OBJECTIVETo study major human UGT isoforms involved in trans-resveratrol (TR) phase II metabolism.

METHODtrans-resveratrol and 12 major human UGT isoforms were incubated in vitro and then glucuronic acid metabolites were determined by HPLC-MS, in order to preliminarily analyze the structure and observe the effect of different UGT isoforms on the generation rate of glucuronic acid metabolites.

RESULTIn in vitro metabolic system, two metabolites-4'-O-monoglucuronide resveratrol (M-1) and 3-0-monoglucuronide resveratrol (M-2)-were generated from trans-resveratrol after being catalyzed by UGT. During the cause, generation of M-1 and M-2 were catalyzed by UGT1A1, UGT1A3, 1A8, 1A9 andlA10, whereas only UGT1A6 and 1A7 contributed to the forma-tion of M-2. Both the formation rate of M-1 and M-2 catalyzed by UGT1A1, 1A10 and the formation of M-2 catalyzed by UGT1A8 slowed down with the increasing concentration of substrates, causing the phenomenon of "substrate inhibition".

CONCLUSIONUGT1A1, 1A8, 1A9, 1A10 get involved in the formation of M-1, and of them UGTIA9 is the most important contributor. UGT1A3 also makes small contribution to the formation of M-1 and M-2, while other UGT isoforms show hardly any reaction with the trans-resveratrol phase II metabolites.