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Scientific studies related to EGCG(2)
Studies in animal models suggest that antioxidant and anti-inflammatory polyphenols in green tea extracts may reduce some of the harmful effects following exposure to UV radiation (Katiyar et al., 1995). Elmets and coworkers (2000) applied extracts of green tea polyphenols (GTP) or purified catechins (EGCG, EGC, EGC or EC) onto the skin of healthy volunteers. The treated sites were then exposed to a dose of simulated solar radiation at two times the minimum level that was required to produce erythema in untreated skin (2 minimal erythema dose or 2 MED). The UV-treated tissues were examined for erythema, UV-induced DNA damage, reduction in UV-sensitive Langerhans cells, and the presence of sunburn cells. Pretreatment of the skin with a 5% solution of GTP dramatically reduced the UV-induced erythema response (>80% reduction), reduced the number of sunburned cells (66% reduction), increased the survival of Langerhans cells (58% reconstitution of population), and reduced the UV-induced DNA damage (45% reduction). The only purified green tea polyphenols that were able to exert a similar UV-protective effect were EGCG and ECG, the catechins that possess gallate ester moieties. The spectrophotometric profile of EGCG and other green tea polyphenolics indicated that they do not absorb UVB and therefore, the UV-protective effects are not due to sunscreen-like effects.