甘草次酸在人及大鼠肝微粒体中的体外代谢及其与六种 CYP 底物的相互作用。

In-vitro metabolism of glycyrrhetinic acid by human and rat liver microsomes and its interactions with six CYP substrates.

机构信息

Jiangsu Province Jintan People's Hospital Clinical Laboratory, Jintan Affiliated Hospital of Jiangsu University Clinical Laboratory, Zhenjiang, China.

出版信息

J Pharm Pharmacol. 2012 Oct;64(10):1445-51. doi: 10.1111/j.2042-7158.2012.01516.x. Epub 2012 May 2.

DOI:10.1111/j.2042-7158.2012.01516.x

PMID:22943175

Abstract

OBJECTIVES

Glycyrrhetinic acid is the main metabolite of glycyrrhizin and the main active component of Licorice root. This study was designed to investigate the in-vitro metabolism of glycyrrhetinic acid by liver microsomes and to examine possible metabolic interactions that glycyrrhetinic acid may have with other cytochrome P450 (CYP) substrates.

METHODS

Glycyrrhetinic acid was incubated with rat liver microsomes (RLM) and human liver microsomes (HLM). Liquid chromatography tandem mass spectrometry was used for glycyrrhetinic acid or substrates identification and quantification.

KEY FINDINGS

The K(m) and V(max) values for HLM are 33.41 µm and 2.23 nmol/mg protein/min, respectively; for RLM the K(m) and V(max) were 24.24µm and 6.86 nmol/mg protein/min, respectively. CYP3A4 is likely to be the major enzyme responsible for glycyrrhetinic acid metabolism in HLM while CYP2C9 and CYP2C19 are considerably less active. Other human CYP isoforms have minimal or no activity toward glycyrrhetinic acid. The interactions of glycyrrhetinic acid and six CYP substrates, such as phenacetin, diclofenac, (S)-mephenytoin, dextromethorphan, chlorzoxazone and midazolam were also investigated. The inhibitory action of glycyrrhetinic acid was observed in CYP2C9 for 4-hydroxylation of diclofenac, CYP2C19 for 4'-hydroxylation of (S)-mephenytoin and CYP3A4 for 1'-hydroxylation of midazolam with half maximal inhibitory concentration (IC50) values of 4.3-fold, 3.8-fold and 9.6-fold higher than specific inhibitors in HLM, respectively. However, glycyrrhetinic acid showed relatively little inhibitory effect (IC50>400 µm) on phenacetin O-deethylation, dextromethorphan O-demethylation and chlorzoxazone 6-hydroxylation.

CONCLUSIONS

The study indicated that CYP3A4 is likely to be the major enzyme responsible for glycyrrhetinic acid metabolism in HLM while CYP2C9 and CYP2C19 are considerably less active. The results suggest that glycyrrhetinic acid has the potential to interact with a wide range of xenobiotics or endogenous chemicals that are CYP2C9, CYP2C19 and CYP3A4 substrates.

摘要

目的

甘草次酸是甘草酸的主要代谢物，也是甘草根的主要活性成分。本研究旨在研究肝微粒体对甘草次酸的体外代谢，并研究甘草次酸可能与其他细胞色素 P450（CYP）底物发生的代谢相互作用。

方法

将甘草次酸与大鼠肝微粒体（RLM）和人肝微粒体（HLM）孵育。采用液相色谱-串联质谱法鉴定和定量分析甘草次酸或底物。

主要发现

HLM 的 K(m)和 V(max)值分别为 33.41µm 和 2.23nmol/mg 蛋白/min；RLM 的 K(m)和 V(max)值分别为 24.24µm 和 6.86nmol/mg 蛋白/min。CYP3A4 可能是 HLM 中甘草次酸代谢的主要酶，而 CYP2C9 和 CYP2C19 的活性则较低。其他人类 CYP 同工酶对甘草次酸的活性较低或没有。还研究了甘草次酸与六种 CYP 底物（如非那西汀、双氯芬酸、（S）-美芬妥因、右美沙芬、氯唑沙宗和咪达唑仑）之间的相互作用。在 CYP2C9 中观察到甘草次酸对双氯芬酸 4-羟化的抑制作用，在 CYP2C19 中观察到（S）-美芬妥因 4'-羟化的抑制作用，在 CYP3A4 中观察到咪达唑仑 1'-羟化的抑制作用，其半最大抑制浓度（IC50）值分别比 HLM 中的特异性抑制剂高 4.3 倍、3.8 倍和 9.6 倍。然而，甘草次酸对非那西汀 O-去乙基化、右美沙芬 O-去甲基化和氯唑沙宗 6-羟化的抑制作用相对较小（IC50>400µm）。