Green tea polyphenolic antioxidants and skin photoprotection (Review)

Green tea is consumed as a popular beverage worldwide particularly in Asian countries like China, Korea, Japan and India. It contains polyphenolic com pounds also known as epicatechins, which are antioxidant in nature. Many la boratories have shown that topical treatment or oral consumption of green t ea polyphenols inhibits chemical carcinogen- or ultraviolet radiation-induc ed skin tumorigenesis in different animal models. Studies have shown that g reen tea extract also possesses anti-inflammatory activity. These anti-infl ammatory and anti-carcinogenic properties of green tea are due to their pol yphenolic constituents present therein. The major and most chemopreventive constituent in green tea responsible for these biochemical or pharmacologic al effects is (-)-epigallocatechin-3-gallate (EGCG). Understanding the mole cular mechanisms of these effects of green tea is a subject of investigatio n in many laboratories. Treatment of green tea polyphenols to skin has been shown to modulate the biochemical pathways involved in inflammatory respon ses, cell proliferation and responses of chemical tumor promoters as well a s ultraviolet (UV) light-induced inflammatory markers of skin inflammation. Topical treatment with EGCG on mouse skin also results in prevention of UV B-induced immunosuppression, and oxidative stress. The protective effects o f green tea treatment on human skin either topically or consumed orally aga inst UV light-induced inflammatory or carcinogenic responses are not well u nderstood. Based on documented extensive beneficial effects of green tea on mouse skin models and very little in human skin, many pharmaceutical and c osmetic companies are supplementing their sk:in care products with green te a extracts. Therefore, the focus of this communication is to review and ana lyze the photoprotective effects of green tea polyphenols to skin.