Identification of three sulfate-conjugated metabolites of berberine chloride in healthy volunteers' urine after oral administration

AIM: To identify the structure of unknown metabolites of berberine (Ber) in human urine after oral administration. METHODS : Urine samples were obtained from 5 volunteers after they orally took Ber chloride 0.9 g per day for three days. Metabolites in urine samples were isolated and purified by polyporous resin column chromatography. The individual metabolites were identified mainly using electrospray ionization mass spectroscopy (ESI-MS) and proton nuclear magnetic resonance (H-1 NMR) spectroscopy. RESULTS: Three unknown metabolites (M1, M2, and M3) were isolated. They were susceptible to arylsufatase. ESI-MS measurements of M1, M2, and M3 produced quasimolecular ions [M + H](+), m/z 417.9, 404.0, and 402.0 respectively. Especially, each of them produced a characteristic protonated ion [M-80 + H](+), which can be ascribed as quasimolecular ions lost a SO3 fragment. H-1 NMR spectra of the metabolites were also obtained and each of H-1 signals was assigned. CONCLUSION: Structures of M1, M2, and M3 were firmly identified as jatrorrhizine-3-sulfate, demethyleneberberine-2-sulfate, and thalifendine-10-sulfate, and the major metabolite was M2.