and no kaempferol. Flavonols from both foods were clearly absorbed. However, the excretion of unmodified quercetin was 0.5% of intake after tea and 1.1% after onions. Thus, the absorption of quercetin from tea was half of that from onions. The onion treatment was repeated 7–14 d later to estimate within-subject CVs as a measure of reproducibility when the same treatment is given twice. CVs for quercetin were 30% in plasma and 42% in urine. The magnitude of these variations relative to actual variations of <60% between free-living subjects indicates that concentrations of quercetin in plasma and urine are applicable as biomarkers of its intake. We conclude that flavonols in plasma and urine reflect short-term flavonol intake and that they could be used as biomarkers to distinguish between high and low flavonol consumption in epidemiologic studies.
KEY WORDS Quercetin, kaempferol, flavonols, flavonoids, dietary assessment, excretion, tea, onions, reproducibility, biomarker
☺ On the photosensitized formation of 1O2 (1∆2) by flavonoids -PDF file
Eugeny A. Venedictov* and Olga G. Tokareva
Institute of Chemistry of Non-Aqueous Solutions, Russian Academy of Sciences, 153045 Ivanovo, Russian Federation.
Mendeleev Communications Electronic Version, Issue 2. 1997 (pp. 47–86)
The quantum yields of the photosensitized formation of singlet molecular oxygen from luminescence experiments in benzene solutions of 3,5,7,3',4'-pentamethoxyflavone, 3-hydroxy-5,7,3',4'-tetramethoxyflavone and 5-hydroxy-3,7,3',4'-tetramethoxyflavone were found to be 0.49±0.05 and < 10–2, respectively.
☺ Seabuckthorn flavonoids and their medical value -PDF file
Zhao Yuzhen Wu Fuheng
(Institute of Information, Shanxi Academy of Agriculture Science, Taiyuan, 030031)
Hippophae, 1997, vol. 10(1), pp39-41.
Abstract: In this paper, we briefly described the contents, types, extraction methods and medical value of Seabuckthorn flavonoids.
Key words: Seabuckthorn Flavonoids Medical application and development
☺ Catechol-O-methyltransferase-catalyzed Rapid O-Methylation of Mutagenic Flavonoids -PDF file
METABOLIC INACTIVATION AS A POSSIBLE REASON FOR THEIR LACK OF CARCINOGENICITY IN VIVO*
Bao Ting Zhu, Edward L. EzellS, and Joachim G. LiehrQ
From the Department of Pharmacology and Toxicology and the $Department of Human Biochemistry and Genetics, The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-1031
☺ IRON AND COPPER CHELATION BY FLAVONOIDS – AN ELECTROSPRAY MASS SPECTROMETRY STUDY
M. Tereza Fernandeza∗, M. Lurdes Miraa,b, M. Helena Florêncioa and Keith R. Jenningsc
aDepartamento de Química e Bioquímica, Faculdade de Ciências da Universidade de
Lisboa, Edifício C8, 1749-016 Lisboa, Portugal.
bCentro de Metabolismo e Endocrinologia da Faculdade de Medicina de Lisboa,
Laboratório de Genética, Faculdade de Medicina de Lisboa, 1600 Lisboa, Portugal.
cDepartment of Biological Sciences, Warwick University, Coventry CV4 7AL, UK.
Abstract: Flavonoids are well known as effective free radical scavengers exhibiting therefore an antioxidant behaviour. Another antioxidant mechanism however may result from the ability they have to chelate metal ions, rendering them inactive to participate in free radical generating reactions. Electrospray mass spectrometry has been used to study metal ion interactions with a set of flavonoids from different classes. Complexes with a range of stoichiometries, of metal: flavonoid, 1:1, 1:2, 2:2, 2:3 have been observed. The stoichiometry 1:2 is in general the preferred one. It is established for flavones and for the flavanone naringenin that the binding metal sites are preferentially at the 5-hydroxyl and 4-oxo groups. Redox reactions are also observed through the change of the oxidation state of the metal, jointly with the oxidation of the flavonoid by loss of hydrogen. Structures of the oxidized species of some flavonoids are proposed.
