Related Experiment Video
Updated: Aug 11, 2026

Mass Spectrometry and Luminogenic-based Approaches to Characterize Phase I Metabolic Competency of In Vitro Cell Cultures
Published on: March 28, 2017
Inhibition of human cytochrome P450 isoforms and NADPH-CYP reductase in vitro by 15 herbal medicines, including
1Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine and Clinical Pharmacology Center, #633-165 Gaegum-Dong, Busanjin-Gu, Busan Paik Hospital, Busan 614-735, South Korea.
Objective:
We evaluated the potential of 15 herbal medicines (HMs), commonly used in Korea, to inhibit the catalytic activities of several cytochrome P450 (CYP) isoforms and microsomal NADPH-CYP reductase.
Methods:
The abilities of 1-1000 microg/mL of freeze-dried aqueous extracts of 15 HMs to inhibit phenacetin O-deethylation (CYP1A2), tolbutamide 4-methylhydroxylation (CYP2C9), S-mephenytoin 4'-hydroxylation (CYP2C19), dextromethorphan O-demethylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1), midazolam 1-hydroxylation (CYP3A4) and NADPH-CYP reductase were tested using human liver microsomes.
Results:
The HMs Epimedii herba, Glycyrrhizae radix and Leonuri herba inhibited one or more of the CYP isoforms or NADPH-CYP reductase. Of the three HMs, Epimedii herba extracts were the most potent inhibitors of several CYP isoforms (IC(50) 67.5 microg/mL for CYP2C19, 104.8 microg/mL for CYP2E1, 110.9 microg/mL for CYP2C9, 121.9 microg/mL for CYP3A4, 157.8 microg/mL for CYP2D6 and 168.7 microg/mL for CYP1A2) and NADPH-CYP reductase (IC(50) 185.9 microg/mL ).
Conclusion:
These results suggest that some of the HMs used in Korea have the potential to inhibit CYP isoforms in vitro. Although the plasma concentrations of the active constituents of the HMs were not determined, some herbs could cause clinically significant interactions because the usual doses of those individual herbs are several grams of freeze-dried extracts. Controlled trials to test the significance of these results are necessary.
Related Concept Videos
Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes
Pharmacokinetics: Drug–Drug Interactions
Effect of Hepatic Disease on Pharmacokinetics: Dose Adjustments Due to Hepatic Impairment
Pharmacokinetics: Drug–Food and Drug–Viral Interactions
Pharmacokinetics in Geriatric Patients: Effect of Age on Drug Metabolism
Drug toxicity: Idiosyncratic Reactions
