Stereoselective Flunoxaprofen-<i>S</i>-acyl-glutathione Thioester Formation Mediated by Acyl-CoA Formation in Rat Hepatocytes
作者:Mark P. Grillo、Jill C. M. Wait、Michelle Tadano Lohr、Smriti Khera、Leslie Z. Benet
DOI:10.1124/dmd.109.029371
日期:2010.1
Flunoxaprofen (FLX) is a chiral nonsteroidal anti-inflammatory drug that was withdrawn from clinical use because of concerns of potential hepatotoxicity. FLX undergoes highly stereoselective chiral inversion mediated through the FLX- S -acyl-CoA thioester (FLX-CoA) in favor of the ( R )-(−)-isomer. Acyl-CoA thioester derivatives of acidic drugs are chemically reactive species that are known to transacylate protein nucleophiles and glutathione (GSH). In this study, we investigated the relationship between the stereoselective metabolism of ( R )-(−)- and ( S )-(+)-FLX to FLX-CoA and the subsequent transacylation of GSH forming FLX- S -acyl-glutathione (FLX-SG) in incubations with rat hepatocytes in suspension. Thus, when hepatocytes (2 million cells/ml) were treated with ( R )-(−)- or ( S )-(+)-FLX (100 μM), both FLX-CoA and FLX-SG were detected by sensitive liquid chromatography-tandem mass spectrometry techniques. However, these derivatives were observed primarily from ( R )-(−)-FLX incubation extracts, for which the formation rates of FLX-CoA and FLX-SG were rapid, reaching maximum concentrations of 42 and 2.8 nM, respectively, after 6 min of incubation. Incubations with ( S )-(+)-FLX over 60 min displayed 8.1 and 2.7% as much FLX-CoA and FLX-SG area under the concentration versus time curves, respectively, compared with corresponding incubations with ( R )-(−)-FLX. Coincubation of lauric acid (1000 μM) with ( R )-(−)-FLX (10 μM) led to the complete inhibition of FLX-CoA formation and a 98% inhibition of FLX-SG formation. Reaction of authentic ( R , S )-FLX-CoA (2 μM) with GSH (10 mM) in buffer (pH 7.4, 37°C) showed the quantitative formation of FLX-SG after 3 h of incubation. Together, these results demonstrate the stereoselective transacylation of GSH in hepatocyte incubations containing ( R )-(−)-FLX, which is consistent with bioactivation by stereoselective ( R )-FLX-CoA formation.
氟诺洛芬(FLX)是一种手性非甾体抗炎药物,因担心其潜在的肝毒性而不再用于临床。FLX 通过 FLX- S -酰基-CoA 硫代酯(FLX-CoA)发生高度立体选择性手性反转,有利于 ( R )-(-)- 异构体。酸性药物的酰基-CoA硫酯衍生物是化学反应性物质,可与蛋白质亲核物和谷胱甘肽(GSH)发生反式反应。在这项研究中,我们研究了( R )-(-)- 和 ( S )-(+)-FLX 立体选择性代谢为 FLX-CoA 与随后在悬浮大鼠肝细胞中形成 FLX- S - 乙酰基谷胱甘肽(FLX-SG)的 GSH 反乙酰化之间的关系。因此,用 ( R )-(-)- 或 ( S )-(+)-FLX (100 μM) 处理肝细胞(200 万个细胞/毫升)时,可通过灵敏的液相色谱-串联质谱技术检测到 FLX-CoA 和 FLX-SG。然而,这些衍生物主要是从 ( R )-(-)-FLX 培养液中观察到的,其中 FLX-CoA 和 FLX-SG 的形成速度很快,培养 6 分钟后分别达到 42 nM 和 2.8 nM 的最大浓度。与( R )-(-)-FLX的相应培养相比,( S )-(+)-FLX培养60分钟后,FLX-CoA和FLX-SG的浓度与时间曲线下的面积分别增加了8.1%和2.7%。月桂酸(1000 μM)与( R )-(-)-FLX (10 μM)共孵育可完全抑制 FLX-CoA 的形成,并抑制 98% FLX-SG 的形成。将真品 ( R , S )-FLX-CoA (2 μM) 与 GSH (10 mM) 在缓冲液(pH 7.4,37°C)中反应,结果表明在培养 3 小时后,FLX-SG 定量形成。这些结果共同证明了在含有 ( R )-(-)-FLX 的肝细胞培养液中 GSH 的立体选择性反酰化,这与通过立体选择性 ( R )-FLX-CoA 形成的生物活化是一致的。