Keywords: Flavonoids; Metal-Chelation; Electrospray Mass Spectrometry; Antioxidants
☺ Recurrent Hyperin°ations and Learning -PDF file
Albert Marcet Universitat Pompeu Fabra (Barcelona), CREI and CEPR and
Juan Pablo Nicolini¤ Universidad Torcuato di Tella (Buenos Aires) November 23, 2001
Abstract: This paper uses a model of boundedly rational learning to account for the observations of recurrent hyperin°ations in the last decade. We study a standard monetary model where the fully rational expectations assumption is replaced by a formal de¯nition of quasi-rational learning. The model under learning is able to match remarkably well some crucial stylized facts observed during the recurrent hyperin°ations experienced by several countries in the 80's. We argue that, despite being a small departure from rational expectations, quasirational learning does not preclude falsi¯ability of the model, it does not violate reasonable rationality requirements and it can be used for policy evaluation.
Keywords: Hyperin°ations, convertibility, stabilization plans, quasi-rationality. JEL classi¯cation: D83, E17, E31.
☺ QUERCETIN 30 ABSTRACTS -PDF file
☺ Analysis of Flavonoids in Phytopharmaceutical Products by Capillary Electrophoresis in Combination with Electrospray Mass Spectrometry
1 1 2 1 2 C.W. Huck , G. Stecher , W. Ahrer , W.M. Stöggl , W. Buchberger , 1 G.K. Bonn
1 Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innrain 52a, 6020-Innsbruck, Austria
2 Department of Analytical Chemistry, University of Linz, Altenbergerstraße 69, 4040- Linz, Austria
Abstract
Complex extracts of plants often require very effective separation techniques to allow the elucidation of pharmacologically relevant compounds. CE coupled to MS detection can provide structure-selective information about the analytes in such matrices and has turned out to be an attractive alternative to HPLC methods. Therefore, a CE method has been established for the analysis of a flavonoid-mixture consisting of 5-methoxy-flavone, biochanin A, hesperetin and naringenin obtained from plant extracts.
ACADEMIC DISSERTATION
To be presented, with the permission of the Faculty of Agriculture and Forestry of the University of Helsinki, for Public criticism in Auditorium XII, University Main Building, on November 8, 2002, at 12 o’clock.
Department of Health and Functional Capacity, National Public Health Institute
Department of Applied Chemistry and Microbiology, University of Helsinki
ABSTRACT
Flavonoids are phenolic compounds widely present in plants and foods of plant origin. Experimental and epidemiological studies have suggested a protective role for the compounds on human health, but until recently, because methods for their analysis in tissues were lacking, knowledge about their bioavailability, pharmacokinetics and metabolic fate in humans was limited. The primary aims of the studies presented in this thesis were to develop methods suited for the analysis of the flavonoids quercetin, hesperetin and naringenin in human plasma and urine. Other aims were to investigate their bioavailability, pharmacokinetics and use as biomarkers of intake. The compounds were chosen on the basis of experimental and epidemiological evidence, and dietary intake. The analytical methods developed allowed the analysis of low concentrations of quercetin in plasma, and hesperetin and naringenin in plasma and urine, with good reproducibility. The methods were based on solid-phase and liquid-liquid extraction and high-performance liquid chromatography with electrochemical detection. The pharmacokinetics and bioavailability of quercetin were studied in subjects ingesting single doses of quercetin aglycone and rutin, and in subjects consuming berries or their habitual diets for several weeks. In