Radical Skin/Sun Protection Factor RSF – Protection against UV-induced Free Radicals in Skin

N atural ageing of the skin is enhanced by environmental factors. Solar UV exposure is one of the main exogenous factors that is participating in that process and that can lead to photoageing, immunosuppression, and photocarcinogenesis. Using a new RSF method to determine UVinduced free radical injuries in the skin, it is possible to quantify the protective effect of sunscreens and UV-filters. The method is based on Electron Spin Resonance (ESR) spectroscopy measurements. Induction of free radicals in skin depends on the wavelength and dose of UV radiation. UVA penetrates into the deeper layers of the skin and induces more ROS as compared with UVB radiation. Therefore, UV filters that absorb or scatter UVA radiation give a stronger protection against free radical damage. In this study different sunscreen formulations have been tested in order to quantify their protection against free radicals. Abstract Both UVA and UVB irradiation are very damaging to the skin. Depending on the wavelength, UV damage occurs via different mechanisms. UVA mainly produces free radicals (FR)/reactive oxygen species (ROS) though interaction with endogenous photosensitizers. These ROS will cause indirect damage to DNA, proteins and membranes. ROS is believed to be involved in photodamage of dermal connective tissue cells and proteins. On the contrary, DNA with its aromatic, heterocyclic bases is a strongly absorbing chromophore for UVB (absorption maximum at 260-265nm). Direct absorption of the UVB photons leads to disruption of DNA, Introduction