Mechanism of Lipid Radical Formation Following Exposure of Epidermal Homogenate to Ultraviolet Light

• Published in: Journal of investigative dermatology Vol. 97; no. 6; pp. 1044 - 1047
• Main Authors: Ogura, Ryohei, Sugiyama, Masayasu, Nishi, Juichi, Haramaki, Nobuya
• Format: Journal Article
• Language: English
• Published: Danvers, MA Elsevier Inc 01-12-1991; Nature Publishing
• Subjects: Animals; Biological and medical sciences; Electron Spin Resonance Spectroscopy; Epidermis - radiation effects; Free Radicals; Fundamental and applied biological sciences. Psychology; Iron Chelating Agents - pharmacology; Lipid Peroxides - metabolism; Rats; Tissues, organs and organisms biophysics; Ultraviolet Rays; Xanthine Oxidase - pharmacology; Ultraviolet irradiation; Organic free radical; Animal; Epidermis; Lipids; Biosynthesis; Skin; Biological effect; Metabolism; In vitro
• ISSN: 0022-202X; 1523-1747
• DOI: 10.1111/1523-1747.ep12492553

It has been suggested that oxygen free radicals are important mediators of lipid peroxidation in the epidermis exposed to ultraviolet (UV) light. However, it is not clear whether it is the superoxide anion radical (O2-) or the hydroxyl radial (.OH) that plays the major role in producing the lipid radical (L.) following UV exposure. In this study, we used electron spin resonance (ESR) technique with the spin trap (5,5-dimethyl-1-pyrroline-N-oxide [DMPO]) to determine which active oxygen species is involved in the UV -induced lipid radical formation (DMPO-L.: aN = 15.5 G, aH = 22.7 G). In the presence of superoxide dismutase or the metal-chelating agent, the DMPO-spin adduct spectrum of lipid radicals was reduced remarkably. The lipid radicals were formed by the hydroxyl radical generation system, not the superoxide anion generation system. The hydroxyl radical was found to be the direct active oxygen species that can generate lipid radicals as a result of .OH-mediated hydrogen atom abstraction. Superoixde anion radical stimulated the generation of hydroxyl radical via the iron-catalyzed reaction.