Douki T, Cadet J
CEA/Département de Recherche Fondamentale sur la Matère Condensée, SCiB/LAN, Grenoble, France.
Free Radic Res. 1996 May;24(5):369-80. doi: 10.3109/10715769609088035.
Reaction of nitric oxide with superoxide anion produces the highly reactive species peroxynitrite (ONOO-). This compound has been shown to be a strong oxidant of lipids and proteins. However, no data are available on its effect on DNA, with the exception of the induction of strand breaks. We report the result of studies on the reactions of peroxynitrite with the adenine and guanine moieties of nucleosides and isolated DNA. The samples were analyzed for 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo),2,2-diamino-4-[(2-deoxy-beta-D-erythro-pentofuranosyl) amino]-5-(2H)-oxazolone (oxazolone) and 8-oxo-7,8-dihydro-2'-deoxyadenosine (8-oxo-dAdo). The effects of peroxynitrite treatment were compared with those of ionizing radiation in aerated aqueous solution, chosen as a source of hydroxyl radicals. At the nucleoside level, both oxidizing conditions led to the formation of oxazolone and 8-oxo-dAdo. In addition, evidence was provided for the formation of the 4R* and 4S* diastereoisomers of 4-hydroxy-8-oxo-4, 8-dihydro-2'-deoxyguanosine. The latter dGuo oxidation products were chosen as markers of the release of singlet oxygen (1O2) upon reaction of peroxynitrous acid with hydrogen peroxide. Oxidation of purine bases was then studied within isolated DNA. A significant increase in the level of 8-oxo-dGuo, oxazolone and 8-oxo-dAdo was observed within double stranded DNA upon exposure to gamma-radiation. Oxazolone and 8-oxo-dAdo were formed upon peroxynitrite treatment but no significant increase in the amount of 8-oxo-dGuo was detected. These results showed that peroxynitrite exhibits oxidizing properties toward purine moieties both in nucleosides and isolated DNA. However, the significant differences in the oxidative damage distribution within DNA observed after exposure to gamma radiation by comparison with peroxynitrite treatment questions the involvement of hydroxyl radicals as the main oxidizing species released by decomposition of peroxynitrous acid.
一氧化氮与超氧阴离子反应生成高反应活性物质过氧亚硝酸盐（ONOO-）。已证明该化合物是脂质和蛋白质的强氧化剂。然而，除了诱导链断裂外，尚无关于其对DNA作用的数据。我们报告了过氧亚硝酸盐与核苷及分离的DNA中的腺嘌呤和鸟嘌呤部分反应的研究结果。对样品进行了8-氧代-7,8-二氢-2'-脱氧鸟苷（8-氧代-dGuo）、2,2-二氨基-4-[(2-脱氧-β-D-赤藓糖基)氨基]-5-(2H)-恶唑酮（恶唑酮）和8-氧代-7,8-二氢-2'-脱氧腺苷（8-氧代-dAdo）的分析。将过氧亚硝酸盐处理的效果与作为羟基自由基来源的通气水溶液中的电离辐射的效果进行了比较。在核苷水平上，两种氧化条件均导致恶唑酮和8-氧代-dAdo的形成。此外，还提供了4-羟基-8-氧代-4,8-二氢-2'-脱氧鸟苷的4R和4S非对映异构体形成的证据。后一种dGuo氧化产物被选作过氧亚硝酸与过氧化氢反应时单线态氧（1O2）释放的标志物。然后在分离的DNA中研究嘌呤碱基的氧化。双链DNA暴露于γ辐射后，8-氧代-dGuo、恶唑酮和8-氧代-dAdo的水平显著增加。过氧亚硝酸盐处理后形成了恶唑酮和8-氧代-dAdo，但未检测到8-氧代-dGuo的量有显著增加。这些结果表明，过氧亚硝酸盐在核苷和分离的DNA中均对嘌呤部分表现出氧化特性。然而，与过氧亚硝酸盐处理相比，暴露于γ辐射后在DNA内观察到的氧化损伤分布的显著差异，对羟基自由基作为过氧亚硝酸分解释放的主要氧化物种的参与提出了质疑。
