CYP3A catalyses schizandrin biotransformation in human, minipig and rat liver microsomes

Abstract

1. Schizandrin is recognized as the major absorbed effective constituent of Fructus schisandrae, which is extensively applied in Chinese medicinal formula. The present study aimed to profile the phase I metabolites of schizandrin and identify the cytochrome P450 (CYP) isoforms involved.

2. After schizandrin was incubated with human liver microsomes, three metabolites were isolated by high-performance liquid chromatography (HPLC) and their structures were identified to be 8(R)-hydroxyl-schizandrin, 2-demethyl-8(R)-hydroxyl-schizandrin, 3-demethyl-8(R)-hydroxyl-schizandrin, by liquid chromatography-mass spectrometry (LC-MS), ¹H-nuclear magnetic resonance (NMR), and ¹³C-NMR, respectively. A combination of correlation analysis, chemical inhibition studies, assays with recombinant CYPs, and enzyme kinetics indicated that CYP3A4 was the main hepatic isoform that cleared schizandrin. Rat and minipig liver microsomes were included when evaluating species differences, and the results showed little difference among the species.

3. In conclusion, CYP3A4 plays a major role in the biotransformation of schizandrin in human liver microsomes. Minipig and rat could be surrogate models for man in schizandrin pharmacokinetic studies. Better knowledge of schizandrin’s metabolic pathway could provide the vital information for understanding the pharmacokinetic behaviours of schizandrin contained in Chinese medicinal formula.

Keywords::

• Schizandrin
• cytochrome P450
• microsomes
• metabolism
• Fructus schisandrae

Acknowledgements

This work was supported by the 973 Program (Grant Number 2009CB522808) of the Ministry of Science and Technology of China, the National Key Technology R&D Program in the 11th Five Year Plan of China (Grant Number 2008ZX10208), the National Natural Science Foundation of China (Grant Numbers 30772608 and 30973590), and the Dalian Institute of Chemical Physics Innovation Fund of Chinese Academy of Sciences.

Declaration of interest: The authors state no conflicts of interest. The authors alone are responsible for the content and writing of the paper.