Background: Calycosin (CAL), a type of O-methylated isoflavone extracted from the herb Astralagusmembranaceus  (AM), is a bioactive chemical with antioxidative, antiphlogistic and antineoplastic activities commonly used in traditional alternative Chinese medicine. AM has been shown to confer health benefits as an adjuvant in the treatment of a variety of diseases.
Aim: The main objective of this study was to determine whether CAL influences the cytochrome P450 (CYP450) system involved in drug metabolism.
Methods: Midazolam, tolbutamide, omeprazole, metoprolol and phenacetin were selected as probe drugs. Rats were randomly divided into three groups, specifically, 5% Carboxymethyl cellulose (CMC) for 8 days (Control), 5% CMC for 7 days + CAL for 1 day (single CAL) and CAL for 8 days (conc CAL), and metabolism of the five probe drugs evaluated using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).
Results: No significant differences were observed for omeprazole and midazolam, compared to the control group. T _max and t_1/2 values of only one probe drug, phenacetin, in the conc CAL group were significantly different from those of the control group (T _max h: 0.50± 0.00 vs 0.23± 0.15; control vs conc CAL). C _max of tolbutamide was decreased about two-fold in the conc CAL treatment group (conc vs control: 219.48 vs 429.56, P < 0.001).
Conclusion: Calycosin inhibits the catalytic activities of CYP1A2, CYP2D6 and CYP2C9. Accordingly, we recommend caution, particularly when combining CAL as a modality therapy with drugs metabolized by CYP1A2, CYP2D6 and CYP2C9, to reduce the potential risks of drug accumulation or ineffective treatment.
Keywords: calycosin, herb-drug interactions, UPLC-MS/MS, cocktail, CYP450