Investigating the pharmacokinetics and conjugate metabolism of potential hepatotoxic prenylflavonoids in Epimedium extract using LC-MS/MS.

This study aimed to investigate the pharmacokinetics and conjugate metabolism of four potentially hepatotoxic prenylflavonoids-sagittatoside A, icariside I, baohuoside I, and icaritin-from Epimedium extract. A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for their simultaneous quantification in rat plasma. Following oral administration of Epimedium extract at three dose levels, the plasma concentration-time curves of the four prototype flavonoids were characterized, revealing distinct pharmacokinetic profiles. Notably, icaritin exhibited a markedly delayed Tmax and a prolonged elimination half-life, consistent with enterohepatic circulation. Subsequent enzymatic hydrolysis with β-glucuronidase significantly increased the measured concentrations of all compounds, indicating extensive in vivo glucuronidation. The fold-increase in systemic exposure (AUC) post-hydrolysis varied considerably among the flavonoids and showed a dose-dependent decrease, suggesting possible saturable conjugation metabolism. This study elucidates the differential pharmacokinetic profiles of four key prenylflavonoids from Epimedium extract. The results identify icaritin as the component with the highest systemic exposure and greatest potential for accumulation, suggesting it may be a candidate contributor to Epimedium-associated hepatotoxicity. These findings provide a pharmacokinetic foundation for future toxicological investigations.