[Inhibitory effect of green tea extract on promotion and related action of TPA].

Polyphenol components isolated from green tea showed strong antioxidant activity. The green tea extract (GTE) significantly inhibited the promoting effect of TPA in BALB/3T3 cell transformation assays. In in vivo experiments, GTE inhibited edema induced by TPA in mouse ear. The inhibitory effect of GTE on the induction of ornithine decarboxylase activity was also found in mouse skin treated with TPA. GTE decreased the frequency of SCE induced by oxygen radical in IAR 20 liver cells treated with hypoxanthine and xanthine oxidase. Mechanisms of the antipromoting effect of GTE are discussed. Our experimental results suggest that GTE may have some practical use in cancer prevention.