Metabolic profile of esculin in rats by ultra high performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry

Esculin, a coumarin derivative found in Fraxinus rhynchophylla, has been reported to possess multiple biological activities. This present study is designed to investigate the metabolic profile of esculin in vivo based on ultra high performance liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (UHPLC-FT-ICR-MS) for the first time. After oral administration of esculin (100 mg/kg) for rats, plasma, urine, feces and bile samples were collected to screen metabolites. As a result, a total of 19 metabolites (10 phase I metabolites and 9 phase II metabolites) were found and identified. Results showed that metabolic pathways of esculin included hydrolysis, dehydrogenation, hydroxylation, methylation, dehydrogenation, glucuronidation, sulfation, and glycine conjugation. It was also found that after oral administration of esculin, the esculin could be metabolized to esculetin in vivo via deglycosylation, and esculetin was found in all biological samples. This study also laid solid basis for in-depth development of esculin and provided important information for clarifying the biotransformation process of esculin in vivo.