Synthesis of New Vitamin E Derivatives and Mechanism of the Protection of Oxygen Toxicity in Biological System.

目前已合成了30多种新的生育酚衍生物，对取代苯氧基(PhO^<。用分光光度法测定了这些生育酚在乙醇中对单线态氧（^ 10_2）的猝灭。速率常数k_2和k_Q的对数都与它们的峰值氧化电位E_p相关。淬灭速率k_Q与过氧基（LOO^<）的清除率k_1和k_2呈线性相关。>) （Burton等人报道）和phenoxyl (PhO^<。>)自由基分别被这些生育酚。在天然生育酚中，维生素k_1 -和K_3-对苯二酚及部分雌激素的抗氧化活性分别比-生育酚高数倍，并测定了维生素E自由基与脂质氢过氧化物（LOOH）、维生素C、泛醇和不饱和脂肪酸酯（LH）在溶液中反应的二阶速率常数k_<-1>、K_3、k_4和k_6。通过比较这些速率常数，探讨了生育酚在生物膜和食用油中的抗氧化和促氧化作用机理。

About 30 kinds of new tocopherol derivatives have been synthesized, and the rates of scavenging of substituted phenoxyl radical (PhO^<. >), k_2 and quenching of singlet oxygen ( ^1O_2), k_Q, by these tocopherols have been measured spectrophotometrically in ethanol. Both the log of the rate constants, k_2 and k_Q, were found to correlate with their peak oxidation potential, E_p. The quenching rates, k_Q, were found to be related linearly to the rates k_1 and k_2 of scavenging of peroxyl (LOO^<. >) (reported by Burton et al.) and phenoxyl (PhO^<. >) radicals by these tocopherols, respectively. Vitamin K_1-and K_3- hydroquinone and some estrogens were found to be several times more active than -tocopherol, respectively, which has the highest antioxidant activity among natural tocopherols Further, the second-order rate constants, k_<-1>, k_3, k_4, and k_6 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.