Plant Secondary Metabolites with α-Glucosidase Inhibitory Activity

Plant-derived compounds with α-glucosidase inhibitory activity reported in the past four decades were summarized, mainly covering flavonoids, N-containing compounds, and terpenoids. Among these inhibitors, eighty-eight flavonoids account for the majority, and N-containing compounds including eleven aromatic amides, 1-deoxynojirimycin (DNJ), and 16 derivatives or structural analogues of DNJ, which are members of polyhydroxylated piperidine or pyrrolidine alkaloids, or polyhydroxy-nor-tropane alkaloids, are the second largest group and have the most specific structures, and twelve terpenoids without glycosylation have also been reported to show inhibitory activity. The plant sources and reported IC50 values of these inhibitors are presented in tables, and their structure characteristics and isolation methods are also briefly summarized. Medicinal plants are proved to be important and potential sources to discover α-glucosidase inhibitors. Whereas, low content and time-consuming extraction limit the application of plant-derived α-glucosidase inhibitors in the treatment of diabetes. Chemical modification and SAR study of natural α-glucosidase inhibitors are of importance, and standard plant extracts have potential use for the future prevention and treatment of diabetes.