D-Psicose Inhibits Intestinal α-Glucosidase and Suppresses the Glycemic Response after Ingestion of Carbohydrates in Rats

D-psicose is one of the rare sugars present in small quantities in commercial carbohydrates and agricultural products. In this study, we investigated the effects of D-psicose on the activities of alpha-amylases and alpha-glucosidases in vitro, and evaluated the effects of D-psicose on the in vivo postprandial glycemic response using rats. In the in vitro study, D-psicose potently inhibited the intestinal sucrase and maltase, however, slightly inhibited the intestinal and salivary alpha-amylase activities. Male Wistar rats (6 months old) were administrated 2 g/kg of sucrose, maltose or soluble starch together with 0.2 g/kg of D-psicose or D-fructose. The D-psicose significantly inhibited the increment of plasma glucose concentration induced by sucrose or maltose. The starch-induced glycemic response tended to be suppressed by D-psicose, however the suppression was not significant. These results suggest that D-psicose inhibits intestinal sucrase and maltase activities and suppresses the plasma glucose increase the normally occurs after sucrose and maltose ingestion. Thus, D-psicose may be useful in preventing postprandial hyperglycemia in diabetic patients when foods containing sucrose and maltose are ingested.