Cheton P L, Archibald F S
Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada.
Free Radic Biol Med. 1988;5(5-6):325-33. doi: 10.1016/0891-5849(88)90104-9.
In a wide variety of biological systems non-enzyme complexes of the metals copper (Cu) and iron (Fe) have been shown to enhance oxygen radical damage by increasing the production of an oxidative species generally believed to be the hydroxyl free radical (.OH) via "Fenton" and possibly "Haber-Weiss" type reactions. However, the behavior of the chemically and biologically similar transition metal manganese (Mn) with .OH is unknown. Unlike Fe and Cu, inorganic complexes of Mn are known to exist in high concentrations in certain cells. Three different oxygen free radical generating systems and four .OH detection methods were used to investigate the activity of biologically relevant inorganic Mn complexes. These complexes were compared to compounds reported to scavenge and generate .OH. The direct and indirect effects of Mn on the .OH flux were compared by attempting to distinguish the effects of hydrogen peroxide (H2O2), superoxide (O2-), and .OH through the use of selective scavengers and generators. Mn-EDTA and biologically relevant Mn-pyrophosphates and polyphosphates, in contrast to Fe-EDTA, do not generate .OH in these systems. The results suggest that Mn in various forms does, indeed, inhibit oxy-radical damage mediated by .OH, but only if the .OH production is dependent on the presence of O2- or H2O2. Thus, with .OH, as with O2- and H2O2, Mn complexes appear to behave in a fundamentally different fashion from Cu and Fe.
在各种各样的生物系统中，金属铜（Cu）和铁（Fe）的非酶复合物已被证明会通过 “芬顿” 反应以及可能的 “哈伯-维西” 型反应增加一种通常被认为是羟基自由基（·OH）的氧化物种的产生，从而增强氧自由基损伤。然而，化学和生物学性质相似的过渡金属锰（Mn）与·OH的反应行为尚不清楚。与铁和铜不同，已知锰的无机复合物在某些细胞中以高浓度存在。使用三种不同的氧自由基产生系统和四种·OH检测方法来研究具有生物学相关性的无机锰复合物的活性。将这些复合物与据报道能清除和产生·OH的化合物进行比较。通过使用选择性清除剂和产生剂来区分过氧化氢（H2O2）、超氧阴离子（O2-）和·OH的影响，从而比较锰对·OH通量的直接和间接影响。与铁-乙二胺四乙酸（Fe-EDTA）不同，锰-乙二胺四乙酸（Mn-EDTA）以及具有生物学相关性的锰焦磷酸盐和多磷酸盐在这些系统中不会产生·OH。结果表明，各种形式的锰确实会抑制由·OH介导的氧自由基损伤，但前提是·OH的产生依赖于O2-或H2O2的存在。因此，对于·OH，就像对于O2-和H2O2一样，锰复合物的行为似乎与铜和铁有着根本的不同。
