In vivo action of alpha-amylase inhibitor from cranberry bean (Phaseolus vulgaris) in rat small intestine.

An alpha-amylase inhibitor prepared from cranberry bean (Phaseolus vulgaris) was examined for its in vivo action on pancreatic alpha-amylase in rat small intestine. For this purpose, postprandial changes not only in intraluminal alpha-amylase activity but also in plasma glucose and insulin concentrations were measured at various times after administration of 2 g of 10% polyethylene glycol-containing experimental diets with and without the inhibitor. No considerable increase was observed in the levels of intraluminal alpha-amylase activity, blood sugar, and plasma insulin in the animals given the inhibitor at a dose of 10 mg each. These results suggest that the purified preparation from cranberry bean serves in fact as a potent inhibitor of rat pancreatic alpha-amylase.