Aqueous Extract of Annona macroprophyllata: A Potential α-Glucosidase Inhibitor

Annona genus contains plants used in folk medicine for the treatment of diabetes. In the present study, an aqueous extract prepared from Annona macroprophyllata (Annonaceae, also known as A. diversifolia) leaves was evaluated on both the activity of yeast alpha-glucosidase (an in vitro assay) and sucrose tolerance in Wistar rats. The results have shown that the aqueous extract from A. macroprophyllata inhibits the yeast alpha-glucosidase with an IC50 = 1.18 mg/mL, in a competitive manner with K-i = 0.97 mg/mL, a similar value to that of acarbose (K-i = 0.79 mg/mL). The inhibitory activity of A. macroprophyllata was reinforced by its antihyperglycemic effect, at doses of 100, 300, and 500 mg/kg in rats. Chromatographic analysis identified the flavonoids rutin and isoquercitrin in the most polar fractions of A. macroprophyllata crude extract, suggesting that these flavonoids are part of the active constituents in the plant. Our results support the use of A. macroprophyllata in Mexican folk medicine to control postprandial glycemia in people with diabetes mellitus, involving active constituents of flavonoid nature.