Improving Activity of ACE Inhibitory Peptide by Sequence-Based Rational Design: Properties, Function on Endothelial Cells, and Potential Antihypertensive Mechanism

The comprehension of the relationship between structure and function and mechanisms of intermolecular interactions within amino acid sequences is essential for developing potent angiotensin-converting enzyme (ACE) inhibitory peptides based on food-derived peptide sequences. This study developed six peptides based on the original ACE inhibitory peptide LYPVK that was derived from Ficus carica by sequence-based rational design and investigated their ACE inhibitory functions. Three of them demonstrated improved activity, among which YWLKP had the strongest activity, with an IC₅₀ value of 5.02 ± 0.62 µg/mL. They exhibited competitive or noncompetitive action modes and desirable resistance to gastrointestinal environments. Molecular docking analysis revealed that the enhanced hydrogen bonds and hydrophobic interactions contribute to their increased affinity for ACE. Accordingly, the potential sequence regularity was proposed that peptides containing residue composition of X1-X2-Lys-Pro motifs (X1 represents hydrophobic aromatic residues and X2 represents hydrophobic residues with long side chains) may exhibit strong activity against ACE. It was found that these peptides promoted nitric oxide (NO) release and reduced endothelin-1 (ET-1) content to achieve antihypertensive effects on endothelial cells. Additionally, YWLKP might regulate multiple targets and pathways for its antihypertensive function through network pharmacology and real-time fluorescence quantitative PCR (RT-qPCR) analysis. This study provides potential sequence regularity and sequence-designed peptides that can serve as promising multitarget ACE inhibitors.