Inhibition of digestive enzymes with EGCG-loaded inverse alginate beads: a strategy for modulating starch digestion

This study developed epigallocatechin gallate (EGCG)-loaded alginate-starch liquid-core beads (LCBEx) as a novel approach to modulating starch digestion. The incorporation of EGCG noticeably altered the physicochemical properties of the beads, leading to a reduction in average diameter and porosity, and the emergence of a more dense mesh architecture. Mechanism studies revealed that the EGCG-enriched beads (LCBE_1%) strongly quenched the innate fluorescence property of α-amylase and α-glucosidase via a mixed quenching mechanism (both dynamic and static). Circular dichroism spectroscopy further revealed EGCG-induced conformational adjustments in both enzymes, characterized by increased α-helix and random coil contents and decreased β-sheet structures. Molecular docking simulations confirmed the spontaneous binding of EGCG to the catalytic sites of the enzymes, mainly through van der Waals interactions and hydrogen bonding, with binding energies of -7.9 kcal/mol for α-amylase and -5.6 kcal/mol for α-glucosidase. Consequently, the in vitro digestibility of starch was remarkably altered. With 1% EGCG loading, the resistant starch content significantly increased from 43.00% to 61.88%, while the estimated glycemic index decreased from 67.99 to 57.58. Overall, these findings highlight the potential of polyphenol-functionalized hydrogel beads as an effective strategy for designing starch-based foods with controlled glycemic response.