Metabolism of Rhizoma coptidis in Human Urine by Ultra-High-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry.

BACKGROUND AND OBJECTIVES: Rhizoma coptidis extract and its alkaloids were reported to exhibit various pharmacological activities. However, pharmacokinetics investigations indicated that the plasma concentrations of the alkaloids were too low to explain their systemic therapeutic actions. Thus, the metabolic profile of Rhizoma coptidis in humans is yet to be fully investigated and the present study aimed to investigate the metabolic profile of Rhizoma coptidis in human urine after oral administration of Rhizoma coptidis extract. METHODS: In this study, the metabolism of Rhizoma coptidis at a clinical dose (5 g/60 kg/day) was investigated using ultra-high-performance liquid chromatography coupled with high-resolution LTQ-Orbitrap mass spectrometry. RESULTS: Totally, 30 constituents including 7 prototypes, 5 sulfation metabolites and 18 glucuronide conjugates were elucidated and identified on the basis of the characteristics of their high-resolution precursor ions, product ions, and chromatographic retention times in human urine. Among the 7 prototypes, 3 prototypes (M20, M26 and M28) were identified definitely by comparing with standards. Based on the metabolites detected in human urine, a possible metabolic pathway of Rhizoma coptidis in vivo was proposed. CONCLUSIONS: The results demonstrated that the metabolic fate of Rhizoma coptidis mainly involved sulfation and glucuronidation in human urine and the glucuronide conjugate M14 (berberrubinen-9-O-glucuronide) might be a pharmacokinetic marker for Rhizoma coptidis alkaloids in humans. This study will be helpful to comprehensively understand the metabolic process of Rhizoma coptidis and how Rhizoma coptidis shows its pharmacological effects in humans.

Metabolic profile of Rhizoma coptidis in human plasma determined using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry.

RATIONALE: Rhizoma coptidis extract and its alkaloids show various pharmacological activities, but its metabolic profile in human plasma has not been thoroughly investigated. In the present research, the metabolism of Rhizoma coptidis at a clinical dose (5 g/60 kg/day) was systematically analyzed to determine its biotransformation processes in human plasma. METHODS: In this research, the metabolites of Rhizoma coptidis in human plasma after oral administration of Rhizoma coptidis extract at a clinical dose were investigated using ultra-high-performance liquid chromatography (UHPLC) coupled with high-resolution LTQ-Orbitrap mass spectrometry. The structural elucidation of the constituents was confirmed by comparing their retention times (tR ) and MSn fragments with those of standards and literature reports. RESULTS: In total, two prototypes and twelve metabolites were detected in human plasma. The two prototypes were confidently identified using reference standards. Of the compounds detected, M7 (berberrubinen-9-O-glucuronide) was the most abundant based on its peak area, which indicates that this compound might be a pharmacokinetic marker for Rhizoma coptidis alkaloids in humans. Based on the metabolites detected in human plasma, a possible metabolic pathway for Rhizoma coptidis in vivo was proposed. CONCLUSIONS: The results indicated that the alkaloids in Rhizoma coptidis were extensively biotransformed in vivo mainly via conjugation with glucuronic acid (GluA) or sulfuric acid (SulA) to form phase II metabolites, and the GluA metabolites are likely the dominant form in human plasma. To the best of our knowledge, this is the first in vivo evaluation of the metabolic profile of the whole Rhizoma coptidis extract in human plasma, which is essential for determining the chemicals responsible for the pharmacological activities of Rhizoma coptidis in vivo. Moreover, it would be beneficial for us to further systematically study the pharmacokinetic behavior of Rhizoma coptidis in humans.