Preliminary identification of the absorbed bioactive components and metabolites in rat plasma after oral administration of Shaoyao-Gancao decoction by ultra-performance liquid chromatography with electrospray ionization tandem mass spectrometry

Shaoyao-Gancao decoction (SGD), a traditional Chinese medicine formula, has been used for the treatment of abdominal pain and dysmenorrhea disease in Asia over long period of time. Its effectiveness has been confirmed in clinic, but its active constituents remain unclear.In this paper, a rapid, sensitive and reliable ultra-performance liquid chromatography-electrospray ionization/quadrupole-time-of-flight high-definition mass spectrometry (UPLC-ESI-Q-TOF-MS) in positive and negative ion mode were established to characterize the active constituents of SGD in vitro. The analysis was performed on a Waters UPLCTM HSS T3 (2.1 × 100 mm, 1.8 µm) using gradient elution system. Automated MetaboLynxTM technique was employed to screen for the potentially bioactive components in rat plasma after oral administration of SGD. MS/MS fragmentation behavior was proposed for aiding the structural identification of the components.Based on the developed method of fingerprint analysis, an injection run of the plasma sample was finished in 15.0 min. A total of 12 compounds including 9 prototype components such as gallicacid, albiflorin, liquiritin, pallidiflorin, liquiritigenin, isoLiquiritigenin, formononetin, isolicoflavonol, licoricone, C9H10O3 and 2 metabolites such as liquiritigenin-4'-O-glucuronide, formononetin glucuronide were identified or tentatively characterized. Of note, 3 ingredients were identified from Radix Paeoniae Alba, and 9 were from Radix Glycyrrhizae.The compounds found in dosed plasma could be the effective substances of SGT for treating dysmenorrheal, and may provide important experimental data for further pharmacological and clinical research of SGD. Furthermore, this work has demonstrated that the feasibility of the UPLC-ESI-Q-TOF-MS for rapid and reliable characterization of identification and structural elucidation of the chemical constituents and their metabolites from herbal medicines.