Efficacy of sunscreens containing pre-tocopheryl in a surviving human skin model submitted to UVA and B radiation.

The aim of the present study was to evaluate by means of histological and biochemical tools the additive efficacy of pre-tocopheryl during photoprotection using a sunscreen containing mineral sunblock agents 50B-10A (TiO(2), ZnO) and pre-tocopheryl in comparison to a cream containing only mineral sunblock agents 50B-10A. For this purpose, an ex vivo technique and an acetone-impaired human skin model were used in order to approximate in vivo metabolic conditions. Creams were topically applied to the surface of the epidermis and submitted to UV radiations. Then, human skin explants were maintained alive in organ culture for 3 days. Free radical modulation was analysed by hydroperoxide assay. Epidermal (involucrin, cell proliferation, stratum corneum lipids) and dermal changes (elastic fibres and collagen) were studied. Analysis of ex vivo surviving skin samples impaired by UV irradiations and treated with the mineral sunscreen 50B-10A showed a significant decrease in hydroperoxide production and an improvement in the elastic fibre and collagen network in the dermis. Adding pre-tocopheryl to this formula induced an increase in involucrin and epidermal lipids such as squalenes and ceramides. Altogether, these results confirm the efficacy of the combination of a mineral sunscreen and pre-tocopheryl in photoprotection and free radical protection.