α-Glucosidase Inhibitory Activity-guided Identification of Compounds from Clerodendrum bungei Steud by HPLC-ESI- QTOF-MS/MS

Objective: To identify the compounds with α-glucosidase inhibitory activity from Clerodendrum bungei Steud (Chou Mu Dan, 臭牡丹) using HPLC-ESI-QTOF-MS/MS. Methods: The ethanol extracts of Clerodendrum bungei Steud (Chou Mu Dan, 臭牡丹) were partitioned with petroleum ether, ethyl acetate, n-butanol, and water. The assay for α-glucosidase inhibitory activity revealed strong α-glucosidase inhibitory activity in the ethyl acetate fraction, and the bioactive compounds present in this fraction were identified by the HPLC- ESI-QTOF-MS/MS method. Results: A total of 29 compounds were determined, among the identified bioactive components; these included 12 phenylethanoid glycosides (compounds 5, 6, 12-17, 20-22, 24), 7 flavonoids (compounds 10, 19, 23, 25-28), 5 phenolic acids (compounds 2-4, 7, 9), and 5 other compounds. Compounds 2-4, 7, 9-10, 12-13, 15, 19, and 26, with a potential α-glucosidase inhibitory activity, have been reported previously. Conclusions: Our results show that the methodology used in this study is feasible, credible, and rapid in identifying known compounds and also for characterizing new natural α- glucosidase inhibitory candidates from Clerodendrum bungei Steud (Chou Mu Dan, 臭牡丹). Keywords: α-glucosidase inhibitor, Clerodendrum bungei Steud (Chou Mu Dan, 臭, 牡,丹), HPLC-ESI-QTOF-MS/MS