Egg-derived ACE-inhibitory peptides IQW and LKP reduce blood pressure in spontaneously hypertensive rats

Two angiotensin converting enzyme (ACE) inhibitory tripeptides, IQW and LKP, were previously characterized from egg white protein ovotransferrin. ACE is a key enzyme of the renin–angiotensin system (RAS) which generates angiotensin II (Ang II) from its precursor and increases blood pressure (BP) in the body. This study tested the blood pressure lowering potential of orally administered IQW and LKP in spontaneously hypertensive rats. IQW and LKP treatment decreased mean blood pressure (MAP) by ~19 and ~30 mmHg, respectively, compared to untreated SHRs. The change in BP was accompanied by the preservation of nitric oxide dependent vasorelaxation and lowering of plasma Ang II levels. Furthermore IQW, but not LKP, also reduced intercellular adhesion molecule-1 (ICAM-1) expression and nitrotyrosine levels in arteries, suggesting additional protective effects against inflammation and oxidative/nitrosative stress. These results demonstrate anti-hypertensive effects of IQW and LKP in vivo and a reduction of circulating Ang II levels, with additional anti-inflammatory and antioxidant effects mediated by IQW.