title: Addition products of alpha-tocopherol with lipid-derived free radicals.
abstract: The addition products of alpha-tocopherol with lipid-derived free radicals have been reviewed. Free radical scavenging reactions of alpha-tocopherol take place via the alpha-tocopheroxyl radical as an intermediate. If a suitable free radical is present, an addition product can be formed from the coupling of the free radical with the alpha-tocopheroxyl radical. The addition products of alpha-tocopherol with lipid-peroxyl radicals are 8a-(lipid-dioxy)-alpha-tocopherones, which are hydrolyzed to alpha-tocopherylquinone. On the other hand, the carbon-centered radicals of lipids prefer to react with the phenoxyl radical of alpha-tocopherol to form 6-O-lipid-alpha-tocopherol under anaerobic conditions. The addition products of alpha-tocopherol with peroxyl radicals (epoxylinoleoyl-peroxyl radicals) produced from cholesteryl ester and phosphatidylcholine were detected in the peroxidized human plasma using a high-sensitive HPLC procedure with postcolumn reduction and electrochemical detection. Thus, the formation of these addition products provides us with much information on the antioxidant function of vitamin E in biological systems.
authors.affiliation: Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu City, Gifu 501-1193, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamauchi
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000378:metabolism; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism; D024502:alpha-Tocopherol / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D008055:Lipids; D017382:Reactive Oxygen Species; D024502:alpha-Tocopherol