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

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Abstract
trans‐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 trans‐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 trans‐resveratrol‐3‐sulfate. Effects of trans‐resveratrol and trans‐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 μM) of known selective inhibitors. IC50 values of 3.2, 1.4, 8.9, 0.2, and 0.3 μM 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. trans‐Resveratrol showed IC50 values of 11.6 μM for CYP2C19 and 1.1 μM for CYP3A4, but the IC50 values exceeded 50 μM for all the other CYP isozymes, which indicated no inhibition. No enzyme inhibition was observed for trans‐resveratrol‐3‐sulfate. Our results indicate that trans‐resveratrol is a marginal inhibitor of CYP3A4 and a weak inhibitor of CYP2C19, but its major metabolite trans‐resveratrol‐3‐sulfate is not an inhibitor of any of the cytochrome P450 isozymes investigated. Copyright © 2003 John Wiley & Sons, Ltd.