Inhibitory effects on α-glucosidase and hypoglycemic effects of the crude polysaccharides isolated from 11 edible fungi

This objective of this study was to investigate the inhibitory effect of polysaccharides extracted from 11 edible fungi on α-glucosidase in vitro and their hypoglycemic effect in type 2 diabetic mellitus (DM) mice. In vitro, α-glucosidase activity was determined by measuring the p-nitrophenol released from p-Nitrophenyl-α-D-Glucopyranoside at 400 nm. In vivo,Kunming mice with steptozotocin-induced combination high fat diet fed were used. At the end of the study, blood serum glucose and insulin of the mice were measured. In vitro, the crude polysaccharides of Phellinus igniarius and Phellinus chrysoloma showed strong α-glucosidase inhibitory activities of 79.72 and 89.26 %, respectively. In vivo, Serum glucose levels significantly differed (P < 0.01) between the polysaccharides dose-treated groups and the DM group. Grifola frondosa crude polysaccharides showed the greatest hypoglycemic effect in lowering the diabetic blood serum glucose level by 50.09%. The crude polysaccharides of Ganaderma lucidum, Ganaderma sinense, G. frondosa, P. igniarius and P. chrysoloma significantly increased the insulin sensitivity index (ISI) compared with the DM group (P < 0.05). The crude polysaccharides of P. igniarius and P. chrysoloma demonstrated high α-glucosidase inhibitory activities. All 11 edible fungi polysaccharides significantly decreased the fasting serum glucose level in type 2 DM mice. Furthermore, G. lucidum, G. sinense, G. frondosa, P. igniarius and P. chrysoloma crude polysaccharides were able tofacilicate the utilization of insulin and improve insulin resistance.   Key words: Edible fungi, polysaccharides, hypoglycemic activity, type 2 diabetes mellitus mice, α-glucosidase inhibitory activity.