Comprehensive metabolism study of swertiamarin in rats using ultra high-performance liquid chromatography coupled with Quadrupole-Exactive Orbitrap mass spectrometry

Abstract

Swertiamarin, a natural ingredient with potent pharmacological activities in the iridoid glycoside family, had been reported to have significant therapeutic effects on a variety of human diseases. In this study, a systematic and efficient strategy based on UHPLC-Q-Exactive Orbitrap mass spectrometry was established to reveal the metabolic profile of swertiamarin in rat urine, plasma, and faeces. First of all, post-acquisition data-mining methods, including multiple mass defect filters (MMDFs) and high-resolution extracted ion chromatograms (HREICs), were developed to screen the metabolite candidates of swertiamarin from the complete mass scan data sets. Second, according to the diagnostic product ions (DPIs), neutral loss fragments (NLFs), chromatographic retention time, accurate mass measurement and calculated Clog P values, all metabolite candidates were rapidly identified. As a consequence, 49 metabolites altogether, including archetype compound, were preliminarily characterised. The corresponding in vivo biotransformation processes, such as dehydration, dehydrogenation, hydroxylation, hydrogenation, methylation, sulphonation, N-acetylcysteine (NAC) formation, N-heterocyclisation and their composite reactions, were all discovered in the study. In conclusion, our results not only detailedly elucidated many new metabolites and metabolic pathways of swertiamarin, but also provided a reference for further study of its pharmacological mechanism and evaluation of its safety.