Inhibition of wheat bran and it's active compoments on α-glucosidase in vitro

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Pharmacognosy Magazine,2013,9,36,309-314.
Published:September 2013
Type:Original Article
Authors:
Author(s) affiliations:

Jie Tu1, Jun Chen2, Shuyun Zhu3, Chunxiao Zhang2, Hua Chen2, Youbing Liu2
1Department of Food Quality and Safety, School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013; Department of Biotechnology and Engineering,College of Biology and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212018, China
2Department of Chinese Medicine and Pharmacology, School of Pharmacy, Jiangsu University, Zhenjiang, Jiangsu, 212013, China
3Department of Food Quality and Safety, School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013, China

Abstract:

Background: Wheat bran is a traditional Chinese medicine; however, it is mostly used as feedstuff in China. Wheat bran is widely accepted as an important ingredient in many low-glycemic index foods in modern western societies; however, its glycemic control mechanism is unknown. Objective: To determine potent α-glucosidase inhibitory compounds from wheat bran and to identify the inhibition on α-glucosidase . Materials and Methods: Ethanolic extract of wheat bran was prepared to evaluate the inhibitory activity on α-glucosidase, then fractionation of the extract was guided by in vitro enzyme-inhibition assay, and the potent α-glucosidase inhibitory compounds were identified by high performance liquid chromatography and atmospheric pressure chemical ionization-mass spectrometry; finally the enzyme inhibition process was studied using the Michaelis-Menton and the Lineweaver-Burk equations. Results: Both baker's yeast and rat intestinal enzymes were mostly inhibited (87.9% and 66.8% inhibition, respectively) at concentration 0.6 mg/mL of the ethanolic extract of wheat bran. The petroleum ether fraction in the ethanolic extract of wheat bran showed significant activity against rat intestinal α-glucosidase, and revealed a dose-dependent effect. The inhibition was 76.57% at 0.3 mg/mL and 100% at 0.6 mg/mL. The active fraction 13 of petroleum ether fraction was identified as alkylresorcinols (ARs). ARs showed strong inhibition towards α-glucosidase and its IC 50 value was found to be 37.58 ΅g/mL. The enzyme kinetic studies showed that, in the presence of ARs, the Michaelis-Menton constant (Km ) remains constant whereas the maximal velocity (Vmax ) decreases, revealing a non-competitive type of inhibition. Conclusion: The therapeutic potentiality of ARs in the management of the postprandial hyperglycemia will proliferate the utilization of wheat bran in controlling type 2 diabetes.

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