2004 Volume 50 Issue 3 Pages 161-164
We examined the inhibitory effects of aqueous ethanol extract from mulberry leaves (ME) on postprandial hyperglycemia in normal Wistar rats. ME dose-dependently suppressed the postprandial rise of blood glucose in rats, when ME (0.02-0.5g/kg) was given 0.5h before the administration of carbohydrates such as sucrose, maltose and starch. The ME dose showing 50% inhibition of the increment of blood glucose (ED50) was 0.11g/kg for sucrose, 0.44g/kg for maltose, and 0.38g/kg for starch. ME and its basic fraction (MB) containing 1-deoxynojirimycin were assayed for their inhibitory effects (IC50) on disaccharidase derived from the small intestine of rats. The IC50 value of ME was 3.2μg/mL for sucrase, 10μg/mL for isomaltase, and 51μg/mL for maltase. The IC50 value of MB was 0.36μg/mL for sucrase, 1.1μg/mL for isomaltase, and 6.2μg/mL for maltase. The IC50 value of 1-deoxynojirimycin as the principle component in ME was 0.015μg/mL for sucrase and 0.21μg/ mL for maltase, and this value was comparable to the IC50 of voglibose. The inhibitory activity of ME in α-amylase was weak. These results suggest that ME strongly suppresses postprandial hyperglycemia after carbohydrate loading by inhibiting the activity of disaccharidases in the small intestine of rats.
