Antihypertensive effect of ACE inhibitory oligopeptides from chicken egg yolks

Oligopeptides of 1 KDa or less were obtained by hydrolysis of chicken egg yolks with a crude enzyme, and by dialysis with a semipermeable membrane filter. Since the extracted peptides had an inhibitory action on the activity of angiotensin I-converting enzyme (ACE) in vitro, they were orally administered at 20, 100 and 500 mg/kg body weight to spontaneously hypertensive rats (SHR) for 12 weeks to analyze the physiological role on cardiovascular functions. The administered oligopeptides suppressed the development of hypertension at all dosages. After 12 weeks at 500 mg/kg body weight, the values for systolic, mean, and diastolic blood pressure were approximately 10% less in SHRs administered than controls. Furthermore, serum ACE activity of the peptide-administered groups was significantly lower than that of the control group in a dose-related manner. Our results imply that oligopeptides extracted from hen's egg yolks could potentially suppress the development of hypertension in SHR, and this effect might be induced by the inhibition of ACE activity.