Evidence for the bioactivation of zomepirac and tolmetin by an oxidative pathway: Identification of glutathione adducts in vitro in human liver microsomes and in vivo in rats
Evidence for the bioactivation of zomepirac and tolmetin by an oxidative pathway: Identification of glutathione adducts in vitro in human liver microsomes and in vivo in rats
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DOI：
10.1124/dmd.105.004341
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发表时间：
2006-01-01
影响因子：
3.9
通讯作者：
Tang, W
中科院分区：
文献类型：
--
作者：
Chen, Q;Doss, GA;Tang, W
尽管佐美拉克（ZP）和托美丁（TM）会引起过敏反应并形成反应性酰基葡萄糖醛酸苷，但这两个事件之间的直接联系仍然不清楚。我们在此报道，除了酰基葡萄糖醛酸化之外，两种药物都受到氧化生物活化。将 ZP 与添加了 NADPH 和谷胱甘肽 (GSH) 的人肝微粒体一起孵育后，通过 LC/MS/MS 检测到 m/z 597 处具有 MH+ 离子的代谢物。根据碰撞诱导解离和 NMR 证据，该代谢物的结构被确定为 5-[4'-氯苯甲酰]1,4-二甲基-3-谷胱甘肽吡咯-2-乙酸 (ZP-SG)，表明 ZP 的吡咯部分已氧化成环氧化物中间体，然后添加 GSH 并失去 H2O 元素，产生观察到的缀合物。 ZP 的氧化生物活化很可能是由细胞色素 P450 (P450) 3A4 催化的，因为用酮康唑或抑制性抗 P450 3A4 IgG 预处理人肝微粒体后，ZP-SG 的形成减少至与对照值相似的 10%。当 TM 与人肝微粒体制剂一起孵育时，鉴定出类似的 GSH 加合物，即 5-[4'-甲基苯甲酰]-1-甲基-3-谷胱甘肽吡咯-2-乙酸 (TM-SG)。这些体外研究结果与体内情况的相关性是通过在分别用 ZP 和 TM 治疗的大鼠中检测相同的硫醇加合物来确定的。总而言之，这些数据表明，除了酰基葡萄糖醛酸苷的形成之外，ZP 和 TM 的氧化代谢还提供了可能使蛋白质半抗原化的活性物质，从而有助于药物介导的过敏反应。
Although zomepirac ( ZP) and tolmetin ( TM) induce anaphylactic reactions and form reactive acyl glucuronides, a direct link between the two events remains obscure. We report herein that, in addition to acyl glucuronidation, both drugs are subject to oxidative bioactivation. Following incubations of ZP with human liver microsomes fortified with NADPH and glutathione ( GSH), a metabolite with an MH+ ion at m/z 597 was detected by LC/MS/MS. On the basis of collision-induced dissociation and NMR evidence, the structure of this metabolite was determined to be 5-[4'-chlorobenzoyl]1,4-dimethyl-3-glutathionylpyrrole-2-acetic acid ( ZP-SG), suggesting that the pyrrole moiety of ZP had undergone oxidation to an epoxide intermediate, followed by addition of GSH and loss of the elements of H2O to yield the observed conjugate. The oxidative bioactivation of ZP most likely is catalyzed by cytochrome P450 ( P450) 3A4, since the formation of ZP-SG was reduced to similar to 10% of control values following pretreatment of human liver microsomes with ketoconazole or with an inhibitory anti-P450 3A4 IgG. A similar GSH adduct, namely 5-[4'-methylbenzoyl]-1-methyl-3-glutathionylpyrrole-2-acetic acid ( TM-SG), was identified when TM was incubated with human liver microsomal preparations. The relevance of these in vitro findings to the in vivo situation was established through the detection of the same thiol adducts in rats treated with ZP and TM, respectively. Taken together, these data suggest that, in addition to the formation of acyl glucuronides, oxidative metabolism of ZP and TM affords reactive species that may haptenize proteins and thereby contribute to the drug-mediated anaphylactic reactions.