Screening and identification of multiple constituents and their metabolites of Fangji Huangqi Tang in rats by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry basing on coupling data processing t

• Novel constituents identification strategy coupling data processing techniques.
• First report on description of fangchinoline and tetrandrine metabolism in vivo.
• Rapid and reliable mode for constituents and their metabolites searching of TCM.

Fangji Huangqi Tang (FHT) is a classical formula widely used in Chinese clinical application. In this paper, a novel and advanced strategy has been developed for the multiple constituent identification of FHT in rats, which was basing on an ultra-high performance liquid chromatography equipped with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS) method combined with dynamic background subtract (DBS) data acquisition and enhance peak list (EPL) data processing techniques. Firstly, a total of 58 potential bioactive compounds including alkaloids, flavonoids, saponins, saccharides and terpenoids were detected from FHT. Their chemical structures were identified by comparing the retention time and mass spectrometry data, as well as retrieving the reference literatures. Based on the same instrumental conditions, 33 compounds were found in rat serum after oral administration of FHT. After a considerate comparison with the former chemical identification results of FHT, 33 compounds were found, which turned out to be 8 original compounds of FHT as well as 25 metabolites, including 20 phase I and 5 phase II metabolites. The results indicated that the metabolic reactions included hydroxylation, hydrogenation, demethylation, tarine conjugation and acetylation. This study firstly reported the metabolism description of fangchinoline and tetrandrine in vivo, which could be very useful for further pharmacological and clinical studies of FHT. Meanwhile, it provided a practical strategy for rapid screening and identifying of multiple constituents and their metabolites of complex traditional Chinese medicine in biological matrix.