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

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 degrees C for 210 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 IC50 value of 63.97 mu g/mL. Using a Lineweaver-Burk plot, YV was determined to be a competitive inhibitor, and the inhibition constant (Ki) was found to be 55.20 mu g/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.