Objective Taking 41 kinds of Chinese herbal medicines commonly used in Meizhou Hakka as the research object,their inhibitory activities against α-glucosidase and α-amylase were screened and the enzyme inhibition types of the species with the strongest activities were explored.Methods The inhibitory activities of 41 commonly used Hakka herbs in Meizhou against α-glucosidase and α-amylase were evaluated by the p-Nitrophenyl a-D-mannopyranoside(pNPG)method and the 3,5-Dinitrosalicylic acid(DNS)method,using the inhibitory rate of half(IC50)as an index.The inhibitory activity of 95%ethanol extracts of 41 Chinese herbal medicines commonly used in Meizhou Hakka on α-glucosidase and α-amylase were analysed.The enzymatic kinetics method and Lineweaver-Burk curve were used to analyze the inhibitory type of the most active species.Results The results showed that 40 Chinese herbal medicines commonly used in Meizhou Hakka had α-glucosidase inhibitory activity,and 23 medicines had α-amylase inhibitory activity,among which Psychotria asiatica Wall.showed the strongest inhibitory activity with the IC50 values aganist α-glucosidase and α-amylase of 0.17±0.001 mg·mL-1 and 0.09±0.001 mg·mL-1,respectively.The inhibition types were reversible competitive inhibition and reversible non-competitive inhibition,respectively.Conclusion The Psychotria asiatica Wall.Chinese herbal medicines commonly used in Meizhou Hakka has significant inhibitory effect on the activity of glucose metabolism enzymes,which has potential value for further research and development on the prevention and treatment of diabetes mellitus.

OBJECTIVE： To compare inhibitory effects of ethanol extract of different medicinal parts （root， stem， leaf， seed， flower and flesh） from Syzygium jambos on the activities of α-glycosidase and α-amylase. METHODS： Using half-inhibitory concentration value （IC50） as evaluation index， acarbose as positive control， inhibitory effects of ethanol extract of different medicinal parts from S. jambos on the activities of α-glycosidase （from yeast and small instestine in mice） and α-amylase were evaluated with in vitro inhibition model. The enzymatic dynamics and Lineweaver-Burk methods were used to analyze the inhibitory type of the best medicinal part on the activities of α-glycosidase and α-amylase. RESULTS： In the yeast α-glucosidase inhibitory activity test， the order of inhibitory activity was S. jambos seed＞S. jambos stem＞S. jambos leaf＞S. jambos root＞S. jambos flower＞S. jambos flesh＞acarbose. In the mice intestine α-glucosidase inhibitory activity test， the order of inhibitory activity was S. jambos seed＞S. jambos stem＞S. jambos root＞S. jambos leaf＞S. jambos flower＞S. jambos flesh＞acarbose. In the α-amylase inhibitory activity test， the order of inhibitory activity was acarbose＞S. jambos seed＞S. jambos stem＞S. jambos root＞S. jambos leaf＞S. jambos flesh＞S. jambos flower. Ethanol extract of S. jambos seed had the stronger inhibition activity against α-glucosidase from yeast，α-glucosidase from small intestine in mice and α-amylase than other medicinal parts [IC50 were（6.64±0.24）， （32.77±2.46） and （41.18±1.63） μg/mL]. Ethanol extract of S. jambos seed had the stronger inhibition activity against α-glucosidase than acarbose [IC50 to α-glucosidase from yeast and α-glucosidase from small intestine in mice were （2 833.33±5.48）， （1 304.21±6.45） μg/mL] （P＜0.05）. The inhibitory effect of ethanol extract from S. jambos on the activity of α-amylase was less than that of acarbose [IC50 was （27.27±1.24） μg/mL] （P＜0.05）. Enzymatic dynamics showed that the inhibitory type of ethanol extract from S. jambos seed on α-glucosidase and α-amylase were both reversible competitive inhibition. CONCLUSIONS： Among different parts of S. jambos such as root， stem， leaf， seed， flower and flesh， S. jambos seed shows the strongest inhibitory effects on the activities of α-glucosidase and α-amylase， which has the value of being developed for the treatment of diabetes or health food.