The mechanistic study of the interaction between α-tocopherol and biological oxidative radicals

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α-Tocopherol (α-Toc) is a ubiquitous antioxidant in biological systems and protects biological molecules from the oxidation induced by various kinds of active oxygens. Nitric oxide (NO), which is a biological oxidative radical, has been known to fill the roles of mediators in many physiological phenomena. In addition, NO and its oxygenated derivatives bring about cytotoxicity when they are generated in relatively high concentration.Since these active species derived from NO are supposed to give oxidative damages to the body, it is important to investigate their interaction with α-Toc. In this study, the reactions of NO with α-Toc was carried out using limited amounts of NO and molecular oxygen in order to reveal a reactivity and a productive interaction between them. Since vitamin E exists in lipid part of the biological system, these reactions were carried out in various organic solvents. The high yields of five major products, αptocquinone (α-TQ) (max21%), tocored (max52%), 5-formyl-7, 8-dimethyltocol (5-FDT) (max29%), 2, 3-dihydro-7a-(3-hydroxy-3,7,11,15-tetramethyl-6, 10, 14-hexadecatrienyl)-3, 5, 6, 9, 10, 11a-hexamethyl-3(4, 8, 12-trimethyl-3, 7, 11-tridecatrienyl)-1H-pyrano[2,3a]xanthene-8(7a-H), 11(11a-H)-dione(Toc-dimer) (max10%), 2-(3-hydroxy-3, 7, 11, 15-tetramethylhexadecyl)-5, 6-dimethyl-3-nitrosoxymethyl-[1, 4] benzoquinone (3-Nitrite), were obtained from the reaction of α-Toc. These were analyzed by the gradient elution method with the high performance liquid chromatograhy.