In vitro evaluation of the efficacy of commercial green tea extracts in UV protection

Plants with antioxidant properties are beneficial for preventing the ageing events evoked by UV light, and numerous products based on Camellila sinensis (green tea) are commercially available, many of which claiming to contain bioactive compounds that would prevent UV-induced skin damage. In this study, we tested the efficacy of five commercial green tea extracts used to enrich cosmetic formulations for protecting human and mouse fibroblasts against UV radiation effects and compared with a fluid one prepared according to the Brazilian Pharmacopoeia recommendations. Taking into consideration that the ageing process can be accelerated by solar radiation by excessive free radical generation, leading to depletion of skin antioxidant defences, and its collapse caused by disruption of the metalloproteinase metabolism, we have used their individual (-)-epigallocathechin-3-gallate (EGCG) content, the catalase and SOD status and the matrix-degrading metalloproteases (MMP)-1, MMP-9 and MMP-13 levels as comparative parameters. The EGCG content of the commercial products showed wide variability, ranging from undetectable levels to 58.65 +/- 1.12 mu gmL-1, in contrast with the fluid extract (87.82 +/- 1.35 mu gmL-1). Moreover, only the pharmacopoeic extract was able to significantly reduce MMP degradation while enhancing the levels of SOD and catalase. These results indicate, for the first time, that the methodologies for preparing herbal mixtures can interfere significantly with compounds endowed with photoprotective effects, and the efficacy of products containing C.sinensis extracts thought to act against effects of solar radiation can be compromised.