Green tea polyphenol treatment to human skin prevents formation of ultraviolet light B-induced pyrimidine dimers in DNA

Cancer chemopreventive effects of polyphenols from green tea (GTP) in mouse models of photocarcinogenesis are established. The present study is extend ed from mouse model to human system in vivo to determine the effect of topi cal application of GTP to human individuals against UTI light-induced DNA d amage in the form of eyclobutane pyrimidine dimers (CPDs) in the skin. UVB- induced CPDs were detected by immunohistochemical technique using monoclona l antibodies to thymine diners, With the gradual increase in UVB dose, both erythema response and CPD formation in the skin was increased. GTP treatme nt inhibited both WE-induced erythema response as well as CPD formation, To pical treatment with GTP (similar to 1 mg/cm(2) of skin area) 20 min before human buttock skin (sun-protected site) exposure to UVB inhibited CPD form ation in epidermis by 81, 70, 60, and 60% at 0.5, 1.0, 2.0, and 4.0 minimal erythema dose of UV exposure, respectively. Treatment of human skin with v arying doses of GTP (1-4 mg/2.5 cm(2) of skin area) before a single dose of UVB exposure (4.0 minimal erythema close) decreased dose dependently the f ormation of WE-induced CPDs in both epidermis and dermis, The inhibition of UVB-induced CPDs by GTP treatment may be, at least in part, responsible fo r the inhibition of photocarcinogenesis, Our data suggest that GTP may be u sed as a novel chemopreventive candidate and possible strategy to reduce UV -induced skin cancer risk in the human population.