the first human study, healthy volunteers received three different doses of quercetin aglycone or rutin orally in a double-blind, diet-controlled, cross-over setting. The overall kinetic behaviour of quercetin differed after the two treatments, although the mean Cmax and AUC(0-32) values were similar. Quercetin from quercetin aglycone was absorbed rapidly from the upper parts of the gastrointestinal tract, while quercetin from rutin appeared to be absorbed from the distal parts of the small intestine or the colon. Especially after ingestion of rutin, marked variation in plasma levels occurred. Furthermore, quercetin from rutin was more bioavailable in women than in men. T1/2 of quercetin ranged between 15 and 18 h. In the second human study, middle-aged men consumed 100g/day in total of lingonberries, black currants and bilberries for two months, or their habitual diets. Plasma quercetin concentrations were 30-50% higher in the berry group than in the control. When the men were still on their habitual diets, the mean plasma concentration was 16 ± 13 µg/l. The pharmacokinetics and bioavailability of the flavanones hesperetin and naringenin were investigated in a study where healthy volunteers ingested 400-760 ml of orange juice or grapefruit juice once. Relatively high concentrations of flavanones were reached in plasma, but interindividual variation in plasma levels was marked. Both flavanones appeared to be absorbed from the distal parts of the small intestine or the colon, and their plasma half-lifes were similar (1-2 h). The mean urinary recovery of naringenin was 1% from orange juice and 30% from grapefruit juice. The corresponding value for hesperetin from orange juice was 5%. These values are minimum estimates for bioavailability. The results of the studies indicate that plasma quercetin is a fairly good biomarker of intake. Its plasma concentrations increase with increasing dose, and it has a comparatively long half-life. It is also bioavailable from a typical Finnish diet. Fasting plasma and especially urine flavanone levels, by contrast, appear to be less useful as biomarkers of intake. In conclusion, methods for the analysis of quercetin, hesperetin and naringenin inhuman plasma and urine were developed. Quercetin was shown to be bioavailable from capsules, berries and the diet, and hesperetin and naringenin from citrus juices.
☺ Anthocyanins and other flavonoids1 -PDF file
Jeffrey B. Harborne and Christine A. Williams
Plant Science Laboratories, The University of Reading, Reading, UK RG6 6AS
Received (in Cambridge, UK) 22nd January 2001
First published as an Advance Article on the web 5th April 2001
☺ Effect of Dietary Quercetin on Pork Quality -PDF file
Brian T. Kremer, Ph.D. candidate; Tim S. Stahly, professor; and Joseph G. Sebranek, professor Department of Animal Science Iowa State University
The Lipid Research Laboratory, Technion Faculty of Medicine, The Rappaport Family Institute for Research in the Medical Sciences and
Rambam Medical Center, Haifa, Israel.
Introduction: Atherosclerosis, the major cause of cardiovascular diseases is accelerated under oxidative stress (which also causes LDL oxidation). Thus, diet rich in antioxidants is recommended in order to attenuate LDL oxidation and atherosclerosis development. The lipophylic antioxidants vitamin E and carotenoids however were found to be non effective in reducing atherosclerosis events in humans. In contrast , polyphenolic flavonoids found in several fruits and vegetables, are mostly hydrophylics , they are potent antioxidants and anti-atherosclerotic agents. We thus analyzed and compared the polyphenols content ,the free radicals scavenging capacity and the ability to reduce LDL oxidation of several juices obtained from fruits.
