Novel Angiotensin-Converting Enzyme Inhibitory Peptides from Bungarus multicinctus: Simulated Gastrointestinal Digestion, Identification and Antihypertensive Mechanism.

Background/Objectives: Hypertension represents a leading contributor to cardiovascular disorders and premature mortality. Given the pervasive nature of adverse effects associated with current angiotensin-converting enzyme inhibitors (ACEIs), there is a significant interest in identifying novel bioactive lead compounds from natural sources. This study identifies, for the first time, three novel angiotensin-converting enzyme (ACE) inhibitory peptides released from Bungarus multicinctus (BM) via simulated gastrointestinal digestion (SGD). Methods: Active fractions were enriched by ultrafiltration and subjected to stability assessment. The peptide sequences were then determined using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) and bioinformatics tools, followed by chemical synthesis. Finally, the inhibitory mechanism was investigated using kinetic analysis and molecular docking. Results: The intestinal digest exhibited potent ACE inhibition, with the <5 kDa fraction achieving 79% inhibition at 1 mg/mL and demonstrating favorable stability under varying temperatures, pH, and ionic strengths. Molecular docking revealed strong binding (affinity < -9.9 kcal/mol) of the peptides PPSPPRW, WGFTKF, and PSLFPPRL to key ACE residues-Tyr523, His513, and Arg522-via hydrogen and hydrophobic interactions. Enzyme kinetics characterized PPSPPRW and WGFTKF as competitive inhibitors, and PSLFPPRL as mixed type. The peptides demonstrated acceptable cell viability at lower concentrations, establishing a preliminary safety window for therapeutic application. Conclusions: These findings establish BM as a valuable source of stable, bioactive ACE-inhibitory peptides (ACEIPs) acting as promising lead compounds for antihypertensive therapies.