Alleviating effects of lupeol on postprandial hyperglycemia in diabetic mice

This study aimed to investigate the inhibition activities of lupeol on carbohydrate digesting enzymes and its ability to improve postprandial hyperglycemia in streptozotocin (STZ)-induced diabetic mice. α-Glucosidase and α-amylase inhibitory assays were executed using a chromogenic method. The effect of lupeol on hyperglycemia after a meal was measured by postprandial blood glucose in STZ-induced diabetic and normal mice. The mice were treated orally with soluble starch (2 g/kg BW) alone (control) or with lupeol (10 mg/kg BW) or acarbose (10 mg/kg BW) dissolved in water. Blood samples were taken from tail veins at 0, 30, 60, and 120 min and blood glucose was measured by a glucometer. Lupeol showed noticeable inhibitory activities on α-glucosidase and α-amylase. The half-maximal inhibitory concentrations (IC₅₀) of lupeol on α-glucosidase and α-amylase were 46.23 ± 9.03 and 84.13 ± 6.82 μM, respectively, which were more significantly effective than those of acarbose, which is a positive control. Increase in postprandial blood glucose level was more significantly lowered in the lupeol-administered group than in the control group of both STZ-induced diabetic and normal mice. In addition, the area under the curve was significantly declined with lupeol administration in the STZ-induced diabetic mice. These findings suggest that lupeol can help lower the postprandial hyperglycemia by inhibiting carbohydrate-digesting enzymes.