Reactions of Peroxynitrite with γ-Tocopherol

The reaction of peroxynitrite with γ-tocopherol (γ-TH) in a methanol/potassium phosphate buffer solution results in the formation of four major products, which were identified as 2,7,8-trimethyl-2-(4,8,12-trimethyldecyl)-5-nitro-6-chromanol (NGT), 2,7,8-trimethyl-2-(4,8,12-trimethyldecyl)-5,6-chromaquinone (tocored), and two diastereomers of 8a-(hydroxy)-γ-tocopherone. NGT was the major product formed in these reactions, and its formation was modestly increased by increasing amounts of Fe3+−EDTA. Tocored and NGT also were formed when γ-TH was exposed to 3-morpholinosydnonimine (SIN-1), a compound that decomposes to form peroxynitrite. When γ-TH reacted with the nitrating agent NO2+BF4- in acetonitrile or methanol/potassium phosphate buffer, NGT and tocored also were formed, but the major product detected was γ-tocopherol quinone (γ-TQ). This product was not detected in reactions involving peroxynitrite. Oxidation of γ-TH by peroxynitrite involves nitration and electron transfer reactions. Since the produc...