Research Center for Advanced Science and Technology, The University of Tokyo, Komaba, Tokyo, 153-8904, Japan.
Free Radic Biol Med. 2021 Nov 20;176:1-15. doi: 10.1016/j.freeradbiomed.2021.09.001. Epub 2021 Sep 3.
Lipids are oxidized in vivo by multiple oxidizing species with different properties, some by regulated manner to produce physiological mediators, while others by random mechanisms to give detrimental products. Vitamin E plays an important role as a physiologically essential antioxidant to inhibit unregulated lipid peroxidation by scavenging lipid peroxyl radicals to break chain propagation independent of the type of free radicals which induce chain initiation. Kinetic data suggest that vitamin E does not act as an efficient scavenger of nitrogen dioxide radical, carbonate anion radical, and hypochlorite. The analysis of regio- and stereo-isomer distribution of the lipid oxidation products shows that, apart from lipid oxidation by CYP enzymes, the free radical-mediated lipid peroxidation is the major pathway of lipid oxidation taking place in humans. Compared with healthy subjects, the levels of racemic and trans,trans-hydro (pero)xyoctadecadienoates, specific biomarker of free radical lipid oxidation, are elevated in the plasma of patients including atherosclerosis and non-alcoholic fatty liver diseases. α-Tocopherol acts as a major antioxidant, while γ-tocopherol scavenges nitrogen dioxide radical, which induces lipid peroxidation, nitration of aromatic compounds and unsaturated fatty acids, and isomerization of cis-fatty acids to trans-fatty acids. It is essential to appreciate that the antioxidant effects of vitamin E depend on the nature of both oxidants and substrates being oxidized. Vitamin E, together with other antioxidants such as vitamin C, contributes to the inhibition of detrimental oxidation of biological molecules and thereby to the maintenance of human health and prevention of diseases.
脂质在体内可被多种具有不同性质的氧化物质氧化，其中一些通过调节机制产生生理介质，而另一些则通过随机机制产生有害产物。维生素 E 作为一种生理必需的抗氧化剂，通过清除脂质过氧自由基来抑制不受调节的脂质过氧化，从而打破链的传播，而与引发链起始的自由基的类型无关，发挥着重要作用。动力学数据表明，维生素 E 不能作为二氧化氮自由基、碳酸盐阴离子自由基和次氯酸盐的有效清除剂。脂质氧化产物的区域和立体异构体分布分析表明，除 CYP 酶介导的脂质氧化外，自由基介导的脂质过氧化是人类脂质氧化的主要途径。与健康受试者相比，包括动脉粥样硬化和非酒精性脂肪肝疾病患者的血浆中，自由基介导的脂质氧化的特异性生物标志物——旋光和反式、顺式-羟（过）氧基十八碳二烯酸的外消旋和反式异构体的水平升高。α-生育酚作为主要的抗氧化剂，而γ-生育酚可清除诱导脂质过氧化、芳香族化合物和不饱和脂肪酸硝化以及顺式脂肪酸向反式脂肪酸异构化的二氧化氮自由基。必须认识到，维生素 E 的抗氧化作用取决于氧化剂和被氧化底物的性质。维生素 E 与维生素 C 等其他抗氧化剂一起，有助于抑制生物分子的有害氧化，从而维持人体健康和预防疾病。
