OXYBENZONE OXIDATION FOLLOWING SOLAR IRRADIATION OF SKIN - PHOTOPROTECTION VERSUS ANTIOXIDANT INACTIVATION

We used noninvasive Fourier transform (FT) Raman spectroscopy to follo w the fate of the broadly used ultraviolet UVA sun blocker, oxybenzone , after topical application to the skin. Our results showed that oxybe nzone is rapidly photo-oxidized, yielding oxybenzone semiquinone, a po tent electrophile, which reacts with thiol groups on important anti-ox idant enzymes and substrates, such as thioredoxin reductase and reduce d glutathione, respectively. Although oxybenzone is an excellent broad spectrum UVA filter, its rapid oxidation followed by the inactivation of important antioxidant systems indicates that this substance may be rather harmful to the homeostasis of the epidermis, Furthermore, thes e results demonstrate that FT-Raman spectroscopy is a useful method fo r studying the transport and metabolism of active ingredients in topic al preparations.