Abstract
Sophoridine is an important quinolizidine alkaloid which has wide pharmacological effect including antiarrhythmia, antitumor, immunological enhancement, and immunosuppression. In this work, a rapid, sensitive and dependable liquid chromatographic–electrospray ionization (ESI) tandem ion trap mass spectrometric method has been developed for identification of sophoridine and its metabolites in rat urine after administration of a single dose of sophoridine (12 mg/kg) by vena caudalis injection. The rat urine samples were purified by use of a C18 solid-phase extraction cartridge, then chromatographically separated by a reversed-phase C18 column (Aichrom ReliAsil C18, 5 μm, 2 mm × 150 mm i.d.) with 70:30(v/v) methanol-0.01% triethylamine solution (adjusted to pH 3.5 with formic acid) as mobile phase and detected by an on-line ESI ion trap MS-MS detector. Identification and structural elucidation of the metabolites were performed by comparing the molecular weights, retention-times, and MS-MS spectra of them with those of the parent drug. As a result, six phase I metabolites of sophoridine (N-oxide metabolite, mono-hydroxylation metabolite, hexa-dehydrogenation metabolite and three di-dehydrogenation metabolites) were identified in rat urine for the first time.
Acknowledgments
This paper was supported by National Natural Science Foundation of China (No. 30630075) and the Grant 020092325 of the Key Technology R&D Program of Science & Technology Bureau, Hubei Province, P.R. China. The authors would like to thank their colleagues for their valuable technical assistance.