Inhibition of Carbohydrate Hydrolysing Enzymes, Antioxidant Activity and Polyphenolic Content of Beilschmiedia Species Extracts

Y N Tay,M N Azmi,M H A Bakar,K Awang,M Litaudon,N A Saad,M A Kassim

doi:10.1088/1757-899x/716/1/012007

Abstract

The goal of the present study was to provide in vitro evidence for potential inhibition of carbohydrate hydrolysing enzymes and antioxidant activities of methanol and ethyl acetate extracts from barks of two different Beilschmiedia species. These extracts were tested on α-amylase and α-glucosidase inhibitory activities, mode of enzyme inhibition, total polyphenolic content (TPC) and antioxidant capabilities. Methanolic bark extract of Beilschmiedia insignis demonstrated optimum inhibitory effects against α-amylase and α-glucosidase with IC50 values of 3.233 µg/mL and 12.357 µg/mL, respectively. Further analysis of inhibition mode revealed that the extract demonstrated a mixed inhibition against both enzymes. In comparison to other extracts, methanolic bark extract of Beilschmiedia insignis demonstrated the highest TPC content of 420.393 mg GAE/g extract, lowest IC50 value of 12.103 µg/mL for DPPH radical scavenging ability and highest FRAP value of 1904.247 µM Fe (II)/mg extracts, indicating the antioxidant potential of the extract. A significant strong correlation coefficient was observed between TPC with FRAP (r = 0.994, p < 0.01) and TPC with DPPH (r = -0.860, p < 0.01), signifying that antioxidant activity and reducing capability were contributed by the polyphenolic compounds present in the crude extract. Collectively, methanolic bark extract of Beilschmiedia insignis possessed significant carbohydrate hydrolyzing enzyme inhibitory effects and antioxidant activity, suggesting its possible alternative application for diabetes and postprandial hyperglycemia treatment.

Highlights

IntroductionPublished under licence by IOP Publishing Ltd leading cause of death in women [1]
The therapeutic approach for diabetes mellitus (DM) should be based on targeting glucose metabolism and oxidative stress caused by hyperglycemia-related conditions [3]
For Į-amylase inhibition, BIM extract had the lowest IC50 value of 3.233 ± 0.512 μg/mL, which explains the better potency of BIM extract in LQKLELWLQJ Į-amylase, delaying the breakdown and absorption of carbohydrates and lowering the glucose peaks encountered in postprandial glucose [14]

Summary

Introduction

Published under licence by IOP Publishing Ltd leading cause of death in women [1]. DM is characterized by high glucose level in the blood (hyperglycemia) associated by disturbances in carbohydrates, proteins and fats metabolism. Such defects in these metabolic pathways may lead to complete or partial insufficiency of insulin actionand/ or insulin resistance with macro-microvascular complications [2]. Previous studies reported that prolonged hyperglycemia is the key to these DM complications as it causes an increase in oxidative stress due to excess generation of free radicals through protein glycation, glucose oxidation and lipid peroxidation [3]. The therapeutic approach for DM should be based on targeting glucose metabolism and oxidative stress caused by hyperglycemia-related conditions [3]

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