A novel ACE inhibitory peptide derived from alkaline hydrolysis of ostrich (Struthio camelus) egg white ovalbumin.

Graphical abstract Highlights • Alkaline hydrolysis enhanced ACE inhibitory activity of ovalbumin ostrich egg white. • Try-Val has been further demonstrated a competitive inhibitory property. • Hydrogen bond and hydrophobic interaction stabilize the binding between YV and ACE. • Peptide showed non-toxicity to human red blood cells, HaCaT and MRC-5 cells. • Try-Val could be absorbed in human intestinal Caco-2 cells monolayer. Abstract In this research, ovalbumin (OOW), one of the major components in ostrich egg white, was purified by anion exchange chromatography. Then, the purified OOW was subjected to alkaline hydrolysis (0.25 M NaOH) at 40 °C for 2–10 h. The best angiotensin I-converting enzyme (ACE) inhibitory activity was observed at 8 h of hydrolysis. The OOW hydrolysate obtained at 8 h (8 h-hOOW) was purified by the reversed-phase high-performance liquid chromatography (RP-HPLC). The resulting peptide, YV, exhibited an IC 50 value of 63.97 μg/mL. Using a Lineweaver-Burk plot, YV was determined to be a competitive inhibitor, and the inhibition constant (K i) was found to be 55.20 μg/mL. The molecular docking analysis revealed that the binding between YV and the S1 and S2 pocket sites of ACE was mainly stabilized by a hydrogen bond. Moreover, YV maintained ACE inhibitory activity after gastrointestinal digestion and showed no cytotoxic effects on human red blood cells, human keratinocyte cells (HaCaT) and human lung fibroblasts cells (MRC-5). An in vitro test of intestinal absorption showed that YV had a high potential for absorption into the Caco-2 cell monolayer model. Therefore, these results suggest that the YV peptide can be applied for the development of novel natural antihypertensive products. [ABSTRACT FROM AUTHOR]