Several antihistamine drugs including terfenadine, ebastine, and astemizole have been identified as substrates for CYP2J2. The overall importance of this enzyme in drug metabolism has not been fully explored. In this study, 139 marketed therapeutic agents and compounds were screened as potential CYP2J2 substrates. Eight novel substrates were identified that vary in size and overall topology from relatively rigid structures (amiodarone) to larger complex structures (cyclosporine). The substrates displayed in vitro intrinsic clearance values ranging from 0.06 to 3.98 μl/min/pmol CYP2J2. Substrates identified for CYP2J2 are also metabolized by CYP3A4. Extracted ion chromatograms of metabolites observed for albendazole, amiodarone, astemizole, thioridazine, mesoridazine, and danazol showed marked differences in the regioselectivity of CYP2J2 and CYP3A4. CYP3A4 commonly metabolized compounds at multiple sites, whereas CYP2J2 metabolism was more restrictive and limited, in general, to a single site for large compounds. Although the CYP2J2 active site can accommodate large substrates, it may be more narrow than CYP3A4, limiting metabolism to moieties that can extend closer toward the active heme iron. For albendazole, CYP2J2 forms a unique metabolite compared with CYP3A4. Albendazole and amiodarone were evaluated in various in vitro systems including recombinant CYP2J2 and CYP3A4, pooled human liver microsomes (HLM), and human intestinal microsomes (HIM). The Michaelis-Menten-derived intrinsic clearance of N -desethyl amiodarone was 4.6 greater in HLM than in HIM and 17-fold greater in recombinant CYP3A4 than in recombinant CYP2J2. The resulting data suggest that CYP2J2 may be an unrecognized participant in first-pass metabolism, but its contribution is minor relative to that of CYP3A4.
几种
抗组胺药物,包括
特非那定、依巴斯丁和
阿斯特米唑,已被确定为CYP2J2的底物。然而,该酶在药物代谢中的整体重要性尚未完全探讨。在这项研究中,筛选了139种市场上销售的治疗药物和化合物作为潜在的CYP2J2底物。鉴定出8种新型底物,它们在大小和整体拓扑结构上有所不同,从相对刚性的结构(
氨碘索)到较大的复杂结构(
环孢素)。这些底物在体外表现出内源性清除率值范围为0.06到3.98 μl/min/pmol CYP2J2。为CYP2J2鉴定的底物也被CYP3A4代谢。对醚
氟烯、
氨碘索、
阿斯特米唑、噻
吩噻嗪、美索
噻嗪和
达那唑的代谢物提取离子色谱图显示CYP2J2和CYP3A4的区域选择性存在显著差异。CYP3A4通常在多个位点代谢化合物,而CYP2J2的代谢则更为限制,通常仅限于大化合物的单个位点。尽管CYP2J2的活性位点可以容纳较大的底物,但可能比CYP3A4更窄,从而限制了代谢的分子延伸至活性血红素
铁的距离。对于醚
氟烯,CYP2J2形成一种与CYP3A4不同的独特代谢物。醚
氟烯和
氨碘索在各种体外系统中进行了评估,包括
重组CYP2J2和CYP3A4、 pooled人肝微粒体(HLM)和人肠道微粒体(HIM)。N-去乙基
氨碘索的迈克利斯-门腾推导内源性清除率在HLM中比在HIM中高出4.6倍,在
重组CYP3A4中比在
重组CYP2J2中高出17倍。结果数据表明,CYP2J2可能是首过代谢中未被识别的参与者,但与CYP3A4相比,其贡献相对较小。