Effects of Ganoderma, Rhodiola and grape seed extracts on the glucuronidation and oral bioavailability of resveratrol in rats.

Herb extracts were shown to inhibit the activity of UDP-glucuronosyltransferases (UGTs) in vitro. However, the actual in vivo effect of the inhibitory ability on oral bioavailability is yet verified. In this study, resveratrol (RES) was used as a model drug to study the effect of three Chinese herb extracts, Ganoderma, Rhodiola and grape seed, on the in vitro and in vivo inhibition of glucuronidation and the in vivo bioavailability of RES. Overall, although herb extracts might show inhibition on glucuronidation of RES in vitro and in vivo, the inhibition of glucuronidation did not necessarily mean to improve the in vivo bioavailability of RES.