Metabolic profiling of icariin in rat feces, urine, bile and plasma after oral administration using ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry
Icariin, the major flavonoid constituent of the traditional Chinese medicine Epimedii Folium, is extensively researched owing to its comprehensive beneficial effects. This study aimed at identifying the in vivo metabolites and the metabolic profiling in rats after oral administration at a dose of icariin (100 mg/kg) with the aid of an ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS/MS) and metabolynx™ software. A total of 25 metabolites were detected and 4 of them were compared with standard substances. Among them, 10 metabolites were reported for the first time. The results indicated that the principal metabolism pathways of icariin in rat were hydroxylation and the conjugation with glucuronide. It also confirmed that M2, M14, M18 and M23 were the major circulating forms of icariin in rats following oral administration. Demethylation, dehydrogenation, epoxidation, reduction, oxidation were also observed and the epoxidation and reduction on the isopentenyl were regarded as new metabolic patterns of icariin. Moreover, this study could enrich the understanding of the metabolism of icariin and help to elucidate the metabolic profiling of other prenylflavonoids.