Tentative identification of new metabolites of cnidilin by liquid chromatography-mass spectrometry.

Cnidilin is one of the major bioactive constituents of Radix Angelicae dahuricae. The present study was designed to characterize and interpret the structures of metabolites in rats after oral administration of cnidilin at a dose of 48mg/kg body weight. Metabolite identification was accomplished using a predictive multiple reaction monitoring-information-dependent acquisition-enhanced product ion (pMRM-IDA-EPI) scan and precursor ion scan-information-dependent acquisition-enhanced product ion (PREC-IDA-EPI) scan in positive ion mode. Comparing the changes in protonated molecular masses, MS/MS spectra and retention times with the parent drug, 18 metabolites were identified. The result shows that the metabolic pathways contain deisopentenyl, combination with glucose, hydroxylation, oxidation, demethylation and addition reaction. The study identified 18 metabolites, analyzed and summarized the fragmentation regularities of mass spectra of 8-methoxy-5-hydroxy psoralen. The study provides a new pathway to discovery new compounds, new fragmentation regularities and the mode of metabolites.