Rapid Identification of Berberine Metabolites in Rat Plasma by UHPLC-Q-TOF-MS

In this study, a reliable and rapid method based on ultra high performance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF-MS) technology and MetabolitePilot(MT) software was developed for berberine metabolites identification in rat plasma. The chemical structures of the metabolites and their product ions were tentatively characterized or identified according to the molecular weights detected and MS/MS data. In all, nine metabolites, including M1 (demethyleneberberine, C(19)H(18)NO(4), m/z 324), M2 (glucuronic acid-conjugated demethyleneberberine, C(25)H(26)NO(10), m/z 500), M3 (diglucuronide-conjugated demethyleneberberine, C(31)H(34)NO(16), m/z 676), M4 (glucuronic acid-conjugated jatrorrhizine or glucuronic acid-conjugated columbamine, C(26)H(28)NO(10), m/z 514), M5 (berberrubine or thalifendine, C(19)H(16)NO(4), m/z 322), M6 (glucuronic acid-conjugated berberrubine or glucuronic acid-conjugated thalifendine, C(25)H(24)NO(10), m/z 498), M7 (sulfite-conjugated berberrubine or sulfite-conjugated thalifendine, C(19)H(16)NO(7)S, m/z 402), M8 (dihydroxy berberrubine or dihydroxy thalifendine, C(19)H(16)NO(6), m/z 354) and M9 (dihydroxy berberine, C(20)H(18)NO(6), m/z 368) were tentatively characterized or identified. Several new deposition patterns and three new metabolites (M7, M8 and M9) are reported in this paper for the first time. This work not only provides significant insights into the understanding of the metabolic pathways of berberine, but also contributes in identifying potential active drug candidates from the metabolites.