Inhibitory Effects of Gliadin Hydrolysates on BACE1 Expression and APP Processing to Prevent Aβ Aggregation

Alzheimer's disease (AD), a leading neurodegenerative disorder, is closely associated with the accumulation of amyloid-beta (Aβ) peptides in the brain. The enzyme β-secretase (BACE1), pivotal in Aβ production, represents a promising therapeutic target for AD. While bioactive peptides derived from food protein hydrolysates have neuroprotective properties, their inhibitory effects on BACE1 remain largely unexplored. In this study, we evaluated the inhibitory potential of protein hydrolysates from gliadin, whey, and casein proteins prepared using bromelain, papain, and thermolysin. Through in vitro and cellular assays, bromelain-hydrolyzed gliadin (G-Bro) emerged as the most potent BACE1 inhibitor, with an IC₅₀ of 0.408 mg/mL. G-Bro significantly reduced BACE1 expression and amyloid precursor protein (APP) processing in N2a/PS/APP cell cultures, suggesting its potential to attenuate Aβ aggregation. The unique peptide profile of G-Bro likely contributes to its inhibitory effect, with proline residues disrupting β-sheets, lysine residues introducing positive charges that hinder aggregation, hydrophobic residues stabilizing binding interactions, and glutamine residues enhancing solubility and stability. These findings highlight gliadin hydrolysates, particularly G-Bro, as potential natural BACE1 inhibitors with applications in dietary interventions for AD prevention. However, further studies are warranted to elucidate specific peptide interactions and their bioactivity in neural pathways to better understand their therapeutic potential.