Hexane fraction from Brazilian Morus nigra leaves improved oral carbohydrate tolerance and inhibits α-amylase and α-glucosidase activities in diabetic mice

Morus nigra, popularly known as mulberry, has been traditionally used as anti-diabetic herbal medication. This study focused on hexane fraction from Brazilian M. nigra leaves (Hex-Mn) effects on digestion and absorption of carbohydrate in diabetic mice. The high-performance liquid chromatography (HPLC) analysis was performed, and showed the presence of flavonoids isoquercetin and kaempferol-3-O-rhamnoside. Hex-Mn did not alter oral glucose tolerance test; however, it prevented hyperglycemia in oral sucrose and starch tolerance test in diabetic mice. Also, Hex-Mn was more efficient to inhibit the α-glucosidase, showing lower inhibitory effect on α-amylase activity in vitro. The results suggest that Hex-Mn may delay the carbohydrate digestion, but not glucose transport through brush border membrane of the intestine, which contribute with reduction in postprandial hyperglycemia in mice. Hex-Mn has antihyperglycemic effect by attenuating the carbohydrate digestion in diabetic mice, which could be explained, at least in part, by the presence of isoquercetin and kaempferol-3-O-rhamnoside.