Pharmacokinetics and metabolic profiles of swertiamarin in rats by liquid chromatography combined with electrospray ionization tandem mass spectrometry.

Swertiamarin, a typical compound of secoiridiod glycosides with various pharmacological effects which is the major iridoid glicoside of Swertia. In this study, we have established a fast and sensitive LC-MS/MS method. The aim was to conduct pharmacokinetic studies of swertiamarin in vivo of rats. Gentiopicroside was used as internal standard and a C18 column was employed for the separation of analytes. The selected reaction monitoring transitions were m/z 375→177, 357.1→195 for swertiamarin and the internal standard, respectively, in a positive ion mode. The results showed that swertiamarin had a good linearity in the range of 2-8000 ng/mL (r ＞ 0.997) and its limit of detection (LLOD) was 0.5 ng/mL. The developed method subsequently successfully used in the pharmacokinetic study of swertiamarin in rats after oral administration (50, 100, and 150 mg/kg). We obtained a series of pharmacokinetic parameters, and the half-time of swertiamarin was 1 h, while the oral bioavailability was between 5.6-7.6%. Six metabolites of swertiamarin were identified based on accurate mass measurements of protonated molecules and their MS/MS spectrum by ultra-high-performance chromatography/tandem quadrupole time-of-flight mass spectrometry. Furthermore, metabolites were classified into three groups and the metabolic pathway of swertiamarin was proposed. The finding may help for the understanding of effectiveness and safety of swertiamarin.