Identification of potassium dehydroandrographolidi succinas and its major metabolites in rat urine by liquid chromatography-tandem mass spectrometry.

A rapid, sensitive and specific liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed for identification of potassium dehydroandrographolidi succinas and its metabolites in rat urine. Five male rats were administrated a single dose (100mg/kg) of potassium dehydroandrographolidi succinas by i.v. injection. The urine were sampled from 0 to 24h and purified by using Oasis® HLB extraction cartridge, then the purified urine samples were separated on a reversed-phase C18 column with a linear gradient and detected by an on-line MS detector. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular mass (Δm) and MS/MS spectra with those of the parent drug. Seven metabolites and the parent drug were found in rat urine. All these metabolites were reported for the first time.