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PROTECTION AGAINST ULTRAVIOLET B RADIATION‐INDUCED EFFECTS IN THE SKIN OF SKH‐1 HAIRLESS MICE BY A POLYPHENOLIC FRACTION ISOLATED FROM GREEN TEA
Author(s) -
Agarwal Rajesh,
Katiyar Santosh K.,
Khan Sikandar G.,
Mukhtar Hasan
Publication year - 1993
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1993.tb04954.x
Subject(s) - hairless , chemistry , polyphenol , pharmacology , antioxidant , gtp' , epidermis (zoology) , tumor promotion , ornithine decarboxylase , human skin , carcinogenesis , biochemistry , biology , enzyme , genetics , anatomy , gene
In prior studies we and others have shown that oral feeding of a polyphenolic fraction isolated from green tea (GTP) or water extract of green tea affords protection against ultraviolet B (UVB) radiation‐induced carcinogenesis in SKH‐1 hairless mice (Wang et al., Carcinogenesis 12, 1527–1530, 1991). It is known that exposure of murine skin to UVB radiation results in cutaneous edema, depletion of the antioxidant‐defense system and induction of ornithine decarboxylase (ODC) and cyclooxygenase activities. In this study we assessed the protective effect of GTP on these UVB radiation‐caused changes in murine skin. Oral feeding of 0.2% GTP (wt/vol) as the sole source of drinking water for 30 days to SKH‐1 hairless mice followed by irradiation with UVB (900 mJ/cm 2 ) resulted in significant protection against UVB radiation‐caused cutaneous edema ( P <0.0005) and depletion of the antioxidant‐defense system in epidermis ( P <0.01–0.02). The oral feeding of GTP also resulted in significant protection against UVB radiation‐caused induction of epidermal ODC ( P <0.005–0.01) and cyclooxygenase activities ( P <0.0001) in a time‐dependent manner. Our data indicate that the inhibition of UVB radiation‐caused changes in these markers of tumor promotion in murine skin by GTP may be one of the possible mechanisms of chemopreventive effects associated with green tea against UVB‐induced tumorigenesis. The results of this study suggest that green tea, specifically polyphenols present therein, may be useful against inflammatory responses associated with the exposure of skin to solar radiation.