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Ganoderic Acid A Metabolites and Their Metabolic Kinetics
Fang-Rui Cao1, Li Feng1, Lin-Hu Ye1
1Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing, China.
Frontiers in Pharmacology
|March 23, 2017
Summary
Ganoderic acid A (GAA) undergoes extensive metabolism in rats, producing 37 identified metabolites. Key metabolites Ganoderic acid C2 and a dihydroxy-trioxo-lanost-oic acid exhibit hyperbolic kinetics, primarily metabolized by CYP3A.
Area of Science:
- Pharmacokinetics and Drug Metabolism
- Natural Product Chemistry
- Triterpenoid Metabolism
Background:
- Ganoderma lucidum triterpenoids, including Ganoderic acid A (GAA), possess diverse bioactivities.
- Understanding the metabolism of GAA is crucial for its therapeutic applications.
- Previous studies have not comprehensively elucidated GAA's metabolic pathways and kinetics.
Purpose of the Study:
- To identify Ganoderic acid A (GAA) metabolites in vivo (rats) and in vitro (liver microsomes).
- To investigate the metabolic kinetics of major GAA metabolites.
- To identify the specific cytochrome P450 isoenzyme responsible for GAA biotransformation.
Main Methods:
- Intravenous administration of GAA to rats, followed by analysis of bile, plasma, and urine.
- In vitro incubation of GAA with rat liver microsomes (RLMs) and human liver microsomes (HLMs).
- High-Performance Liquid Chromatography-Diode Array Detection-Mass Spectrometry/Mass Spectrometry (HPLC-DAD-MS/MS) for metabolite identification and quantification.
- Kinetic analysis of major metabolites using established pharmacokinetic models.
Main Results:
- A total of 37 GAA metabolites were tentatively identified in vivo, with similar metabolites found in vitro.
- GAA undergoes extensive Phase I and Phase II metabolism, with specific carbonyl and carbon atoms identified as metabolic soft spots.
- Ganoderic acid C2 (GAC2) and 7β,15-dihydroxy-3,11,23-trioxo-lanost-26-oic acid were identified as major reduction metabolites.
- The kinetics of GAC2 and the dihydroxy-trioxo-lanost-oic acid followed classical hyperbolic kinetics.
- Cytochrome P450 3A (CYP3A) was identified as the primary isoenzyme responsible for the biotransformation of these key metabolites in both RLMs and HLMs.
Conclusions:
- This study provides the first comprehensive analysis of Ganoderic acid A (GAA) metabolism in vivo and in vitro.
- The identified metabolites and metabolic pathways offer insights into GAA's pharmacokinetic profile.
- The characterization of metabolic kinetics and the involvement of CYP3A are critical for understanding GAA's drug interactions and therapeutic potential.
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