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中国临床药理学与治疗学 ›› 2007, Vol. 12 ›› Issue (11): 1255-1260.

• 基础研究 • 上一篇    下一篇

大鼠肝微粒体CYP3A1/2 和CYP2C9/10参与甘草次酸羟化代谢

高凯1, 余伟2, 杨静2, 段徐华2   

  1. 1湖北省妇幼保健院药剂科, 武汉430070, 湖北;
    2武汉大学医学院药理学系, 武汉430071, 湖北
  • 收稿日期:2007-05-11 修回日期:2007-08-28 发布日期:2020-11-04
  • 通讯作者: 杨静, 男, 教授, 博士生导师, 主要从事分子药理和药物代谢研究。Tel:027-87331565 E-mail: yangjingliu@yahoo.com.cn
  • 作者简介:高凯, 女, 主管药师, 主要从事医院药学工作。Tel:027-87169247 E-mail: gyhu1013@sohu.com

CYP3A1/2 and 2C9/10 in rat liver microsomes mediate 22α-and 24-hydroxylation of 18α-glycyrrhetic acid

GAO Kai1, WEI Yu2, YANG Jing2, DUAN Xu-hua2   

  1. 1Department of Pharmacy,Hubei Maternal and Child Health Hospital,Wuhan 430070,Hubei,China;
    2Department of Pharmacology,Medical College of WuhanUniversity,Wuhan 430071,Hubei,China
  • Received:2007-05-11 Revised:2007-08-28 Published:2020-11-04

摘要: 目的: 对参与18α-甘草次酸(GA) 羟化代谢的细胞色素P450(cytochrome P450, CYP) 亚型进行研究。方法: 采用大鼠肝微粒体体外代谢GA 的孵育方法和高效液相色谱(HPLC) 技术, 通过分析甘草次酸在肝微粒体中形成的单羟化代谢物的酶促动力学, 分析其酶学模型, 然后用不同的CYP 同工酶选择性抑制剂和底物进行抑制实验, 初步选出介导甘草次酸单羟化代谢所涉及的CYP 同工酶。结果: 大鼠肝微粒体羟化代谢GA 呈反应时间(10 ~ 40 min), 底物浓度(25 ~ 200 μmol/L) 和蛋白浓度(0.25 ~1.0 g/L) 依赖性。GA 代谢为22α-羟-GA 和24-羟-GA的Vmax分别为(7.9±1.4) μmol·min-1·g-1和(3.4±1.0) μmo1·min-1 ·g-1, Km 分别为(33±9) μmol/L 和(68±18) μmol/L 。抑制性研究可见:TAO 和Ery 剂量依赖性抑制22α-羟-GA 形成, 最大抑制率分别为82.4 %和45.7 %, 而Sul 无显著抑制作用;Sul 剂量依赖性抑制24-羟-GA 形成, 抑制率依次为26.8 %、45.3 %和69.5 %, 而TAO 和Ery 的抑制作用不显著。红霉素N-脱甲基酶活性与22α-羟化代谢速率高度相关(r =0.864, P<0.01, n =10),与24-羟化代谢速率无明显相关(r =0.310, P>0.05, n =10) 。结论: 大鼠肝微粒体CYP3A1/2 和CYP2C9/10 分别参与了GA 的C-22α和C-24 羟化代谢。

关键词: 18α-甘草次酸, 高效液相色谱, 体外代谢, 肝微粒体

Abstract: AIM: To identify the cytochrome P450 isoforms involved in 22 α-hydroxylation and 24-hydroxylation of 18α-glycyrrhetic acid (GA) in rat livers. METHODS: Kinetic analysis of the rates of formation of monohydroxylated metabolites of GA, including 22 α-hydro-GA and 24-hydro-GA, was performed using rat liver microsomes at substrate concentrations ranging from 25 to 200 μmol/L. Seven selective inhibitors or substrate probes specific for different CYP isoforms were applied for screening the isoform (s) responsible for mono-hydroxylated metabolism of GA hydroxylate. RESULTS: The formation of metabolites of GA depended on incubation time(10-40 min),substrate concentration (25-200 μmol/L) and microsome protein concentration (0.25-1.0 g/L). The kinetic behaviors of 22α-hydroxylation and 24-hydroxylation of GA were described well by a Michaelis-Menten equation [Vmax were (7.89±1.43) and (3.38±0.95) μmol·min-1·g-1,Km was (33.5±8.6) and (67.8±17.9) μmol/L, respectively]. Inhibition experiments showed that troleandomycin (6.25-100 μmol/L and erythromycin (15.7-250 μmol/L) as potent CYP3A1/2 inhibitors, reduced 22α-hydroxylation in a dose-dependent manner (the maximum inhibitory rates were 82.4 % and 45.7 %, respectively),while sulfaphenazole, which was an inhibitor towards 2C9/10 did not display significant inhibition. 22α-hydroxylation of GA correlated well with erythromycin N-demethylase activities (r =0.864, P<0.01, n =10). Sulfaphenazole (6.25-100 μmol/L) as potent CYP2C9/10 inhibitors, reduced 24-hydroxylation of GA in a dose-dependent manner, the maximum inhibitory rate was 69.5 %, while troleandomycin, which were inhibitors as CYP3A1/2 did not display significant inhibition. The 24-hydroxylation of GA did not correlate with erythromycin N-demethylase activities (r = 0.310, P> 0.05, n = 10). CONCLUSION: CYP3A1/2 and CYP2C9/10 in rat liver microsomes mediate the 22α-hydroxylation and 24-hydroxylation of GA.

Key words: 18α-glycyrrhetic acid, HPLC, in vitro metabolism, liver microsomes

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