Exposure of skin to UV radiation can cause diverse
biological effects, including induction of
inflammation, alteration in cutaneous immune cells and impairment of
contact hypersensitivity (CHS) responses. Our laboratory has demonstrated that oral feeding as well as topical application of a polyphenolic fraction isolated from
green tea (
GTP) affords protection against the carcinogenic effects of UVB (280-320 nm) radiation. In this study, we investigated whether
GTP could protect against UVB-induced immunosuppression and cutaneous inflammatory responses in C3H mice. Immunosuppression was assessed by contact sensitization with 2,4-dinitrofluorobenzene applied to UVB-irradiated skin (local suppression) or to a distant site (systemic suppression), while double skin-fold swelling was used as the measure of UVB-induced
inflammation. Topical application of
GTP (1-6 mg/animal), 30 min prior to or 30 min after exposure to a single dose of UVB (2 kJ/m2) resulted in significant protection against local (25-90%) and systemic suppression (23-95%) of CHS and
inflammation in mouse dorsal skin (70-80%). These protective effects were dependent on the dose of
GTP employed; increasing the dose (1-6 mg/animal) resulted in an increased protective effect (25-93%). The protective effects were also dependent on the dose of UVB (2-32 kJ/m2). Among the four major
epicatechin derivatives present in
GTP, (-)-epigallocatechin-3-gallate, the major constituent in
GTP, was found to be the most effective in affording protection against UVB-caused CHS and inflammatory responses. Our study suggests that
green tea, specifically
polyphenols present therein, may be useful against inflammatory
dermatoses and immunosuppression caused by solar radiation.