Black highland barley anthocyanins as potent natural inhibitors of α-glucosidase and α-amylase: A combined digestion and molecular mechanism study.

This study investigated the α-glucosidase (α-G) and α-amylase (α-A) inhibitory properties of black highland barley anthocyanins (BHA) and its main monomer, cyanidin-3-O-glucoside (C3G), using an integrated approach combining in vitro simulated digestion, enzyme kinetics, multi-spectroscopic analyses, and molecular docking. Despite substantial degradation of anthocyanins during digestion, the intestinal digesta retained potent α-G inhibitory activity. The crude BHA extract exhibited stronger inhibition than C3G, with IC50 values of 8.31 μg/mL for α-G and 14.91 μg/mL for α-A. Kinetic studies revealed reversible, mixed-type inhibition for BHA, whereas C3G acted via a non-competitive mechanism. Multiple techniques demonstrated that the inhibitors bind to the enzymes, alter their conformation, and promote aggregation, with molecular docking attributing these effects to hydrogen bonding and hydrophobic interactions at the active site. These findings elucidate the mechanisms by which BHA and C3G modulate carbohydrate-hydrolyzing enzymes, highlighting BHA as a potent functional food ingredient for postprandial glycemic control.