Structural basis for the anti-aging effects of hydroxyproline-BCAA dipeptides: An integrated computational and experimental approach.

This study systematically investigated the structure-activity relationships of nine hydroxyproline-branched-chain amino acid dipeptides to elucidate their anti-aging potential. Quantum chemical calculations revealed that electronic properties, particularly a lower HOMO-LUMO energy gap (ΔE) and chemical hardness (η), were critical structural determinants governing the peptides' radical scavenging efficiencies against DPPH and ABTS. Structurally flexible linear dipeptides consistently outperformed their rigid cyclic analogues, potently suppressing pro-inflammatory mediators (TNF-α, IL-6) in RAW264.7 macrophages and extending Caenorhabditis elegans lifespan by up to 15 % through enhancing endogenous antioxidant defenses. Molecular docking provided a structural basis for these activities, demonstrating favorable binding affinities to the Keap1-Kelch domain and TNF-α. A composite bioactivity score derived from multivariate analysis identified Hyp-Ile and Leu-Hyp as the most potent candidates. Notably, Hyp-Ile's specific structure conferred the lower energy gap ΔE = 6.11 eV, which directly translated to markedly higher radical scavenging activity (91.58 % for DPPH; 88.58 % for ABTS) compared to its analogues and the stronger binding affinities to Keap1 (-7.111 kcal/mol) and TNF-α (-6.168 kcal/mol), establishing a clear mechanistic link between its electronic configuration and multifaceted bioactivity. These findings position Hyp-Ile and Leu-Hyp as promising, structurally-defined functional food ingredients.