Antioxidative effects of quercetin-glycosides isolated from the flower buds of Tussilago farfara L

• Published in: Food and chemical toxicology Vol. 44; no. 8; pp. 1299 - 1307
• Main Authors: Kim, Mi-Ran, Lee, Jeong Yong, Lee, Hyang-Hee, Aryal, Dipendra Kuma, Kim, Yoon Gyoon, Kim, Sang Kyum, Woo, Eun-Rhan, Kang, Keon Wook
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2006; New York, NY Elsevier Science
• Subjects: Animals; Antioxidant; antioxidant activity; Biological and medical sciences; buds; Cell Line; Enzyme Induction - physiology; Flavonoids - chemistry; Flavonoids - isolation & purification; Flavonoids - pharmacology; flowers; Flowers - chemistry; fractionation; free radical scavengers; Free Radical Scavengers - chemistry; Free Radical Scavengers - isolation & purification; Free Radical Scavengers - pharmacology; free radicals; Gene Expression Regulation, Enzymologic - drug effects; glutamate-cysteine ligase; Glutamate-Cysteine Ligase - biosynthesis; Glutamate-Cysteine Ligase - genetics; Glutamate-Cysteine Ligase - metabolism; Glutathione; Glutathione - metabolism; Glutathione S-transferase; glutathione transferase; Glutathione Transferase - biosynthesis; Glutathione Transferase - metabolism; glycosides; Glycosides - chemistry; Glycosides - isolation & purification; Glycosides - pharmacology; Hepatocytes; herbal medicines; Medical sciences; medicinal plants; Molecular Conformation; NF-E2-Related Factor 2 - metabolism; Nitroblue Tetrazolium - chemistry; Nuclear Magnetic Resonance, Biomolecular; nutrition-genotype interaction; Oriental traditional medicine; oxidative stress; plant extracts; quercetin; Quercetin 3- O-β- l-arabinopyranoside; Rats; Superoxides - metabolism; Toxicology; Transcriptional Activation - drug effects; Tussilago - chemistry; Tussilago farfara; Tussilago farfara L; γ-glutamylcysteine ligase; China; γ-glutamylcysteine ligase; Antioxidant; Glutathione S-transferase; Tussilago farfara L; Glutathione; Quercetin 3- O-β- l-arabinopyranoside; Enzyme; Transferases; Flower bud; Flavonoid; Polyphenol; Glutathione transferase; Ligases; Quercetin; Phenols; Isolation; Glycoside; Quercetin 3-O-β-L-arabinopyranoside
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2006.02.007

A bioassay-guided fractionation of the ethylacetate soluble fraction from the flower buds of Tussilago farfara L. (Compositae) yielded two flavonoids, quercetin 3- O-β- l-arabinopyranoside and quercetin 3- O-β- d-glucopyranoside. These two sugar conjugates of quercetin exhibited higher antioxidative activity than their aglycone, quercetin by NBT superoxide scavenging assay. Moreover, treatment with quercetin 3- O-β- l-arabinopyranoside significantly increased the total glutathione (GSH) contents and the protein level of γ-glutamylcysteine ligase (γ-GCL), a key enzyme required for glutathione (GSH) synthesis in a rat hepatocyte cell line. Subcellular fractionation and reporter gene analysis using antioxidant response element (ARE) construct revealed that quercetin 3- O-β- l-arabinopyranoside increased the level of nuclear Nrf2 and reporter activity, and that these were associated with the induction of the γ-GCL gene. After 24 h incubation of cells with quercetin 3- O-β- l-arabinopyranoside, 23% of the glycoside was converted to its aglycone, quercetin, but γ-GCL was not induced by 7 μM (23%) quercetin. These results suggest that the two quercetin-glycosides isolated from T. farfara L. have direct antioxidative properties, and that quercetin 3- O-β- l-arabinopyranoside increases the cellular GSH level by inducing the γ-GCL gene. These novel effects of quercetin-glycosides are suggestive to underlie the potential putative chemopreventive effects of T. farfara L.