Chen Yuan, Liu Hua-fen, Liu Liling, Nguyen Khanh, Jones Elliott B, Fretland Adrian J
Department of Drug Metabolism and Pharmacokinetics, Roche Palo Alto, Palo Alto, CA, USA.
Xenobiotica. 2010 Aug;40(8):536-46. doi: 10.3109/00498254.2010.492880.
The involvement of cytochrome P450 2B6 (CYP2B6) to the in vitro and in vivo metabolism of bupropion has been well studied. In these investigations we performed a detailed in vitro phenotyping study to characterize isoforms other than CYP2B6. A total of nine metabolites were identified (M1-M9) in the incubations with cDNA-expressed P450s (rhCYP) and human liver microsomes (HLM). Incubations in rhCYP identified CYP2B6 as the isoform responsible for the formation of hydroxybupropion (M3). CYP2C19 was involved in bupropion metabolism primarily through alternate hydroxylation pathways (M4-M6) with higher activity at lower substrate concentrations, near 1 microM. The results from HLM inhibition studies using CYP2B6 and CYP2C19 inhibitory antibodies indicated that CYP2B6 contributed to approximately 90% of M3 formation, and CYP2C19 contributed to approximately 70-90% of M4, M5, and M6 formation. Studies using single donor HLM with varying degrees of CYP2B6 and CYP2C19 activities showed a good relationship between M3 formation and CYP2B6 activity and M4/M5 formation and CYP2C19 activity. These results confirmed the principle role of CYP2B6 in hydroxybupropion formation, as a selective CYP2B6 probe. In addition, the new findings revealed that CYP2C19 also contributes to bupropion metabolism through alternate hydroxylation pathways.
细胞色素P450 2B6（CYP2B6）参与安非他酮的体外和体内代谢已得到充分研究。在这些研究中，我们进行了一项详细的体外表型研究，以表征除CYP2B6之外的其他同工酶。在用cDNA表达的P450（重组人细胞色素P450，rhCYP）和人肝微粒体（HLM）进行的孵育中，共鉴定出9种代谢产物（M1 - M9）。在rhCYP孵育中，CYP2B6被确定为负责形成羟基安非他酮（M3）的同工酶。CYP2C19主要通过交替羟基化途径（M4 - M6）参与安非他酮代谢，在较低底物浓度（接近1微摩尔）时活性较高。使用CYP2B6和CYP2C19抑制性抗体进行的HLM抑制研究结果表明，CYP2B6约占M3形成的90%，CYP2C19约占M4、M5和M6形成的70 - 90%。使用具有不同程度CYP2B6和CYP2C19活性的单供体HLM进行的研究表明，M3形成与CYP2B6活性以及M4/M5形成与CYP2C19活性之间存在良好的相关性。这些结果证实了CYP2B6作为选择性CYP2B6探针在羟基安非他酮形成中的主要作用。此外，新发现表明CYP2C19也通过交替羟基化途径参与安非他酮代谢。
