Edaravone is a heterocyclic pyrazolone compound. It has pronounced effect against free radicals, however renal and hepatic disorders have been reported. Isoxazolones are considered bioisosteric analogues of pyrazolones and may have comparable properties. Thus, we investigated the structural and electronic influences for edaravone, isoxazolone, and their tautomers on antioxidant process. Structure and tautomerism study among edaravone, isoxazolone and their heterocycles derivatives were related to antioxidant mechanisms by using the hybrid DFT method B3LYP with the basis sets 6-31++G(2d,2p). The CH tautomer was the most stable and energetically favored among them. Intramolecular NHN hydrogen bonds and polar medium were responsible for the low energy differences among all possible tautomers. NH tautomers in both systems proved to be better antioxidant by SET (single electron transfer), while OH tautomers were better antioxidant on HAT (homolytic hydrogen atom transfer) mechanism. Theoretical calculation showed that edaravone is more potent than phenylisoxazolone, however, both has similar antioxidant scavenging on experimental DPPH. The carbonyliminic system played a very important role in the antioxidant activity for both studied classes.

依达拉奉是杂环吡唑啉酮化合物。它对自由基有明显的作用，但是有肾脏和肝脏疾病的报道。异恶唑酮被认为是吡唑啉酮的生物立体异构体，并且可能具有可比的特性。因此，我们研究了依达拉奉，异恶唑酮及其互变异构体在抗氧化过程中的结构和电子影响。依达拉奉，异恶唑酮及其杂环衍生物之间的结构和互变异构现象的研究，是通过以6-31 ++ G（2d，2p）为基础的混合DFT方法B3LYP进行的。其中的C H互变异构体是最稳定和最受能量欢迎的。分子内的N H N氢键和极性介质是所有可能的互变异构体之间低能量差异的原因。ñ在两个系统中，H互变异构体通过SET（单电子转移）证明是更好的抗氧化剂，而O H互变异构体在HAT（均溶氢原子转移）机理上是更好的抗氧化剂。理论计算表明，依达拉奉比苯基异恶唑酮更有效，但是两者在实验DPPH上具有相似的抗氧化剂清除能力。对于两个研究类别，羰基亚胺基体系在抗氧化活性中都起着非常重要的作用。