AIMTo compare the TAOC of quercetin, rutin, vitamin C, vitamin E in vitro and examine the effect of quercetin on TAOC of rat plasma after intragastric administration.

METHODSFe3+ reducing ability assay, UV spectrum analysis and HPLC analysis were used to measure TAOC of plasma and the contents of quercetin and rutin after intragastric administration.

RESULTSThe TAOC of quercetin was stronger than that of rutin and roughly equal to vitamin C and vitamin E in vitro. After intragastric administration of quercetin (40 mg/kg bw), the TAOC and content of quercetin in rat plasma increased significantly. Vitamin C also increased plasma TAOC significantly, but rutin and vitamin E didn't after intragastric administration. However, there was no remarkable absorption peak of quercetin on HPLC chromatograms and on the other hand, the peak areas of two unknown peaks near quercetin peak were increased after intragastric administration of quercetin.

CONCLUSIONThe antioxidant capacity of quercetin was stronger than rutin and comparable to vitamin C both in vitro and in vivo. After absorption, quercetin is metabolized to its derivatives.