Hogg N, Darley-Usmar V M, Wilson M T, Moncada S
Department of Chemistry and Biological Chemistry, University of Essex, U.K.
Biochem J. 1992 Jan 15;281 ( Pt 2)(Pt 2):419-24. doi: 10.1042/bj2810419.
Both nitric oxide (NO) and superoxide are generated by macrophages, neutrophils and endothelial cells. It has been postulated that the generation of these two radicals under physiological conditions can lead to the formation of peroxynitrite and (as a result of the homolytic lysis of this molecule) the production of hydroxyl radicals. We have used 3-morpholinosydnonimine N-ethylcarbamide (SIN-1), a sydnonimine capable of generating both NO and superoxide simultaneously, to test this hypothesis. SIN-1 (1 mM) generated superoxide and NO at rates of 7.02 microM/min and 3.68 microM/min respectively in phosphate-buffered saline, pH 7.2, at 37 degrees C. Incubation of SIN-1 with both deoxyribose and sodium benzoate resulted in the formation of malondialdehyde (MDA). In addition, the incubation of SIN-1 with sodium benzoate resulted in the production of compounds with fluorescence emission spectra characteristic of hydroxylated products. Both the production of MDA and the generation of fluorescent compounds were inhibited by the hydroxyl radical scavenger mannitol. In all the above respects, SIN-1 mimicked the production of hydroxyl radicals from the ascorbate-driven Fenton reaction. Catalase had no effect on the SIN-1-dependent generation of MDA, and superoxide dismutase was partially inhibitory. SIN-1 produces an oxidant with the properties of the hydroxyl radical by a mechanism clearly different to that of the Fenton reaction. We conclude that the simultaneous production of NO and superoxide from SIN-1 results in the formation of hydroxyl radicals.
一氧化氮（NO）和超氧化物均由巨噬细胞、中性粒细胞和内皮细胞产生。据推测，在生理条件下这两种自由基的产生可导致过氧亚硝酸盐的形成，以及（由于该分子的均裂裂解）羟基自由基的产生。我们使用了3-吗啉代西多硝胺N-乙基甲酰胺（SIN-1），一种能够同时产生NO和超氧化物的西多硝胺，来验证这一假设。在37℃、pH 7.2的磷酸盐缓冲盐水中，SIN-1（1 mM）分别以7.02 μM/分钟和3.68 μM/分钟的速率产生超氧化物和NO。将SIN-1与脱氧核糖和苯甲酸钠一起孵育会导致丙二醛（MDA）的形成。此外，将SIN-1与苯甲酸钠孵育会产生具有羟基化产物荧光发射光谱特征的化合物。MDA的产生和荧光化合物的生成均受到羟基自由基清除剂甘露醇的抑制。在上述所有方面，SIN-1模拟了抗坏血酸驱动的芬顿反应中羟基自由基的产生。过氧化氢酶对SIN-1依赖性MDA的产生没有影响，超氧化物歧化酶有部分抑制作用。SIN-1通过一种明显不同于芬顿反应的机制产生具有羟基自由基性质的氧化剂。我们得出结论，SIN-1同时产生NO和超氧化物会导致羟基自由基的形成。
