In vivo evaluation of black and green tea dermal products against UV radiation.

Aqueous extracts of black and green tea (Camellia sinensis) were obtained by freeze-drying for this study. The extracts were evaluated based on tea quality control tests, UV, IR scans, and in vitro antioxidant capacity tests. Dermal products from the tea extracts were designed and manufactured. Black and green tea gels were tested in vivo in the forearms of six subjects using an artifical UV (200-400 nm) source. The tested formulations were green tea gel, black tea gel, 0.3% caffeine gel, carbomer gel base, and a control. Depending on tea quality, the samples resulted in water soluble fractions of 24.5-39.5%. UV and IR scans specifically showed peaks for alkaloids like caffeine, catechins such as epigallocatechin gallate, and polyphenols with dimeric and polymeric structures such as theaflavins (TFs) and thearubigins (TRs). Antioxidant and free radical scavenging activities of black and green tea samples were found to be high and comparable; activity levels for black tea, green tea, high quality black tea, and L-ascorbic acid were 0.48, 0.50, 0.82, and 1.32 mM TR/mg, respectively. No UV-induced erythema was observed at the black and green tea gel sites in any of the subjects. UV-induced erythema was consistently present in various grades at caffeine gel, carbomer gel, and control sites. Results led to the conclusion that freeze-dried black and green tea extracts had strong UV absorbance. Formulating those extracts into dermal gels protected the skin against UV-induced erythema. Therefore, tea extracts were found to be promising candidates for their ability to protect against the harmful effects of UV radiation, such as erythema and premature aging of the skin.