Zhang Xiuwen, Jiang Peng, Chen Ping, Cheng Nengneng
a Department of Pharmacology , School of Pharmacy, Fudan University , Shanghai , China.
Pharm Biol. 2016;54(4):619-27. doi: 10.3109/13880209.2015.1070876. Epub 2015 Oct 1.
Kurarinone, the most abundant prenylated flavonoid in Sophora flavescens Aiton (Leguminosae), is a promising antitumor therapeutic. However, it shows significant hepatotoxicity. Furthermore, how kurarinone is metabolized in humans remains unclear.
The objective of this study is to investigate kurarinone metabolism in human liver microsomes (HLMs) and the role of metabolism in kurarinone-induced cytotoxicity.
The UDP-glucuronosyltransferase isoforms (UGTs) involved in kurarinone glucuronidation were identified using chemical inhibitors (100-1000 µM phenylbutazone; 10-100 µM β-estradiol; 10-100 µM 1-naphthol; 10-500 µM propofol; and 100-1000 µM fluconazole) and recombinant human UGTs. Kurarinone (2-500 µM) was incubated with HLMs and UGTs (0.5 mg/mL) for 15 min to determine enzyme kinetic parameters. The IC50 value of kurarinone (10-200 µM) was evaluated in a HLMs/3T3 cell co-culture system.
Kurarinone is extensively converted to two glucuronides (M3 and M4) in HLMs. M3 formation was catalyzed by multiple UGT1As, with UGT1A3 showing the highest intrinsic clearance (120.60 mL/min/mg). M4 formation was catalyzed by UGT1A1, UGT2B4, and UGT2B7. UGT1A1 showed the highest intrinsic clearance (60.61 mL/min/mg). The kinetic profiles of the five main UGTs and HLMs fit substrate inhibition kinetics, with Km values ranging from 5.20 to 46.52 µM, Vmax values ranging from 0.20 to 3.06 µmol/min/mg, and Ksi values ranging from 25.58 to 230.30 µM. The kurarinone IC50 value was 93 μM in the control group, 102 μM in HLMs with NADPH, and 160 μM in HLMs with UDPGA.
Kurarinone glucuronidation is a detoxification pathway. This information may help to elucidate the risk factors regulating kurarinone toxicity.
苦参素是苦参（豆科）中含量最丰富的异戊烯基黄酮，是一种有前景的抗肿瘤治疗药物。然而，它具有显著的肝毒性。此外，苦参素在人体内的代谢方式仍不清楚。
本研究旨在研究苦参素在人肝微粒体（HLMs）中的代谢情况以及代谢在苦参素诱导的细胞毒性中的作用。
使用化学抑制剂（100 - 1000 μM保泰松；10 - 100 μMβ-雌二醇；10 - 100 μM 1 - 萘酚；10 - 500 μM丙泊酚；100 - 1000 μM氟康唑）和重组人尿苷二磷酸葡萄糖醛酸基转移酶（UGTs）鉴定参与苦参素葡萄糖醛酸化的UGT同工酶。将苦参素（2 - 500 μM）与HLMs和UGTs（0.5 mg/mL）孵育15分钟以确定酶动力学参数。在HLMs/3T3细胞共培养系统中评估苦参素（10 - 200 μM）的半数抑制浓度（IC50）值。
苦参素在HLMs中广泛转化为两种葡萄糖醛酸苷（M3和M4）。M3的形成由多种UGT1A催化，其中UGT1A3显示出最高的内在清除率（120.60 mL/min/mg）。M4的形成由UGT1A1、UGT2B4和UGT2B7催化。UGT1A1显示出最高的内在清除率（60.61 mL/min/mg）。五种主要UGT和HLMs的动力学曲线符合底物抑制动力学，米氏常数（Km）值范围为5.20至46.52 μM，最大反应速度（Vmax）值范围为0.20至3.06 μmol/min/mg，底物抑制常数（Ksi）值范围为25.58至230.30 μM。对照组中苦参素的IC50值为93 μM，添加烟酰胺腺嘌呤二核苷酸磷酸（NADPH）的HLMs中为102 μM，添加尿苷二磷酸葡萄糖醛酸（UDPGA）的HLMs中为160 μM。
苦参素葡萄糖醛酸化是一条解毒途径。这些信息可能有助于阐明调节苦参素毒性的危险因素。
