Yamamoto K, Niki E
Department of Reaction Chemistry, Faculty of Engineering, University of Tokyo, Japan.
Biochim Biophys Acta. 1988 Jan 19;958(1):19-23. doi: 10.1016/0005-2760(88)90241-x.
The dual functions of alpha-tocopherol in the oxidation of lipids in aqueous dispersions in the presence of iron were studied, aiming specifically at elucidating the effect of interaction between alpha-tocopherol and iron. Ferrous ion decomposed hydroperoxide rapidly and induced the free radical chain oxidation of soybean phosphatidylcholine liposomes. alpha-Tocopherol acted primarily as a radical scavenger in the oxidation induced by ferrous ion and acted as an antioxidant. Ferric ion decomposed hydroperoxide much more slowly than ferrous ion, but it also induced the oxidation of liposomal membranes. alpha-Tocopherol incorporated into artificial liposomal membranes reduced ferric ion rapidly to give more reactive ferrous ion, and alpha-tocopherol acted either as an antioxidant or as a prooxidant depending on the experimental conditions. When alpha-tocopherol was depleted by the interaction with ferric ion, it acted solely as a prooxidant, whereas if some alpha-tocopherol remained, it acted as an antioxidant. On the other hand, alpha-tocopherol residing in the intact erythrocyte membranes did not reduce ferric ion in the aqueous region.
研究了在铁存在的情况下，α-生育酚在水分散体中脂质氧化过程中的双重作用，特别旨在阐明α-生育酚与铁之间相互作用的影响。亚铁离子能迅速分解氢过氧化物，并引发大豆磷脂酰胆碱脂质体的自由基链式氧化反应。在亚铁离子引发的氧化反应中，α-生育酚主要作为自由基清除剂，起到抗氧化剂的作用。铁离子分解氢过氧化物的速度比亚铁离子慢得多，但它也能引发脂质体膜的氧化。掺入人工脂质体膜中的α-生育酚能迅速将铁离子还原为活性更高的亚铁离子，并且根据实验条件，α-生育酚既可以作为抗氧化剂，也可以作为促氧化剂。当α-生育酚因与铁离子相互作用而耗尽时，它仅作为促氧化剂起作用，而如果仍有一些α-生育酚存在，它则作为抗氧化剂起作用。另一方面，存在于完整红细胞膜中的α-生育酚不会还原水相区域中的铁离子。
