An LC-MS/MS method for simultaneous quantification of six components of <i>Angelicae pubescentis radix</i> and systematic evaluation of <i>Angelicae pubescentis radix</i> as a potential inhibitor of multiple cytochrome P450 enzymes

1. Quantitative analytical method was developed for six coumarin constituents in Angelicae pubescentis radix (APR), and the inhibitory effect of the herb's extract on cytochrome P450 enzymes was investigated.2. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of six coumarins (imperatorin, 8-methoxypsoralen, isopimpinellin, isoimperatorin, bergapten, and cnidilin) in APR. Concurrently, the inhibitory effects of its aqueous extract on multiple P450s were evaluated in rat liver microsomes using a 'Pittsburgh cocktail' approach.3. The method demonstrated excellent linearity (R2 > 0.999), precision, stability, repeatability (RSD < 3.0%), and recovery (95.15-102.36%). The extract exhibited significant time-dependent inhibition of CYP1A2 (residual activity 58.2%), with weaker effects on other P450s.4. A robust LC-MS/MS method was successfully established. The extract of APR was identified as a potent time-dependent inhibitor of CYP1A2 in rat liver microsomes (RLMs), suggesting a potential risk for metabolism-based drug interactions in rats that warrants further investigation in human systems.