Serviceberry [Amelanchier alnifolia (Nutt.) Nutt. ex. M. Roem (Rosaceae)] leaf extract inhibits mammalian α-glucosidase activity and suppresses postprandial glycemic response in a mouse model of diet-induced obesity and hyperglycemia

Ethnopharmacological relevance: Serviceberry or Saskatoon berry [Amelanchier alnifolia (Nutt.) Nutt. ex. M. Roem (Rosaceae)], native to the North Glacier forests of the Rocky Mountains in Montana, has been used by the Blackfeet Indian tribe in alleviation of diabetes. Anecdotally, tea made from twigs and leaves have been used for optimum health and diabetes management. However, such traditional knowledge of the medicinal properties of Amelanchier alnifolia has not been validated by scientific studies. The goal of this study was to identify potential antidiabetic mechanisms of serviceberry. Materials and Methods: Serviceberry plant samples consisting of leaves, twigs, and leaves with berries were extracted and fractionated. Ethyl acetate and water fractions were tested for inhibition of alpha-glucosidase activity in vitro. Diet-induced obese, hyperglycemic C57B16 mice were administered serviceberry leaf extract prior to sucrose-, starch-, or glucose-loading to test for alpha-glucosidase inhibition and decreased post-prandial glycemic response. Results: In the course of screening for potential antidiabetic mechanisms, serviceberry leaf extracts and subfractions demonstrated potent inhibitory activity against mammalian intestinal alpha-glucosidase activity (EC 3.2.1.20). Further, in an animal model of diet-induced obesity and hyperglycemia, serviceberry leaf subtraction demonstrated significant inhibition of intestinal alpha-glucosidase activity, and delayed the absorption of carbohydrates, resulting in significant lowering of post-prandial blood glucose concentrations, similar to the antidiabetic drug Acarbose (TM). Conclusions: These findings indicating that serviceberry leaf extract may lower post-prandial glycemic response corroborate traditional knowledge of the Blackfeet Indians of Montana, and potentially offer a complementary approach in the treatment of diabetes. Published by Elsevier Ireland Ltd.