Conversion of Rutin to Quercetin by Acid Treatment in Relation to Biological Activities

De-glycosylation could be an important process for enhancing the biological activities of flavonoids. In this study we investigated de-glycosylation of rutin by acid treatment by comparing hydrolysis of rutin to quercetin with two different solvents and acid concentrations. Antioxidant activity was measured using chemical methods and biological activities were examined in cell-based systems. Rutin hydrolysis occurred more rapidly when 80% ethanol was used as the reaction solvent (as compared to water), and the rate of hydrolysis accelerated as acid concentrations increased. In reactions of rutin with 0.5 M HCl in 80% ethanol for 3 h, almost all the rutin was converted into quercetin. 2,2-Diphenyl-1-picrylhydrazyl, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activities, and reducing powers were correlated with conversion rate. Protective activity in HepG2 cells, anti-inflammatory activity in RAW264.7 cells, and antiadipogenic activity were increased with increased conversion of rutin to quercetin. This study suggests that de-glycosylation of glycoside flavonoids may increase physiological activity and, therefore, enhance its use in various fields.