Detection of Ethylene for in Viro Evaluation of the Uv Photoprotection

In this study, the antioxidant capacity during UV exposure has been investigated by using a laser-based trace gas detector for the detection of gaseous ethylene as an indicator for lipid peroxidation. Biocream was used as a control and ascorbic acid, butylated hydroxytoluene, phloroglucinol and hydroquinone were added as antioxidants in a mixing concentration of 2.5% (w/w). The experimental results show that there is a decrease in the number of ROS due to the presence of antioxidants, from which ascorbic acid is the most effective. The detection method offers a direct and on-line way to evaluate the capability of antioxidant in reducing the harmful effect of the UV radiation. INTRODUCTION: In the past various in vitro and in vivo methods have been presented to evaluate the photo protection efficacy of sunscreen based on the measurement of sun protection factor (SPF), UVA/UVB ratio, and their critical wavelength 1, 2, 3, 4, . The determination of SPF in vivo is time consuming and expensive; in addition, the method is more suitable for testing the effect of UVB radiation due to its exclusion of UVA radiation 4, . For testing the efficacy of sunscreen against UVA various in vitro and in vivo methods have been proposed, such as spectrophotometric based methods measuring the UVA absorption of sunscreens 2, . However, in the latter method the photochemical reaction within the sample as a result of UVA exposure is not considered. Other research show that during the exposure of UVA on the skin, various reactive oxygen species (ROS) are generated; such as the presence of ROS using ESR (Electron Spin Resonance) 7, . UVA radiation stimulates the generation of ROS, which itself induces lipid peroxidation in skin tissue. By investigating the end products of lipid peroxidation the presence of ROS can also be justified. In the past lipid peroxidation was investigated using the well known TBARS (ThioBarbituric Acid Reactive Substances) method 9, , measuring malondialdehyde (MDA) from homogenized samples to prove the occurrence of lipid peroxidation. It is known that the lipid peroxidation process produces various gases such as ethylene and ethane . As gaseous product of lipid peroxidation during UV illumination on the skin ethylene has been investigated before, using a laserbased detection method 11, 12, 13, . Monitoring the end product of lipid peroxidation via gas emissions provides an alternative and powerful method, due to its on-line and non invasive capabilities. In this study, we will use the same laser-based photoacoustic detection method for the evaluation of the protection ability of antioxidant for UV radiation. This protection capability of antioxidant is tested by measuring gaseous ethylene released during UV irradiation as an indicator for the lipid peroxidation process.