Abstract
In our search for novel materials possessing anti-hyperuricemic effects, we examined immature Citrus unshiu fruit. Extracts of immature C. unshiu fruit showed moderate anti-hyperuricemic effects in a hyperuricemic model; the extract reduced increased serum urate level by 36% at 500 mg/kg, p.o. The extract did not show significant xanthine oxidase inhibitory activity, but the metabolite of the main flavanone glycoside in the fruit, hesperetin, showed potent anti-hyperuricemic effects; hesperetin reduced increased serum urate level by 44% at 200 mg/kg, p.o. Furthermore, hesperetin showed dose-dependent xanthine oxidase inhibitory activity of 52% at 200 μM. Thus, the anti-hyperuricemic effects of immature C. unshiu may be attributed to hesperetin, a metabolite of hesperidin via xanthine oxidase inhibition.
