Liquid chromatography/tandem mass spectrometric determination of inhibition of human cytochrome P450 isozymes by resveratrol and resveratrol-3-sulfate

traps-Resveratrol, a phenolic phytoalexin occurring in grapes, wine, peanuts, and cranberries, has been reported to both have anticarcinogenic, antioxidative, phytoestrogenic, and cardioprotective activities, and to be a weak inhibitor of cytochrome P450 (CYP)3A4, which might have significance for drug-drug interactions. Since traps-resveratrol is rapidly converted in vivo to primarily trans-resveratrol-3-sulfate, a rapid, selective, and sensitive method using liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed to investigate human cytochrome P450 inhibition by traps-resveratrol-3-sulfate. Effects of traps-resveratrol and traps-resveratrol-3-sulfate on the metabolism of selective cytochrome P450 substrates (CYP1A2/ethoxyresorufin, CYP2C9/diclofenac, CYP2C19/(S)-mephenytoin, CYP2D6/bufuralol, CYP3A4/testosterone) were monitored using cDNA-expressed human recombinant isozymes. For method validation, LC/MS/MS was used to measure the inhibition of various cytochrome P450 isozymes by different concentrations (0-50 muM) of known selective inhibitors. IC50 values of 3.2, 1.4, 8.9, 0.2, and 0.3 muM were obtained for the standard isozyme inhibitors CYP1A2/furafylline, CYP2C9/sulfaphenazole, CYP2C19/tranylcypromine, CYP2D6/quinidine, and CYP3A4/ketoconazole, respectively, which were in good agreement with literature values. traps-Resveratrol showed IC50 values of 11.6 muM for CYP2C19 and 1.1 muM for CYP3A4, but the IC50 values exceeded 50 muM for all the other CYP isozymes, which indicated no inhibition. No enzyme inhibition was observed for traps-resveratrol-3-sulfate. Our results indicate that traps-resveratrol is a marginal inhibitor of CYP3A4 and a weak inhibitor of CYP2C19, but its major metabolite traps-resveratrol-3-sulfate is not an inhibitor of any of the cytochrome P450 isozymes investigated. Copyright (C) 2003 John Wiley Sons, Ltd.