Evaluation of the effects of paeoniflorin on cytochrome P450 isozymes in rats

1. This study aims to investigate the effects of orally administered paeoniflorin (PF), a major bioactive compound from Paeonia lactiflora, on cytochrome P450 (CYP450) enzyme activity in rats to assess potential drug-drug interactions (DDIs). Following PF treatment, rats received a mixed probe drug solution containing phenacetin (PHE), tolbutamide (TOL), omeprazole, and metoprolol, and plasma concentrations of the substrates and metabolites were quantified using ultra-high-performance liquid chromatography-tandem mass spectrometry. The metabolic ratio, calculated as the ratio of metabolite to parent drug area under the curve (AUC), was used to evaluate CYP activity.2. Results showed that AUCAcetaminophen/AUCPHE values were significantly elevated in PF-treated groups, indicating induction of CYP1A2, whereas AUCOHTOL/AUCTOL values were significantly reduced, suggesting inhibition of CYP2C11. No significant effects were observed on CYP2C or CYP2D2 activities.3. These findings indicate that PF can modulate CYP1A2 and CYP2C11 activities under the experimental conditions tested, as assessed using PHE and TOL as functional markers. However, the magnitude of these effects was modest and observed only at relatively high PF doses (50 and 100 mg/kg). Given the inherent species differences between rat and human CYP enzymes, direct extrapolation of these findings to human CYP1A2 and CYP2C11 requires further validation in human-relevant models.