Efficacy of Sunscreens Containing Pre-Tocopheryl in a Surviving Human Skin Model Submitted to UVA and B Radiation

Abstract

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 (TiO₂, 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.

Inhibition of nitric oxide and reactive oxygen species production improves the ability of a sunscreen to protect from sunburn, immunosuppression and photocarcinogenesis

“…In contrast, the study of Bissett and McBride 27 irradiated with approximately equal amounts of UVB and UVA. Supplementation of a sunscreen with the ROS scavenger vitamin E has been shown to improve the ability of a sunscreen to protect the dermal elastic fibre and collagen network of cultured human skin from photodamage 28 . A combination of vitamins E and C improves sunscreen protection from sunburn cell formation in swine skin 29…”

Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

“…TiO 2 nanoparticles exert protective effects on UV irradiated skin models [54][55][56] , and one study reports that CeO 2 nanoparticles protect cells from the toxic effects of UV rays 25 To analyse the mechanisms through which CeO 2 nanoparticles exert their cytoprotective effect, we shifted to cells physiologically growing in suspension (i.e., blood cells instead of trypsinized keratinocytes) because some of the end-points (e.g., mutagenesis or cell cycle analyses) require long incubation times that would inevitably require re-adhesion of the trypsinized cells, i.e., a poorly controllable condition. Our system of choice was thus Jurkat human T lymphocytes, because these cells have been thoroughly studied in 33 57,58 .…”

Ex vivo study of the home-use TriPollar RF device using an experimental human skin model

“…The ex vivo method presented in the current study to obtain premature aging of human skin samples in order to investigate the reparative effects of various anti-aging agents has previously been reported (8)(9)(10). It allows quantitative analysis of the effects of anti-aging agents and devices on the fibrous components of the dermis in conditions which reproduce those of human skin in vivo.…”

“…One part was left as the control while the other two parts were immediately subjected to a UV aging process accomplished by exposure to UVA (365 nm) at a fluence of 12 J/cm 2 together with UVB (312 nm) at 2 J/cm 2 from a UV radiation source (Vilbert-Lourmat, France). Such UV exposure has previously been shown to induce premature structural and cellular skin photoaging effects on fibroblasts and dermal collagen in human skin explants (8)(9)(10).…”