Cyanidin-3-rutinoside alleviates postprandial hyperglycemia and its synergism with acarbose by inhibition of intestinal α-glucosidase

The inhibitory activity on intestinal α-glucosidase by cyanidin-3-rutinoside was examined in vitro and in vivo. The IC(50) values of cyanidin-3-rutinoside against intestinal maltase, and sucrase were 2,323 ± 14.8 and 250.2 ± 8.1 µM, respectively. The kinetic analysis revealed that intestinal sucrase was inhibited by cyanidin-3-rutinoside in a mixed-type manner. The synergistic inhibition also found in combination of cyanidin-3-rutinoside with acarbose against intestinal maltase and sucrase. The oral administration of cyanidin-3-rutinoside (100 and 300 mg/kg) plus maltose or sucrose to normal rats, postprandial plasma glucose was markedly suppressed at 30–90 min after loading. Furthermore, the normal rats treated with acarbose and cyanidin-3-rutinoside (30 mg/kg) showed greater reduction of postprandial plasma glucose than the group treated with acarbose alone. These results suggest that cyanidin-3-rutinoside retards absorption of carbohydrates by inhibition of α-glucosidase which may be useful as a potential inhibitor for prevention and treatment of diabetes mellitus.