Discovery of a Highly Selective CYP3A4 Inhibitor Suitable for Reaction Phenotyping Studies and Differentiation of CYP3A4 and CYP3A5
作者:Xiaohai Li、Xinyi Song、Theodore M. Kamenecka、Michael D. Cameron
DOI:10.1124/dmd.112.046144
日期:2012.9
Current molecular tools lack the ability to differentiate the activity of CYP3A4 and CYP3A5 in biological samples such as human liver microsomes. Kinetic experiments and the CYP3A4 crystal structure indicate that the active sites of both enzymes are large and flexible, and have more than one binding subsite within the active site. 1-(4-Imidazopyridinyl-7phenyl)-3-(4′-cyanobiphenyl) urea (SR-9186) was optimized through several rounds of structural refinement from an initial screening hit to obtain greater than 1000-fold selectivity for the inhibition of CYP3A4 versus CYP3A5. Characterization data demonstrate selectivity using midazolam and testosterone hydroxylation assays with recombinant cytochrome P450, pooled human liver microsomes, and individually genotyped microsomes. Clear differences are seen between individuals with CYP3A5 * 1 and * 3 genotypes. The antifungal drug ketoconazole is the most commonly used CYP3A inhibitor for in vitro and in vivo studies. A direct comparison of SR-9186 and ketoconazole under typical assay conditions used in reaction phenotyping studies demonstrated that SR-9186 had selectivity over CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A5 greater than or equal to that of ketoconazole. In addition, the long half-life (106 min) of SR-9186 in incubations containing 1 mg/ml human liver microsomes provided sustained CYP3A4 inhibition.
目前的分子工具无法区分人体肝脏微粒体等生物样本中 CYP3A4 和 CYP3A5 的活性。动力学实验和 CYP3A4 晶体结构表明,这两种酶的活性位点都很大而且很灵活,在活性位点内有不止一个结合子位点。1-(4-Imidazopyridinyl-7phenyl)-3-(4′-cyanobiphenyl) urea (SR-9186)从最初的筛选结果开始,经过几轮结构优化,在抑制 CYP3A4 和 CYP3A5 的选择性上提高了 1000 倍以上。表征数据显示,利用重组细胞色素 P450、集合人类肝脏微粒体和单个基因分型微粒体进行咪达唑仑和睾酮羟化测定,该化合物具有选择性。CYP3A5 * 1 和 * 3 基因型的个体之间存在明显差异。抗真菌药物酮康唑是体外和体内研究中最常用的 CYP3A 抑制剂。在反应表型研究中使用的典型检测条件下对 SR-9186 和酮康唑进行的直接比较表明,SR-9186 对 CYP1A2、CYP2A6、CYP2B6、CYP2C8、CYP2C9、CYP2C19、CYP2D6、CYP2E1 和 CYP3A5 的选择性大于或等于酮康唑。此外,SR-9186 在含有 1 毫克/毫升人类肝脏微粒体的培养液中具有较长的半衰期(106 分钟),可持续抑制 CYP3A4。