K.E. Joung and Y.Y. Sheen
College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea
We have examine the estrogenic activites of flavonoids using pERE-Luc and pCYP1A1-Luc reporter system. MCF-7 humans breast cancer cells were stably transfected with pERE-Luc and Hepa I cells were transfected with pCYP1A1-Luc. Estradiol (E2) and synthetic estrogen, diethylstylbesterol (DES) were induced luciferase activity in dose dependent manner and their induced activities were decreased by tamoxifen (Tam) treatment. A large series of flavonoids showed estrogenic activities and there were some relationship between their structure and activity. First, 4-methoxylation and catechol structure decreased estrogenic activities. Second, hydroxylation of 3 position reduced estrogenic effect. Third, glycosides of flavonoids showed weak estrogenic activity or no activity. Interestingly, when tested at high concentrations, genistein, kaempferol, biochanin A and chrysin elicited luciferase induction higher than
that of the maximum induction by estradiol. And these effect of genistein and kaempferol could not be fully inhibited with tamoxifen. [Supported by the Ministry of Environment of Korea]
☺ In vitro studies indicate: Quercetin-3-O-ß-Dglucuronopyranoside (miquelianin) is able to reach the CNS from the small intestine
Westfälische Wilhelms- University of Münster GA-Symposium 31.08.03 - 04.09.03 in Kiel
G. Jürgenliemk, K. Boje, S. Hüwel*, C. Lohmann*, H.-J. Galla*, A. Nahrstedt
Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Hittorfstr. 56, 48149 Münster, Germany
*Institute of Biochemistry, University of Münster, Wilhelm-Klemm-Str. 2, 48149 Münster, Germany
☺ Microquantitaive determination of iodine and quercetin under non-equilibrium conditions
S. Milenković, M. Mijatović, N. Pejić*, S. Anić, V. Vukojević and Lj. Kolar-Anić
Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, P. O. Box 137, YU-11001 Belgrade, Yugoslavia
*Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, YU-11000 Belgrade, Yugoslavia
Kanji Ishimaru and Etsuko Matsuura
Faculty of Agriculture, Saga University 1, Honjo, Saga840-8502, Japan
Summary: Four flavonoids (diosmin, linarin, apigenin 7-O-rutinoside and luteolin 7-O-rutinoside) and a polyacetylene ( lobetyolin) were isolated from methanol extracts of whole plantlets of Pratia nummularia , and chemical structures of the isolates were characterized by NMR spectroscopic analysis. In the in vivo cultivated plantlets, flavonoids accumulated mostly in the aerial parts (leaves, stems and fruits) and the polyacetylene was, in contrast, found in the root portion. P. nummularia in vitro shoot cultures produced similar flavonoids (majorly linarin) in both leaves and roots, and illumination promoted only flavonoid accumulation and not polyacetylene production. Hairy root cultures of P. nummularia , induced by infection with Agrobacterium rhizogenes MAFF 03-01724, produced large amounts of polyacetylenes, particularly lobetyolinin, with a concentration almost 5 times that of the parent plants. In the hairy root cultures, illumination promoted accumulation of diosmin and linarin, indicating increased OH group methylation in the B-ring portion of the flavonoids. The concentration diosmin, one of the most well-established anti-cancer natural products in Citrus species, was much larger in P. nummularia in vivo and in vitro than in various Citrus fruits (pericarp and pulp). P. nummularia tissues, producing large amounts of flavonoids, demonstrated strong radical scavenging activity (for DPPH), and therefore might be a good resource, applicable in the medicinal and/or food industries, as well as for biosynthetic studies.
☺ PRESSURIZED FLUID EXTRACTIONS OF NINE FLAVONOIDS FROM PROPOLIS AND IN VITRO TESTS -PDF file
C.R. Chen, W.W. Huang a, C.J. Chang*
Department of Chemical Engineering, National Chung Hsing University, Taiwan, ROC
a Department of Biology, China Medical College, Taiwan, ROC *cmchang@dragon.nchu.edu.tw
This study addressed the feasibility of superheated water extraction (SWE) of nine flavonoids from two types of propolis. Some parameters and related procedures for establishing ethanol-soluble and water-soluble propolis are presented. The highest flavonoid content in the extract is obtained when 70 % ethanol aqueous solution was used as the solvent. Extractions using superheated water at elevated pressures were examined to prepare water-soluble propolis. The greatest content of flavonoids in water-soluble extracts was obtained at 800 psig, 120 oC, and when 30 % ethanol was added as cosolvent for 1 hour extraction, according to the Taguchi experimental set-up. Under these conditions for ext raction, 32.3 % total yield of water-soluble propolis was produced from Brazilian lumps. Finally, all extracts were tested for cell viability and cell proliferation to obtain the EC50 value. Many extracts of propolis inhibited the growth of human leukemia cancer cells, for example HL-60 and U937. Experimental results also indicated a relationship between the anti-cancer effect and the flavonoids content of each extract. The effect of marker flavonoids on the cancer cells is investigated.
