The cancer preventative agent resveratrol is converted to the anticancer agent piceatannol by the cytochrome P450 enzyme CYP1B1

Abstract

Resveratrol is a cancer preventative agent that is found in red wine. Piceatannol is a closely related stilbene that has antileukaemic activity and is also a tyrosine kinase inhibitor. Piceatannol differs from resveratrol by having an additional aromatic hydroxy group. The enzyme CYP1B1 is overexpressed in a wide variety of human tumours and catalyses aromatic hydroxylation reactions. We report here that the cancer preventative agent resveratrol undergoes metabolism by the cytochrome P450 enzyme CYP1B1 to give a metabolite which has been identified as the known antileukaemic agent piceatannol. The metabolite was identified by high performance liquid chromatography analysis using fluorescence detection and the identity of the metabolite was further confirmed by derivatisation followed by gas chromatography-mass spectrometry studies using authentic piceatannol for comparison. This observation provides a novel explanation for the cancer preventative properties of resveratrol. It demonstrates that a natural dietary cancer preventative agent can be converted to a compound with known anticancer activity by an enzyme that is found in human tumours. Importantly this result gives insight into the functional role of CYP1B1 and provides evidence for the concept that CYP1B1 in tumours may be functioning as a growth suppressor enzyme.

Figure 1

Molecular structures of resveratrol, piceatannol, estradiol, and 4-hydroxyestradiol. (A) Shows the conversion of resveratrol to piceatannol catalysed by CYP1B1. (B) Mapping of the phytoestrogen resveratrol onto the steroid framework of estradiol. (C) Shows the CYP1B1 catalysed aromatic hydroxylation of estradiol to 4-hydroxyestradiol.

Figure 2

HPLC traces using fluorescence detection relating to the metabolism studies. (A) Shows the presence of three metabolites M1, M2, and M3 formed from the metabolism of resveratrol (Res) by CYP1B1 microsomes. (B) Shows the metabolism run without the NADPH cofactor. (C) Shows the elution profile of authentic piceatannol (Pic) containing a small amount of resveratrol.

Figure 3

GC–MS studies on the derivatised metabolism sample. (A) Shows the GC–MS elution profile of the derivatised metabolism sample, displayed as a single ion chromatogram at m/z=532. (B) Shows the GC–MS elution profile, displayed as a single ion chromatogram at m/z-532, for derivatised authentic piceatannol (Pic-TMS; m/z=532). (C) Shows the mass spectrum of the metabolism sample peak that eluted at 64 min and 9 s. (D) Shows the mass spectrum of derivatised authentic piceatannol (Pic-TMS).