Damiani E, Carloni P, Stipa P, Greci L
Dipartimento di Scienze dei Materiali e della Terra, Università, Ancona, Italy.
Free Radic Res. 1999 Aug;31(2):113-21. doi: 10.1080/10715769900301621.
The increasing knowledge on the participation of free radicals in many diverse clinical and pathological conditions, has consequently expanded the search for new and versatile antioxidants aimed at combating oxidative stress. Our interest in this field concerns aromatic indolinonic aminoxyls (nitroxides) which efficiently react with alkoxyl, peroxyl, aminyl, arylthiyl and alkyl radicals to give non-paramagnetic species. This prompted us to test their antioxidant activity on different biological systems exposed to free radical-induced oxidative stress and the results obtained so far have been very promising. However little is known about their behaviour towards superoxide and hydroxyl radicals. Here, we report on the reactivity of an indolinonic aminoxyl, with the two above mentioned radicals using hypoxanthine/xanthine oxidase and potassium superoxide for generating the former and the Fenton reagent for the latter. Besides performing the deoxyribose assay for studying the reaction of the aminoxyl with hydroxyl radical and monitoring spectral changes of the aminoxyl in the presence of superoxide radical, macroscale reactions were performed in both cases and the products of the reactions isolated and identified. The EPR technique was used in this study to help elucidate the data obtained. The results show that this compound efficiently reacts with both hydroxyl and superoxide radicals and furthermore, it is capable of maintaining iron ions in its oxidized form. The results thus contribute to increasing the knowledge on the reactivity of indolinonic aminoxyls towards free radical species and as a consequence, these compounds and/or other aminoxyl derivatives, may be considered as complementary, and sometimes alternative sources for combating oxidative damage.
随着对自由基在多种临床和病理状况中所起作用的认识不断增加，人们对新型多功能抗氧化剂的探索也随之扩大，旨在对抗氧化应激。我们对该领域的兴趣集中在芳香吲哚啉氮氧自由基（氮氧化物）上，它们能与烷氧基、过氧基、氨基自由基、芳硫基和烷基自由基高效反应，生成顺磁性物质。这促使我们在暴露于自由基诱导的氧化应激的不同生物系统中测试它们的抗氧化活性，到目前为止所获得的结果非常有前景。然而，关于它们对超氧阴离子自由基和羟基自由基的反应行为却知之甚少。在此，我们报道一种吲哚啉氮氧自由基与上述两种自由基的反应活性，使用次黄嘌呤/黄嘌呤氧化酶和超氧化钾生成前者，使用芬顿试剂生成后者。除了进行脱氧核糖分析以研究氮氧自由基与羟基自由基的反应，并监测超氧阴离子自由基存在时氮氧自由基的光谱变化外，在这两种情况下都进行了大规模反应，并对反应产物进行了分离和鉴定。本研究使用电子顺磁共振（EPR）技术来辅助阐明所获得的数据。结果表明，该化合物能与羟基自由基和超氧阴离子自由基高效反应，此外，它还能够使铁离子保持氧化态。因此，这些结果有助于增加对吲哚啉氮氧自由基与自由基物种反应活性的了解，结果，这些化合物和/或其他氮氧自由基衍生物可被视为对抗氧化损伤的补充，有时甚至是替代来源。
