Inhibition of xanthine oxidase activity by an oxathiolanone derivative of quercetin

An oxathiolanone derivative of rutin could be produced in the stomach after the ingestion of rutin containing foods, and the oxathiolanone derivative could be hydrolysed to an oxathiolanone derivative of quercetin (quercetin-oxathiolanone) in the intestine. Quercetin-oxathiolanone as well as quercetin inhibited xanthine oxidase. Approximately 0.05 μM quercetin-oxathiolanone inhibited the activity by 50%, whereas 50% inhibition by quercetin was observed at approximately 0.4 μM. The results suggested that quercetin-oxathiolanone can be used as an effective inhibitor of xanthine oxidase and that the ingestion of rutin-rich foods may be useful to prevent the increase in the blood concentration of uric acid.