Keywords: Superheated water, propolis, flavonoids, in vitro test
☺ Studies on Structural-correlation with Antioxidant Activity of Flavonoids (1) -PDF file
Eriko Mikamoa), Yasuyo Okada a), Masanori Semma a), Yoshio Ito a), Takashi Morimotob) and Mikio Nakamura b)
a) School of Pharmaceutical Science, Mukogawa Women's University b) San-Ei Gen F. F. I., Inc.
Keywords: Flavonoid, Antioxidant activity, â-carotene-linoleic acid system, Methoxide, Glycoside
☺ Studies on Structural-correlation with Antioxidant Activity of Flavonoids (2) -PDF file
Eriko Mikamoa), Yasuyo Okada a), Masanori Semma a), Yoshio Ito a), Takashi Morimotob) and Mikio Nakamura b)
a) School of Pharmaceutical Science, Mukogawa Women's University b) San-Ei Gen F. F. I., Inc.
Keywords: Flavonoid, Antioxidant activity, â-carotene-linoleic acid system, Hydoroxyl derivative, Structure-activity relationship
Jonathan J. Turnbull, Oxford Centre of Molecular Sciences
Flavonoids are an important class of plant secondary metabolites whose roles include attracting pollinators, defending plants against pathogens, signalling in plant-microbe interactions, protecting plants against UV radiation and aiding seed dispersal. There is also current biomedical interest in flavonoids since they inhibit cell proliferation, are antioxidants and display anti-mutagenic, anti-inflammatory, anti-thrombic and anti-hypertensive effects. The anthocyanin sub-family of flavonoids cause pigmentation and are used as food colourants.
☺ UTILIZATION OF BIOFLAVONOIDS FOR THE DESIGNING OF ANTIOXIDANT–IBUPROFEN MUTUAL PRODRUGS -PDF file
Pritam Dev Sharma, Senthil Kumar Chandiran and Shruti
University Institute of Pharmaceutical Sciences Panjab University, Chandigarh – 160 014, India
Nonsteroidal antiinflammatory drugs (NSAIDs) are widely used for the treatment of pain, fever and various inflammatory ailments. However, long term NSAIDs therapy results in gastric irritation, bleeding and ulcerations. Recent studies have indicated that local generation of various reactive oxygen species (ROS) may be involved in the formation of gastric ulcers associated with NSAIDs therapy. Based on these observations, it has been suggested that coadministration of NSAIDs and antioxidants might decrease the risk of ulcerogenic side effects. However, there are potential advantages in giving such two agents with complementary activities, in the form of single chemical entity i.e. mutual prodrugs which are designed with improved physicochemical properties and release the parent drugs at the site of action.
☺ ANTIMICROBIAL ACTIVITY EVALUATION STUDIES OF NEW HYDROXY FLAVONOIDS -PDF file
M.A. Baseer, M.M.V. Baig and Y.B. Vibhute
P.G. Dept. of Chemistry, Yeshwant College, Nanded, India
Chalcones represent branch point intermediates in the biosynthesis of various classes of flavonoids. They constitute an important group of natural products and have been reported to possess varied biological and pharmacological activities. They are wide spread components in all parts of plants and are important as flower pigments, growth regulators, phytoalexins and animal toxins.
☺ FLAVONOIDS FROM COMMIPHORA WIGHTII
Suad Khamis S. Al-Burtamani and Majekodunmi O. Fatope
Department of chemistry, Sultan Qaboos University, P.O. Box 36, Al-Khod-123, Muscat, Sultanate of Oman
Fax: 968-515469; Email: majek@squ.edu.om
Commiphora wightii (Arn.) Bhandari (Syn. C. mukul Hook ex Stocks) Engl. (Burseraceae) is used in Oman to treat skin diseases, by applying a mixture of its pulverized trunk and water or scented oil to affected parts. Several terpenes, lignans, steroids, furanosesquiterpenes, and guggltetrols have been isolated from the resin or essential oil of Commiphora plants.1,2 In spite of known uses, the contents of the hard wood of the Commiphora plants are hardly reported. In this investigation we report the isolation of known flavonoids, naringenin (1) and 3-hydroxynaringenin (2), from a species of Commiphora for the first time. The structures of the two compounds were determined from interpretation of NMR, EIMS, and UV spectral data. Flavanoids often display antiinflammatory, antihistaminic, antibacterial and antiviral properties.3 The antioxidant activities (%IP) of compounds 1 and 2 were estimated in the DPPH assay. The %IP of the crude ethanol extract, naringenin (1), 3-hydroxynaringenin (2) and gallic acid (control) were 54, 39, 66 and 88% respectively.
