Inhibitory effect of pine extract on α-glucosidase activity and postprandial hyperglycemia

Objective: This study investigated the inhibitory effect of pine bark extract (PBE) and needle extract on carbohydrate-hydrolyzing enzymes and the hypoglycemic effect in diabetic mice (Lep(ob) [ob/ob]). Methods: Pine bark and needle were dried and then placed in ethanol, and the extracts were assayed for the measurement of inhibition mode of PBE against alpha-amylase (EC 3.2. 1. 1) and a-glucosidase (EC 3.2.1.20). We also investigated the effect of long-term treatment with extracts on levels of postprandial blood glucose, body weight, food efficiency ratio, and gene expression of glucose transporter-4 in quadriceps muscle in diabetic mice (Lep(ob) [ob/ob]). Results: The PBE showed competitive inhibition against salivary a-amylase and the combination of non-competitive and uncompetitive inhibition against yeast alpha-glucosidase. In animal experiments, PBE effectively suppressed the increase of postprandial blood glucose level by delaying absorption of diet, and body weights of the group that received PBE were significantly lower than that in the group administered 0.5% carboxylmethyl cellulose (control) 21 d after administration. Conclusions: PBE can be used to suppress postprandial hyperglycemia of diabetic patients. It also can be applied for control of obesity by decreasing the food efficiency ratio, especially carbohydrates. (c) 2005 Elsevier Inc. All rights reserved.