新しいビタミンE誘導体の合成と生体内における活性酸素消去のメカニズム

概要

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About 50 kinds of new tocopherol derivatives have been synthesized, and the rates of scavenging of substituted phenoxyl radical (PhO ·), k2, and quenching of singlet oxygen (1O2), kQ, by these tocopherols have been measured spectrophotometrically in ethanol. Both the log of the rate constants, k2 and kQ, were found to correlate with their peak oxidation potential, Ep. The quenching rates, kQ, were found to be related linearly to the rates k1 and k2 of scavenging of peroxyl (LOO ·) (reported by Burton et al.) and phenoxyl (PhO ·) radicals by these tocopherols, respectively. Vitamin K1-chromanol and K1-chromenol were found to be 6.9 and 4.5 times more active than α-tocopherol, respectively, which has the highest antioxidant activity among natural tocopherols. Further, the second-order rate constants, k-1, k3, k4, and k6 for the reaction of vitamin E radical with i) lipid hydroperoxides (LOOH), ii) vitamin C, iii) ubiquinol, and iv) unsaturated fatty acid esters (LH), respectively, in solution have been measured. By comparing these rate constants, the mechanism of antioxidant and prooxidant actions of tocopherols in biomembranes and edible oils has been discussed.
日本油化学会の論文