Effect of metabolic inhibition against CYP3A4 by catechins in bottled green tea drinks

Catechins, major polyphenol constituents of green tea, are well known because of their antioxidant activity and chemopreventive effects against cancers. We determined catechins (catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG) and gallocatechin gallate (GCG)) in bottled green tea drinks. The effects of temperature on the conversion of EGCG to GCG by a heat treatment were examined. The epimerization reaction seemed to proceed slowly around 80°C, and was observed to occur rapidly at 98°C. In this study, we also investigated the effect of metabolic inhibition against CYP3A4 by individual catechins. The inhibition effects of the gallate catechins were greater than those of non-gallate catechins.