☺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 p