Quinoid derivatives of the nevirapine metabolites 2-hydroxy- and 3-hydroxy-nevirapine: activation pathway to amino acid adducts
Quinoid derivatives of the nevirapine metabolites 2-hydroxy- and 3-hydroxy-nevirapine: activation pathway to amino acid adducts
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DOI：
10.1039/c5tx00176e
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发表时间：
2015-01-01
影响因子：
2.1
通讯作者：
Antunes, Alexandra M. M.
中科院分区：
文献类型：
--
作者：
Harjivan, Shrika G.;Pinheiro, Pedro F.;Antunes, Alexandra M. M.
奈韦拉平（NVP）是发展中国家最常用的非核苷类HIV-1逆转录酶抑制剂，既作为联合抗逆转录病毒治疗的组成部分，也用于预防病毒的母婴传播;然而，严重的肝毒性和严重的皮肤不良反应引起了对其安全性的担忧。NVP代谢产生几种酚类衍生物，可以想象，这些酚类衍生物能够进一步代谢氧化为亲电子醌类衍生物，这些衍生物易于与生物亲核体反应并引发毒性反应。我们研究了两种酚类NVP代谢产物2-羟基-NVP和3-羟基-NVP进行氧化并随后与生物亲核体反应的能力。两种代谢产物在水介质中用Fremy盐氧化后产生相同的环收缩产物。这与2，3-NVP-醌中间体的形成一致，其在通过还原稳定后通过质谱法和核磁共振光谱法完全表征。此外，我们确定2-羟基-NVP的氧化活化涉及醌和醌亚胺的瞬时形成，而3-羟基-NVP选择性地转化为2，3-NVP-醌。还研究了2-羟基-NVP和3-羟基-NVP在模型氨基酸缬氨酸乙酯（模拟血红蛋白的高反应性N-末端缬氨酸）和N-乙酰半胱氨酸存在下的氧化。缬氨酸乙酯与2，3-NVP-醌和NVP-醌-亚胺反应，产生共价加合物。相比之下，2，3-NVP-醌和NVP衍生的醌-亚胺均不与N-乙酰半胱氨酸反应。用髓过氧化物酶介导的氧化复制了在存在缬氨酸乙酯的情况下2-羟基-NVP的Fremy盐氧化后观察到的产物谱。此外，酪氨酸酶介导的氧化选择性地产生2，3-NVP-醌衍生的产物，而醌亚胺衍生的产物在乳过氧化物酶催化后获得。这些观察结果表明，酚类NVP代谢物代谢转化为醌型亲电体在生物学上是合理的。此外，缺乏与巯基的反应可能会阻碍NVP衍生的醌和醌亚胺代谢物通过谷胱甘肽缀合的体内解毒。因此，这些代谢物可用于与氮基生物亲核体（例如，蛋白质的赖氨酸残基）最终引发毒性事件。
Nevirapine (NVP) is the non-nucleoside HIV-1 reverse transcriptase inhibitor most commonly used in developing countries, both as a component of combined antiretroviral therapy and to prevent mother-to-child transmission of the virus; however, severe hepatotoxicity and serious adverse cutaneous effects raise concerns about its safety. NVP metabolism yields several phenolic derivatives conceivably capable of undergoing further metabolic oxidation to electrophilic quinoid derivatives prone to react with bionucleophiles and initiate toxic responses. We investigated the ability of two phenolic NVP metabolites, 2-hydroxy-NVP and 3-hydroxy-NVP, to undergo oxidation and subsequent reaction with bionucleophiles. Both metabolites yielded the same ring-contraction product upon oxidation with Fremy's salt in aqueous medium. This is consistent with the formation of a 2,3-NVP-quinone intermediate, which upon stabilization by reduction was fully characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. Additionally, we established that the oxidative activation of 2-hydroxy-NVP involved the transient formation of both the quinone and a quinone-imine, whereas 3-hydroxy-NVP was selectively converted into 2,3-NVP-quinone. The oxidations of 2-hydroxy-NVP and 3-hydroxy-NVP in the presence of the model amino acids ethyl valinate (to mimic the highly reactive N-terminal valine of hemoglobin) and N-acetylcysteine were also investigated. Ethyl valinate reacted with both 2,3-NVP-quinone and NVP-quinone-imine, yielding covalent adducts. By contrast, neither 2,3-NVP-quinone nor NVP-derived quinone-imine reacted with N-acetylcysteine. The product profile observed upon Fremy's salt oxidation of 2-hydroxy-NVP in the presence of ethyl valinate was replicated with myeloperoxidase-mediated oxidation. Additionally, tyrosinase-mediated oxidations selectively yielded 2,3-NVP-quinone-derived products, while quinone-imine-derived products were obtained upon lactoperoxidase catalysis. These observations suggest that the metabolic conversion of phenolic NVP metabolites into quinoid electrophiles is biologically plausible. Moreover, the lack of reaction with sulfhydryl groups might hamper the in vivo detoxification of NVP-derived quinone and quinone-imine metabolites via glutathione conjugation. As a result, these metabolites could be available for reaction with nitrogen-based bionucleophiles (e.g., lysine residues of proteins) ultimately eliciting toxic events.