ETHNOPHARMACOLOGICAL RELEVANCEBuyang Huanwu Decoction (BYHWD), a traditional Chinese medicine, is one of the classic prescriptions for the treatment of ischemic stroke in clinical practice. It has the effects of tonifying qi, activating blood circulation, and promoting meridian circulation. However, its chemical analysis has not been clarified, which greatly hinders its further clinical application. Therefore, it is necessary to clarify the chemical constituents and metabolites profile of BYHWD in vivo.AIM OF THE STUDYCharacterizing the chemical basis of BYHWD in vitro, and combing studies of related metabolism in vivo to screen out the potential active components of BYHWD with pharmacological effects in vivo.MATERIALS AND METHODSTwelve male rats weighed 200 ± 20 each were selected for the experiments. According to the fragmentation of different structural types of components and diagnostic ions, UHPLC-Q-TOF-MS/MS was used to classify and clarify the unknown components of BYHWD and identify the material basis of BYHWD in vitro. Then, rat plasma, tissues, feces, and urine were collected for analysis. Based on the similarity of MS responses (accurate molecular weight and secondary fragmentation) and chromatographic behavior (retention time), the in vivo prototype and metabolites were analyzed. Through the phase I and phase II metabolism law, a metabolite library was established to analyze the prototype-matched metabolites.RESULTSA total of 121 in vitro compounds and 55 in vivo prototypes of BYHWD were identified, corresponding to 123 matched prototypes. It was mainly composed of flavonoids, triterpene saponins, nucleosides and lactones both in vitro and in vivo. Quercetin, ligustilide, astragaloside IV, calycosin, paeoniflorin and ferulic acid were the main prototypes and metabolites in plasma and urine.CONCLUSIONQuercetin, ligustilide, astragaloside IV, calycosin, paeoniflorin and ferulic acid were the main active ingredients of BYHWD.