Effect of different angiotensin-converting enzyme inhibitory products obtained from egg white proteins in hypertensive rats
- M. MIGUEL, R. LÓPEZ-FANDIÑO, M. RAMOS, M. A. ALEIXANDRE
- Journal of Hypertension (submitted)
Enzymatic hydrolysis of food proteins can release peptides able to exert different biological activities. Among the bioactive peptides known so far, those with angiotensin converting enzyme (ACE)inhibitory properties are receiving special attention due to their potential beneficial effects in the treatment of hypertension. In previous work we identified active peptide sequences that derive from ovalbumin by enzymatic hydrolysis. We have now explored the possibility of using high hydrostatic pressure to change the proteolytic pattern of ovalbumin and promote the release of bioactive peptides. Pressurization of ovalbumin up to 400 MPa during enzyme treatments greatly enhanced its hydrolysis and the resulting peptides exerted a considerable ACE inhibition in vitro. Hydrolysis under high pressure changed the proteolytic pattern and led to the transient accumulation of intermediate hydrophobic peptide products. In addition, we have also evaluated the impact of gastrointestinal digestion on the integrity and activity of two peptides derived from ovalbumin, YAEERYPIL and RADHPFL, that inhibit ACE in vitro and exhibit in vivo antihypertensive activity in spontaneously hypertensive rats (SHR). Our aim was to further understand the in vivo effects and elucidate whether the intact sequences had physiological relevance in blood pressure regulation. The results showed that both peptides were susceptible to proteolytic degradation after incubation with pepsin and a pancreatic extract. Furthermore, their ACEinhibitory activity in vitro decreased after simulated digestion. The antihypertensive activity on SHR of the end products of the gastrointestinal hydrolysis of YAEERYPIL and RADHPFL, that were YPI and RADHP, respectively, was evaluated. Both significantly decreased blood pressure, 2 hours after administration, at doses of 2 mg/kg, but probably they did not exert their antihypertensive effect through an ACE-inhibitory mechanism.