Abstract: Crude polyphenols were extracted with ethanol from the pericarps of Zanthoxylum bungeanum and fractionated by sequential solvent extraction with dichloromethane (F1), ethyl acetate (F2), n-butanol (F3) and water (F4). The phenolic composition in these fractions were identified and quantified using ultra-high performance liquid chromatography-electrospray ionization-quadrupole-time of flight-tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS). Their α-glucosidase inhibitory effect and hypoglycemic activity in mice with type II diabetes mellitus were examined. Results demonstrated that 20 phenolic compounds were identified in the pericarps of Z. bungeanum, including nine phenolic acids and their derivatives, and 11 flavonoid compounds. The contents of total phenols, total flavonoids and polyphenols in the four fractions decreased in the following order: F2 > F3 > F4 > F1, indicating that fractional extraction can effectively enrich polyphenols. Polyphenols from Z. bungeanum pericarps had inhibitory effect on α-glucosidase, and F3 gave the highest percentage of inhibition (85.86%). The inhibition of α-glucosidase activity was found to be uncompetitive. The major bioactive components in F3, chlorogenic acid and rutin, were significantly positively correlated with the percentage of α-glucosidase inhibition. Additionally, F3 could reduce fasting blood glucose level and oral glucose tolerance in diabetic mice by 64.2% and 21.42%, respectively, and improve abnormal body mass and diet in diabetic mice. Therefore, polyphenols from Z. bungeanum pericarps have the potential for use as a therapeutic agent for the prevention and treatment of diabetes.

Key words: Zanthoxylum bungeanum pericarps; polyphenols; chemical constituents; hypoglycemic activity