Characterization of metabolic profiles of Lanqin Oral Liquid in rats by ultra-high-performance liquid chromatography tandem time-of-flight mass spectrometry

Objective: Lanqin oral liquid (LOL), as a traditional Chinese medicine prescription, has obvious clinical efficacy in the treatment of pharyngeal inflammation. Exploring the distribution of LOL prototype components and metabolites in plasma is of great significance for understanding potentially effective compounds. The aim of this study is to elucidate the metabolites and main metabolic pathways of LQL in vivo. Methods: In this study, a reliable approach integrated background subtraction and mass defect filtering (MDF), based on quadrupole time-of-flight mass spectrometry (QTOF-MS) technology, was performed to systematically scan the metabolites of LOL in rat plasma. In addition, according to the prototype mass spectrometry fragmentation pattern and combined with metabolic pathway analysis, a biotransformation oriented analysis strategy was established and applied to the identification of metabolites in LOL in vivo. Results: As a result, 159 compounds (58 prototypes and 101 metabolites) were identified or tentatively characterized in drug-containing plasma, including 74 flavonoids, 30 alkaloids, 34 terpenoids, five phenylpropanoids, six phenolic acids, five fatty acids, and five other type components. The main metabolic pathways include methylation, demethylation, hydroxylation, hydrogenation, glucuronidation, and sulfation. Conclusions: This study provides an overall characterization of the metabolites of LOL in vivo for the first time, providing a solid material basis for exploring the therapeutic effects and pharmacological mechanisms of LOL.