Identfication of phase I and phase II metabolites of hesperetin in rat liver microsomes by liquid chromatography-electrospray ionization-tandem mass spectrometry.

The purpose of this study is to investigate the in vitro metabolism of hesperetin, a bioflavonoid. Hesperetin was incubatedwith rat liver microsomes in the presence of NADPH and UDP-glucuronic acid for 30 min. The reaction mixture was analyzedby liquid chromatography-ion trap mass spectrometer and the chemical structures of hesperetin metabolites were characterzed basedon their MS/MS spectra. As a result, a total of five metabolites were detected in rat liver microsomes. The metabolites were identifiedas a de-methylated metabolite (eriodictyol), two hesperetin glucuronides, and two eriodictyol glucuronides.