Compounds From Alisma Orientalis With Inhibitory Activities Of A-glucosidase

Rhizoma Alismatis,dried tuber of Alisma orientalis is widely used in varies of Chinese prescription.Previous research of our lab showed that the n-butanol fraction from Alisma orientalis(AOB)strongly inhibits a-glucosidase activity.In this dissertation,AOB was separated using silica gel column chromatography and three compounds were obtained(uracil,thymidine and guanosine).They were all obtained from Alisma orientalis at the first time.The a-glucosidase inhibitory activities of all the compounds were investigated using the pNPG method.At the concentration of 500O?g/mL,uracil,thymidine and guanosine showed inhibition of 37.7%,49.2%and 49.0%respectively.Moreover,the inhibitory activities against surcase and maltase were also tested in vivo.Compared to the control(acarbose)with IC50 0.015mg/mL,three of them were 0.393,0.283,0.017 for surcase.As for the inhibition of maltase,acarbose with IC50 0.045mg/mL and the three compounds were 1.379?1.304?1.648 respectively.However,acarbose showed effective inhibitory activity against porcine pancreas a-amylase with inhibition of 80.91%at the concentration of 2.000mg/mL.On the contract,the three compounds showed very lower inhibitor activity against a-amylase(<5%).Thus thymidine and guanosine would be a potential a-glucosidase inhibitor with effective inhibitory activity to a-glucosidase and less inhibition to a-amylase.Uracil was stable between the temperature of 37-100?,both thymidine and guanosine were stable between 37-80?;at the dose of 30?L with concentration of 500?g/mL,they all showed the strongest inhibition.Three inhibitors were compatible with a-glucosidase as the reactive time was 12min.Thymidine and guanosine belong to competitive inhibitor while uracil was uncompetitive inhibitor.Intestinal glucose absorptions of the three compounds were studied using noneverted intestinal sacs.All the three compounds showed stronge inhibition of glucose absorption.At the concentration of 1mg/mL,thymidine showed the strongest inhibition of 57.21%,uracil and guanosine were 35.57%and 45.67%respectively.