Effects of Genistein, Apigenin, Quercetin, Rutin and Astilbin on serum uric acid levels and xanthine oxidase activities in normal and hyperuricemic mice

► We assessed the effects of five flavonoids on xanthine oxidase (XO) activities. ► The serum uric acid levels were also measured in normal and hyperuricemia mice. ► XO activities in vitro were not affected but increases or decreases in vivo. ► Serum uric acid levels in mice treated with flavonoids are higher than control. ► The flavonoids are not replacing Allopurinol to reduce serum uric acid levels.