Fundamental studies on the inhibitory action of Acanthopanax senticosus Harms on glucose absorption

Aim of the studyAcanthopanax senticosus Harms extract (ASE) is used as an ingredient of over-the-counter drugs and functional foods, such as health supplements, in Japan. ASE exhibits a hypoglycemic effect; however, the mechanism of the hypoglycemic effect is not clear. In the present study, we investigated whether ASE has a glucose absorption inhibitory action.Materials and methodsWe examined the effects of ASE on α-amylase and α-glucosidase activities, and on glucose uptake in Caco-2 cells. We also examined the effects of ASE oral administration on glucose tolerance in type 2 diabetes mellitus model db/db mice.ResultsThe addition of ASE inhibited α-glucosidase activity but not α-amylase activity. The α-glucosidase inhibitory activity of ASE was approximately 1/13 of that of acarbose. The addition of ASE inhibited 2′-deoxy-d-glucose (DG) uptake in human intestinal Caco-2 cells, and the inhibitory activity of ASE was approximately 1/40 of that of phloretin. Kinetic analysis of glucose uptake indicated that ASE has no effects on DG uptake through passive diffusion, but that ASE inhibits intracellular DG uptake chiefly by inhibiting transport via a glucose transporter. In the glucose tolerance study, db/db mice orally administered ASE for 3 days showed significantly lower plasma glucose level than the control group 30 min after sucrose loading, without affecting plasma insulin levels. In addition, ASE oral administration significantly inhibited α-glucosidase activity in the small intestine mucosa extirpated from the mice.ConclusionThese findings indicate that ASE may be useful as an ingredient of functional foods to improve postprandial hyperglycemia and prevent type II diabetes mellitus.

Graphical abstractAcanthopanax senticosus Harms extract (ASE) suppressed glucide absorption by the inhibition of intestinal α-glucosidase activity and glucose uptake. ASE is expected to inhibit the rapid rise in blood glucose level immediately after a meal and to improve impaired glucose tolerance in type II diabetes mellitus.Figure optionsDownload full-size imageDownload as PowerPoint slide