Leung H W, Vang M J, Mavis R D
Biochim Biophys Acta. 1981 May 22;664(2):266-72. doi: 10.1016/0005-2760(81)90049-7.
The time course of peroxidation of rat liver microsomes by FeSO4 in the presence of ascorbate showed a delay in the onset of peroxidation compared to the time course when NADPH replaced ascorbate as the electron donor. The delay was consistent with an antioxidant function of ascorbate, possibly mediated through endogenous vitamin E. In order to further investigate the cooperation between ascorbate and vitamin E in suppressing lipid peroxidation, a liposomal system containing polyunsaturated phospholipids was used. Peroxidation was initiated by ferrous iron at pH 5, where spontaneous oxidation of Fe2+ did not occur and the antioxidant properties of ascorbic acid could be characterized independently of its pro-oxidant properties as a reducer of Fe3+. Ascorbic acid alone at concentrations of 30--100 microM delayed peroxidation by 20 min and at higher concentrations prevented peroxidation for 60 min. Physiological levels of vitamin E decreased peroxidation at early time points but the vitamin was apparently consumed during the course of the incubation. The presence of both vitamin C and vitamin E produced suppression of peroxidation at early time points (0--20 min) which was approximately the sum of the individual inhibitions. At longer time points, however, the mixture of antioxidants was much more effective than the sum of both vitamins alone. This suggests that interaction between these antioxidants yields and enhanced delivery of antioxidant protection.
在抗坏血酸存在的情况下，硫酸亚铁对大鼠肝微粒体的过氧化作用时间进程显示，与以NADPH替代抗坏血酸作为电子供体时的时间进程相比，过氧化作用的起始出现延迟。这种延迟与抗坏血酸的抗氧化功能一致，可能是通过内源性维生素E介导的。为了进一步研究抗坏血酸和维生素E在抑制脂质过氧化中的协同作用，使用了含有多不饱和磷脂的脂质体系统。过氧化作用由pH 5的亚铁离子引发，在此条件下Fe2+不会发生自发氧化，并且可以独立于抗坏血酸作为Fe3+还原剂的促氧化特性来表征其抗氧化特性。单独使用浓度为30 - 100 microM的抗坏血酸可使过氧化作用延迟20分钟，而在更高浓度下可防止过氧化作用60分钟。生理水平的维生素E在早期时间点可降低过氧化作用，但在孵育过程中该维生素显然被消耗。维生素C和维生素E同时存在时，在早期时间点（0 - 20分钟）可抑制过氧化作用，其抑制程度约为各自单独抑制作用之和。然而，在更长时间点，抗氧化剂混合物比单独两种维生素的作用之和更有效。这表明这些抗氧化剂之间的相互作用产生并增强了抗氧化保护作用。
