The examination of skin lipid model systems stressed by ultraviolet irradiation in the presence of transition metal ions.

In this study, we investigated the effects of ultraviolet (UV) radiation on lipid peroxidation in the presence of ionised iron as a transition metal. Fatty acids as important intercellular stratum corneum lipids and liposomes were used to model skin lipid systems for our experiments. A UV-A laser and a broad spectrum UV lamp were used to create high-level radiation. UV-related damage was quantified by the thiobarbituric acid assay detecting malondialdehyde. Electrospray mass spectrometry was used to characterise peroxidation products following UV exposure. We have shown that hydro- and endoperoxides are long stable intermediates deriving from lipid peroxidation. The incorporation of unsaturated fatty acids into phospholipid liposomes increased the average liposomal diameter and enhanced sensitivity to UV radiation. By comparing our data from laser induced monochromatic UV-A radiation and broad-spectrum UV irradiation, we have demonstrated that UV-A radiation can also induce lipid peroxidation in lipid model systems.