Control of postprandial hyperglycaemia by galactosyl maltobionolactone and its novel anti-amylase effect in mice

Abstract

The ability to control carbohydrate digestion is useful in the treatment of diabetes mellitus and obesity. In the present study, we examined whether recently developed 4 2- O-β-D-galactosyl maltobionolactone (LG2O) having anti-amylase activity is able to control postprandial blood glucose concentration in mice. In addition, we tried to determine how LG2O regulates carbohydrate delivery in the gut lumen by conducting in vivo and in vitro studies. Male non-diabetic ddY mice and KK-A y mice, a spontaneously diabetic strain, had free access to a carbohydrate rich diet supplemented with LG2O (3 or 10 g/kg) for 0.5 hr, and blood glucose concentration was measured. LG2O suppressed any steep increase in postprandial blood glucose concentration in both ddY and KK-A y mice. Corresponding to the blood glucose response, LG2O also markedly suppressed any increase in postprandial plasma insulin concentration. After ingestion of the diet, LG2O produced a 1.5–3.5 fold increase in the gut contents and reducible sugar content in the small intestine but not in the stomach. Although α-amylase activity in the stomach was much lower compared with the activity in the small intestine, LG2O still strongly inhibited α-amylase activity in the stomach. In contrast, LG2O had little or no influence on α-amylase activity in the proximal intestine. From the in vitro carbohydrate digestion stimulation, LG2O at 7.5 mM decreased glucose production by 75% for dextrin, 25% for α-starch and 60% for raw starch. In conclusion, administration of LG2O inhibits carbohydrate digestion in the gut, and produces significant improvements in both blood glucose and insulin response following ingestion as part of the diet, and this evidence provides support for its therapeutic potential in treating diabetes mellitus and obesity.