Jaakko Mursu, MSc, RD1; Sari Voutilainen, PhD, RD1; Tiina H. Rissanen, MSc, RD1,2; Jyrki K. Virtanen, MSc, RD1; Tarja Nurmi, MSc1; Jukka T. Salonen, MD, PhD1,2 1
Research Institute of Public Health, University of Kuopio, Kuopio, Finland, PO Box 1627, 70211 Kuopio, Finland, Fax +358-17-162 936 (e-mail: jaakko.mursu@uku.fi) 2
The Inner Savo Health Centre, Suonenjoki, Finland. Flavonoids are naturally occurring, water-soluble antioxidant substances found widely distributed in vegetables fruits and beverages such as tea and wine. In epidemiological studies investigating the relationship between flavonoid intake, coronary heart disease (CHD), and stroke the results have been inconsistent. The aim of the present study was to investigate the relationship between one of the main flavonoid, quercetin, intake and the risk of stroke in a population-based sample of middle-aged men. Methods: We studied the association of quercetin intake and the risk of stroke in the prospective Kuopio Ischaemic Heart Disease Risk Factor (KIHD) Study. Subjects were 1950 Finnish men aged 42-60 years with no CHD or stroke examined at baseline. Quercetin intake was assessed by four day food record at study baseline. Results: During an average follow-up time of 12.8 years 112 strokes (81 ischaemic strokes) occurred. The subjects were classified into quarters according to the level of energy-adjusted quercetin intake (<3.2, 3.2-5.4, 5.5-9.2,>9.2 mg/d). In a Cox' proportional hazards' model adjusted for age, examination year, systolic blood pressure, serum LDL and HDL cholesterol, triglycerides, smoking, body mass index and diabetes, men in the highest quarter of quercetin intake had a relative risk of any stroke of 0.58 (95% CI 0.35-0.97) and ischaemic stroke 0.51 (95% CI 0.28-0.96) when compared with the other men. After adjusting for nutritional factors intake of saturated fat, folate, fibre, beta-carotene, vitamin E and C, the men in the highest quarter had a relative risk of stroke of 0.63 (95% CI 0.37-1.06) and ischaemic stroke 0.54 (95% CI 0.29-0.1,03) when compared with the other men. Conclusion: This prospective cohort study in middle-aged men from eastern Finland indicates that high intake of dietary quercetin is associated with decreased risk of ischaemic stroke. The results of this study confirm previous findings showing that a diet dominated by plant-derived foods promotes good cardiovascular health.
