The Durk Pearson & Sandy Shaw^®
Life Extension News^TM
Volume 6 No. 4 • September 2003

Xanthine Oxidase Inhibition by Flavonoids

There are currently some 4000 flavonoids known, of which many have a high potential for xanthine oxidase (XO) inhibition.¹ Black cherries and black cherry juice have been traditionally used to treat gout. They are high in flavonoids, and this may explain why the treatment often works. The authors of a recent paper¹ report the results of a structure-function analysis for flavonoids to find those with the most XO-inhibitory properties. They describe a method for predicting IC50 (50% inhibitory concentration) values of xanthine oxidase very accurately by calculating the contribution of each hydroxyl moiety toward inhibition of XO.

The flavonoids listed by Van Hoorn et al. that have the lowest IC50 values include: chrysin (2.5 µM), apigenin (1.0 µM), luteolin (0.75 µM), kaempferol (2.5 µM), quercetin (1.5 µM), and myricetin (1.5 µM). The IC50 for allopurinol was given as 6.2 µM.

1. Van Hoorn et al. Accurate prediction of xanthine oxidase inhibition based on the structure of flavonoids. Eur J Pharmacol 451:111-8 (2002).