Identification of Uridine 5′-Diphosphate-Glucuronosyltransferases Responsible for the Glucuronidation of Mirabegron, a Potent and Selective β3-Adrenoceptor Agonist, in Human Liver Microsomes
作者:Kentaro Konishi、Daisuke Tenmizu、Shin Takusagawa
DOI:10.1007/s13318-017-0450-x
日期:2018.6
Mirabegron is cleared by multiple mechanisms, including drug-metabolizing enzymes. One of the most important clearance pathways is direct glucuronidation. In humans, M11 (O-glucuronide), M13 (carbamoyl-glucuronide), and M14 (N-glucuronide) have been identified, of which M11 is one of the major metabolites in human plasma. The objective of this study was to identify the uridine 5′-diphosphate (UDP)-glucuronosyltransferase (UGT) isoform responsible for the direct glucuronidation of mirabegron using human liver microsomes (HLMs) and recombinant human UGTs (rhUGTs). Reaction mixtures contained 1–1000 μM mirabegron, 8 mM MgCl2, alamethicin (25 μg/mL), 50 mM Tris–HCl buffer (pH 7.5), human liver microsome (HLM) or rhUGT (1.0 mg protein/mL), and 2 mM UDP-glucuronic acid in a total volume of 200 μL for 120 min at 37 °C. HLMs from 16 individuals were used for the correlation study, and mefenamic acid and propofol were used for the inhibition study. Regarding M11 formation, rhUGT2B7 showed high activity among the rhUGTs tested (11.3 pmol/min/mg protein). This result was supported by the correlation between M11 formation activity and UGT2B7 marker enzyme activity (3-glucuronidation of morphine, r 2 = 0.330, p = 0.020) in individual HLMs; inhibition by mefenamic acid in pooled HLMs (IC50 = 22.8 μM); and relatively similar K m values between pooled HLMs and rhUGT2B7 (1260 vs. 486 μM). Regarding M13 and M14 formation, rhUGT1A3 and rhUGT1A8 showed high activity among the rhUGTs tested, respectively. UGT2B7 is the main catalyst of M11 formation in HLMs. Regarding M13 and M14 formation, UGT1A3 and UGT1A8 are strong candidates for glucuronidation, respectively.
米拉贝隆通过多种机制清除,包括药物代谢酶。最主要的清除途径之一是直接葡糖醛酸化。在人类中,已鉴定出M11(O-葡糖苷酸),M13(氨基甲酰-葡糖苷酸)和M14(N-葡糖苷酸),其中M11是人类血浆中的主要代谢物之一。本研究旨在使用人肝微粒体(HLM)和重组人UGTs(rhUGTs)识别负责米拉贝隆直接葡糖醛酸化的尿苷5'-二磷酸(UDP)-葡糖醛酸基转移酶(UGT)同工酶。反应混合物包含1-1000 μM的米拉贝隆,8 mM MgCl2,白粉菌素(25 μg/mL),50 mM Tris-HCl缓冲液(pH 7.5),人肝微粒体(HLM)或rhUGT(1.0 mg蛋白/mL),以及2 mM UDP-葡萄糖醛酸,总体积为200 μL,在37 °C下反应120分钟。从16个人中使用的HLMs进行了相关性研究,并使用甲芬那酸和丙泊酚进行了抑制研究。关于M11形成,在测试的rhUGT中,rhUGT2B7表现出高活性(11.3 pmol/min/mg蛋白)。这个结果得到了个体HLM中M11形成活性和UGT2B7标记酶活性(吗啡的3-葡糖醛酸化,r 2 = 0.330,p = 0.020)之间的相关性;池化HLMs中甲芬那酸的抑制作用(IC50 = 22.8 μM);以及池化HLMs和rhUGT2B7之间的相对相似的K m值(1260 vs. 486 μM)的支持。关于M13和M14形成,在测试的rhUGT中,rhUGT1A3和rhUGT1A8分别表现出高活性。UGT2B7是HLMs中M11形成的主要催化剂。关于M13和M14形成,UGT1A3和UGT1A8分别是葡糖醛酸化的强有力候选者。