☺ THE PROTECTIVE ROLE OF FLAVONOIDS AGAINST TOXIC FACTORS ON PHOSPHOLIPID MEMBRANES -PDF file
JANINA GABRIELSKA1 and MONIKA SOCZYŃSKA-KORDALA2
1Department of Physics and Biophysics, 2Department of Vegetables, Food and Cereal Technology, Agricultural University, Norwida 25, 50-375 Wrocław, Poland
Flavonoids are plant secondary metabolites that insure the proper growth, development and protection of plants. Both in vivo and in vitro, they exhibit a broad biological activity that in many cases is connected with their antioxidative ability. The diversified ring structure of a flavonoid molecule with conjugated double bonds and numerous hydroxyl substituents ensures their antioxidative action. The long exposure of an organism to the action of free radicals induces cell damage on the molecular level, which may result in dangerous diseases. Organic compounds of tin and lead, as follows from our earlier investigations, interact strongly with the lipid phase of biological membranes, modifying their operation, and thus being toxic. This toxicity may also result from some organometallic compounds, e.g. triphenyl- and tributyltin, which are toxic under some conditions. The objective of this research was to estimate the protective role of flavonoids towards liposome phosphatitylcholine membranes exposed to the simultaneous action of free radicals (induced by UV radiation) and the organic forms of tin. The antioxidative ability of flavonoids in vitro (parameter IQ50) was assumed as a measure of their protective role. Moreover, to suggest a possible antioxidation mechanism of flavonoids, their antiradical activity towards the radical DPPH was investigated. Also, the possibility of interaction between components of the system was estimated in the process of flavonoid association with organometallic compounds. The results obtained indicate a high and differentiated antioxidative, antiradical and chelating activity of the antioxidants studied. They suggest a possible mechanism of the antioxidative action of flavonoids as free radical scavengers and chelaters of organometallic compounds. The complexing properties of flavonoids with respect to toxic forms of tin also indicate a possibility of their application as detoxicants.
T. G. Myasoedova*, A. A. Revina**, and N. B. Zharikova*
* Lomonosov Russian University of Chemical Engineering, Moscow, Russia
** Frumkin Institute of Electrochemistry, Moscow, Russia
Received October 14, 1997
Abstract - The absorption capacity for uranyl ions of natural polyphenolic flavonoid quercetin immobilized on various available and cheap supports (cotton fabrics, Dacron, and silica gel of different brands) was studied, and the effect of 60Co radiation on their sorption was evaluated. Sorption of uranyl ions from aqueous solutions by quercetin immobilized on various supports depends predominantly on the support nature, and the highest effect is observed for cellulose supports impregnated with quercetin in the oxidized form. The g-radiation (60Co) activates sorption of UO2 2+ on impregnated nonsterile gauze, and the best result is provided by irradiation of nonsterile gauze directly in the quercetin solution.
E. T. Oganesyan, Yu. A. Mal’tsev, and D. E. Tvorovskii
Pyatigorsk State Pharmaceutical Academy, Pyatigorsk, Russia Received December 6, 1999
Abstract - Semiempirical quantum-chemical calculations were used to study the reactivity of the C2 =C 3 bond in flavones in reaction with hydroxyl radical. The preferred pathway was found to be addition of the radical by C3 . Increased reactivity in the reaction in question of the hydroxy groups on C3 and C4 ` in polyhydroxyflavones was revealed.
☺ THE PROTECTIVE EFFECT OF QUERCETIN-5-SULPHONIC ACID ON THE MEMBRANE ORGANOTIN ADSORPTION -PDF file
Janina Gabrielska, Marek Langner, Stanis³aw Przestalski
Department of Physics and Biophysics, Agricultural University , Wroc³aw, Poland
The toxic effect of organotins depends, among others, on the extent of their adsorption onto the biological membrane. Previous studies showed that diphenyltin is located within the hydrophobic core of the lipid bilayer, whereas more toxic triphenyltin adsorbs onto its surface. Various compound locations within the lipid bilayer implies possible differences in the effect on the biological membrane. The presence of organotins on the membrane surface was estimated from changes in Fluoresceine-PE fluorescence intensity. Organotin adsorption was measured when the membrane contained quercetin-5-sulphonic acid (QSA), quercetin (QW) and sodium salt of morin-5’-sulphonic acid (NaMSA). The presence of QSA in the lipid bilayer causes a substantial decrease in fluorescence changes, suggesting reduced organotin adsorption (above 80%), NaMSA has no apparent effect, and QW seems to enhance organometallic adsorption. Reduced adsorption is a result of both changes in their partition coefficient and complex formations between QSA and organotins in the aqueous phase. All other flavonoids do not cause any measurable changes in fluorescence when added to the lipid bilayer alone.
Iris Erlund, PhD
Biomarker laboratory, National Public Health Institute (KTL) Mannerheimint. 166, 00300 Helsinki, FINLAND