Protection against ultraviolet B radiation-induced photocarcinogenesis in hairless mice by green tea polyphenols.

Our recent studies have shown that polyphenols present in green tea (GTP) possess significant antigenotoxic activity and afford protection against polycyclic aromatic hydrocarbon-induced skin tumor initiation in mice. In this study we assessed the effect of oral feeding and topical application of GTP on ultraviolet B (UVB) radiation-induced skin carcinogenesis in female SKH-1 hairless mice. Chronic oral feeding of GTP (0.1%, w/v) in drinking water resulted in significantly (P less than 0.01) lower tumor yield (percent of animals with tumors and number of tumors per mouse) and extended TDT50 (P less than 0.05), as compared to animals receiving normal drinking water. Topical application of GTP before UVB irradiation also afforded protection against photocarcinogenesis; however, the protective response was lower than that observed by oral feeding of GTP in drinking water. These results, in conjunction with our prior publications, suggest that consumption of green tea may reduce the risk of some forms of human cancer induced by both physical and chemical environmental carcinogens.