Extraction and identification of polyphenols from Viburnum fordiae fruits with their α-amylase and α-glucosidase inhibitory activities

The fruits of Viburnum fordiae can be consumed both as food and for medicinal purposes, with the effect of regulating postprandial blood glucose levels. In this study, the optimised extraction and enrichment process has been utilised to produce the total polyphenols of V. fordiae fruits (VFTP), which exhibited potential α-amylase and α-glucosidase inhibitory activities. Further fractionation on VFTP led to the acquirement of two previously undescribed phenolic glycosides, vibumorsides A and B (1 and 2), along with thirteen known analogues (3–15). The structures of the new compounds were identified through comprehensive spectroscopic and chemical methods. In addition, the α-amylase and α-glucosidase inhibitory activities of these compounds were assessed. Among them, compound 2 showed the strongest inhibitory activity against α-amylase and α-glucosidase with IC50 values of 16.53 and 10.76 μM, respectively, and its molecular docking with the corresponding enzyme was also further conducted.