Structural elucidation of in vivo metabolites of isobavachalcone in rat by LC-ESI-MS(n) and LC-NMR.

Isobavachalcone (IBC) is a prenylated chalcone and belongs to the class of flavonoids, which is an active component isolated from Psoralea corylifolia L. IBC showed a range of significant pharmacological activities, including antibacterial, anticancer, anti-reverse transcriptase and antioxidant actions. In this research, the mass spectral fragmentation pattern of IBC was investigated to predict the in vivo metabolites, and five phase I metabolites and ten phase II metabolites of IBC in rat bile were elucidated and identified after oral administration using novel LC-ESI-MS(n) and LC-NMR method. The molecular structures of these metabolites were proposed on the basis of the characteristics of their precursor ions, product ions, MS/MS fragment behaviors and chromatographic retention time. The phase I metabolites were mainly biotransformed via the hydroxylation, reduction, cyclization and oxidative cleavage reactions. The phase II metabolites were mainly identified as the glucuronide conjugates and sulfated conjugates. All these findings were reported for the first time and would contribute to a further understanding of the in vivo intermediate processes and metabolic mechanism of isobavachalcone and its analogs.