Antioxidant reactions of alpha-tocopherolhydroquinone

alpha-Tocopherolhydroquinone (TQH(2)) is a product of alpha-tocopherol oxidation/reduction that exerts antioxidant effects in biological systems. TQH(2) inhibited autoxidation of methyl linoleate initiated by peroxyl radicals derived from thermolysis of 2,2'-azobis(2,4-dimethylvaleronitrile) in acetonitrile. TQH(2) oxidation yielded alpha-tocopherolquinone (TQ) as a major product and 2,3-epoxy-alpha-tocopherolquinone and 5,6-epoxy-alpha-tocopherolquinone as minor products. Each TQH(2) consumed approximately two peroxyl radicals in the course of the oxidation. The data suggest that TQH(2) scavenges peroxyl radicals primarily by electron transfer to form TQ and secondarily by addition-elimination to form the epoxyquinones.