Longoni B, Salgo M G, Pryor W A, Marchiafava P L
Dipartimento di Fisiologia e Biochimica, Universita' di Pisa, Italy.
Life Sci. 1998;62(10):853-9. doi: 10.1016/s0024-3205(98)00002-2.
We here report the activity of the neurohormone melatonin (MLT) as a scavenger of free radicals in two different experimental models: (a) linoleic acid peroxidation initiated by different free radical-generating systems and (b) a multilamellar vesicle system composed of dilinoleoylphosphatidylcholine. In system (a) linoleic acid peroxidation, induced by either the water-soluble initiator 2,2'-azobis (2-amidinopropane) dihydrochloride (ABAP) or Fe2+-EDTA addition to 2.6 mM linoleic acid dispersed in SDS-phosphate buffer, was evaluated as the formation of conjugated dienes, measured spectrophotometrically at 236 nm. MLT did not reduce the rate of peroxidation induced by ABAP, but did reduce, in a concentration-dependent fashion, the rate of the reaction activated by Fe2+-EDTA. In system (b) multilamellar vesicles were used as the substrate for lipid peroxidation, initiated by Fe2+-EDTA and determined by means of malonaldehyde (MDA) and 4-hydroxyalkenal (4-HDA) content. MLT was found to be slightly more effective in system (b) than in the dispersed linoleic acid system (see a). These results show that MLT inhibits lipid damage induced by oxygen free radicals. However, MLT is only about one one-hundredth as effective an antioxidant as vitamin E in the micelles system.
我们在此报告神经激素褪黑素（MLT）在两种不同实验模型中作为自由基清除剂的活性：（a）由不同自由基生成系统引发的亚油酸过氧化反应，以及（b）由二亚油酰磷脂酰胆碱组成的多层囊泡系统。在系统（a）的亚油酸过氧化反应中，通过水溶性引发剂2,2'-偶氮双（2-脒基丙烷）二盐酸盐（ABAP）或向分散于SDS-磷酸盐缓冲液中的2.6 mM亚油酸中添加Fe2+-EDTA来引发反应，以在236 nm处通过分光光度法测定共轭二烯的形成来评估过氧化反应。MLT并未降低由ABAP引发的过氧化反应速率，但确实以浓度依赖的方式降低了由Fe2+-EDTA激活的反应速率。在系统（b）中，多层囊泡被用作脂质过氧化反应的底物，该反应由Fe2+-EDTA引发，并通过丙二醛（MDA）和4-羟基烯醛（4-HDA）含量来测定。发现MLT在系统（b）中的效果比在分散的亚油酸系统中略好（见a）。这些结果表明，MLT可抑制氧自由基诱导的脂质损伤。然而，在胶束系统中，MLT作为抗氧化剂的效果仅约为维生素E的百分之一。
