Inhibition of 17alpha-hydroxylase/C17,20-lyase (CYP17) from rat testis by green tea catechins and black tea theaflavins.

In the course of screening for 17alpha-hydroxylase/C17,20-lyase inhibitors from food ingredients, the methanol soluble fraction of green tea and black tea, which were expected to be rich in catechin and theaflavin content, showed potent inhibitory activity. (-)-Epigallocathechin gallate and theaflavin 3-O-gallate with a pirogallol moiety significantly inhibited C17,20-lyase activity on IC50 values of 24.5 microM and 11.5 microM respectively. They had potent cytotoxicity against human prostate cancer LNCaP cells (IC50=28.1 microM and 37.4 microM).