RESUMO
Resveratrol (RESV), present at concentrations of about 10 microM in red wine, has been found to inhibit events associated with tumor initiation, promotion and progression. The mechanism involved could be the inhibition of activities catalyzed by cytochromes P450 (CYPs), which activate procarcinogens. This led us to investigate the inhibitory effect of RESV on CYP1A, CYP2E1 and CYP3A enzymatic activities and to compare it to that of non volatile compounds present in red wine. Red wine solids (RWS) were prepared by evaporating one volume of red wine to dryness followed by reconstitution with five volumes of buffer (20% natural strength). CYP activities were determined in microsomes from rat liver, human liver or cells containing cDNA-expressed CYPs. Testosterone, chlorzoxazone, and ethoxyresorufin were used as selective substrates for CYP3A, CYP2E1 and CYP1A1/1A2, respectively. RESV and RWS were found to be irreversible (probably mechanism-based) inhibitors for CYP3A4 and non competitive reversible inhibitors for CYP2E1. Their inhibitory potency was assessed using IC(50) values that were found within 4-150 microM for RESV and 0.3-9% natural strength for RWS. Non volatile compounds of other beverages such as white wine, grape juice or Xtra Old Cognac(R) displayed lower inhibitory effect on CYP activities than RWS. When considering the concentration of RESV in red wine (2 microM for 20% natural strength), it appears that RSW inhibitory effect was not only due to RESV, but also to other compounds whose identification would prove to be worthwhile because of their possible chemopreventive properties.