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Exploring inhibitory mechanism of gallocatechin gallate on a-amylase and a-glucosidase relevant to postprandial hyperglycemia

Wu, Xiaqing, Ding, Huafang, Hu, Xing, Pan, Junhui, Liao, Yijing, Gong, Deming, Zhang, Guowen
Journal of functional foods 2018 v.48 pp. 200-209
acarbose, active sites, alpha-amylase, alpha-glucosidase, amino acids, diabetes, enzyme activity, enzyme inhibition, enzyme inhibitors, epigallocatechin, functional foods, hyperglycemia, patients
The postprandial hyperglycemia of diabetic patients is associated with a-amylase and a-glucosidase, searching safer enzyme inhibitors and deciphering their inhibition mechanism are important. In this study, gallocatechin gallate (GCG) was found to exert strong inhibition on α-amylase and α-glucosidase in the mixed-type and non-competitive manners, respectively. GCG could bind with α-amylase and α-glucosidase to form the complexes, which induced conformational changes of the two carbohydrate digestive enzymes. Docking analysis verified that GCG interacted with pivotal amino acids within the active site of α-amylase, while it bound to a site close to the active site of α-glucosidase, which might affect active site, causing declines in a-amylase and α-glucosidase activities. Moreover, the combination of GCG with acarbose increased the inhibition of α-amylase and α-glucosidase and reduced the dosage of acarbose. This study may provide theoretical basis for designing novel functional foods of GCG for the prevention and treatment of diabetes.