CKD-711 and CKD-711a are aminooligosaccharide alpha-glucosidase inhibitors discovered during the bioactive material screening for antibacterial agent. Their inhibitory activities were studied and compared with those of acarbose in vitro and in vivo with animals. In in vitro study, CKD-711 showed similar effects to acarbose on porcine intestinal maltase and sucrase, IC50s of 2.5 and 0.5 microg/ml, respectively, whereas it had about 2 fold lower alpha-amylase inhibitory activity (IC50, 78.0 microg/ml) than acarbose (IC50, 36 microg/ml). CKD-711a showed less inhibitory activity than CKD-711 against all the enzymes tested. In rat fed on starch and sucrose meals, the dose of CKD-711 which reduced the postprandial blood glucose increment by 50 percent in comparison to control rats (ED50) were 3.07 and 1.15 mg/kg, respectively, and acarbose had ED50s of 1.94 and 1.15 mg/kg, respectively. CKD-711 and CKD-711a also showed antibacterial activity against Comamonas terrigena.