α-Glucosidase Inhibitory Activity of Polyphenols from the Burs of Castanea mollissima Blume

Jianwei Zhang,Shan Zhao,Peipei Yin,Lingling Shi,Xiaojing Zhou,Linlin Yan,Jin Han,Yujun Liu,Chao Ma

doi:10.3390/molecules19068373

Abstract

Polyphenol extracts from the burs of Castanea mollissima Blume (CMPE) exhibited potential antioxidant and hypoglycemic activities. The α-glucosidase inhibitory activities of CMPE were assessed as a means of elucidating the mechanism behind its hypoglycemic activities. In vitro studies showed that CMPE significantly inhibited both yeast α-glucosidase, through a noncompetitive mode with an IC50 of 0.33 μg/mL, and rat intestinal α-glucosidase. In vivo studies revealed that oral administration of CMPE at doses of 600 mg/kg significantly reduced postprandial blood glucose levels by 27.2% in normal rats following sucrose challenges. Gel permeation chromatography revealed that CMPE exhibited typical characteristics of high-molecular-mass polymers with mean (Mn) and weight (Mw) average molecular weights of 35.4 and 50.7 kDa, respectively, and a polydispersity (Mw/Mn) of 1.432. Acid hydrolysis analysis indicated the presence of ellagitannins. These data suggest that CMPE, enriched with ellagitannins, would be an efficacious dietary supplement for diabetes management through the inhibition of alpha-glucosidase.

Highlights

One of the most common metabolic diseases, is caused by a deficiency in insulin levels; type 2 diabetes is characterized by hyperglycemia due to defects in insulin secretion, action, or both [1,2] and has rapidly become a physical and mental burden that lowers the quality of life and results in high rates of mortality and disability
Balancing postprandial blood glucose levels is extremely important, since postprandial hyperglycemia is considered more dangerous than fasting blood glucose [3]. α-Glucosidase can release glucose by hydrolyzing linear and branched isomaltose oligosaccharides, resulting in postprandial hyperglycemia
Polyphenol extracts from the burs of Castanea mollissima Blume (CMPE), which is native in China and cultivated in North American and Asia as an economic crop, were shown to exhibit antioxidant, hypolipidemic, and hypoglycemic properties [2]

Summary

Introduction

One of the most common metabolic diseases, is caused by a deficiency in insulin levels; type 2 diabetes is characterized by hyperglycemia due to defects in insulin secretion, action, or both [1,2] and has rapidly become a physical and mental burden that lowers the quality of life and results in high rates of mortality and disability. Identifying and characterizing the inhibitors of α-glucosidase that can be used therapeutically is important [4,5]. Ellagitannins and EA have been studied primarily with regard to their positive effects on human health and for their physiological properties such as antitumor, anti-peroxidase, antiviral, antioxidant, and anti-foodborne pathogen and antimutagenic activities [17]. Polyphenol extracts from the burs of Castanea mollissima Blume (CMPE), which is native in China and cultivated in North American and Asia as an economic crop, were shown to exhibit antioxidant, hypolipidemic, and hypoglycemic properties [2]. Many mechanisms exist by which an oral therapeutic agent can exhibit hypoglycemic properties, including insulin sensitization, stimulation of insulin release, and the inhibition of α-glucosidase [18].

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