An Insight into the Mechanism Underlying the Inhibition of Starch Hydrolysis by (Poly)phenols: Direct α-Amylase Inhibition and/or Starch Complexation

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High postprandial glycaemic excursions are an important factor contributing to the development of insulin resistance and type 2 diabetes (T2D). (Poly)phenol consumption is associated with a reduced risk of T2D, partly attributed by α-amylase inhibition to reduce starch digestion. We present a new sensitive method to determine human α-amylase inhibition using maltoheptaoside (Mal-7) as substrate with direct chromatographic product quantification, compared with amylose/amylopectin hydrolytic products estimated using 3,5-dinitrosalicylic acid (DNSA). The pharmaceutical drug acarbose exhibited similar IC50 values with Mal-7, amylopectin or amylose as substrates, whilst varied results were observed for the polyphenols, epigallocatechin gallate (EGCG), quercetagetin and punicalagin. The polyphenols weakly inhibited Mal-7 (<50% inhibition) hydrolysis compared to amylose/amylopectin. (Poly)phenols may inhibit α-amylase through (1) direct action on the enzyme and/or (2) starch–(poly)phenol complexation. EGCG and punicalagin inhibited α-amylase mainly through starch complexation, whereas quercetagetin additionally binds to the α-amylase active site. The new method using Mal-7 as the substrate is superior for determining direct α-amylase inhibition, whilst the conventional DNSA method, using native starch as substrate, detects both inhibitory mechanisms. Accurately identifying (poly)phenols that inhibit α-amylase and their mode of inhibition could aid in developing dietary strategies focused on reducing postprandial glycaemia.
Original languageEnglish
Article number3.32
Pages (from-to)41-42
Number of pages2
Issue number1
Publication statusPublished - 1 Mar 2022
EventAnnual Scientific Meeting of the Nutrition-Society-of-Australia 2021: Opportunities for Nutrition Science in a New Era - virtual, Australia
Duration: 2 Dec 20213 Dec 2021
Conference number: 45th (The 45th Annual Scientific Meeting of the Nutrition Society of Australia was held virtually from 2–3 December 2021. The theme of the meeting was Nutrition: Opportunities for Nutrition Science in a New Era. Abstracts were submitted from 13 countries. A total of 326 registrants attended the conference, and 134 papers were presented consisting of 6 plenary, 54 oral and 74 poster presentations. This issue presents the proceedings of this meeting in the form of abstracts for papers presented at the conference)

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