1Instituto de Fermentaciones Industriales (Csic), Madrid, Spain
2Facultad de Medicina (Uam), Madrid, Spain
Objectives: Enzymatic hydrolysis of food proteins can release peptides able to exert different biological activities. In previous work we identified peptide sequences, such as RADHPFL and YAEERYPIL, derived from egg white hydrolysated with pepsin that inhibit angiotensin converting enzyme (ACE) in vitro and exhibit antihypertensive activity in spontaneously hypertensive rats. In this work we examined the effects of these peptides on the vasoconstrictor responses induced by angiotensin I and angiotensin II.
Design and Method: Aortic segments from 12-weeks-old Wistar Kyoto rats were mounted in an organ bath to analyze the vascular reactivity. The contraction produced by a single concentration of angiotensin I (1 μM) or angiotensin II (1 μM) in the absence or in the presence of RADHPFL (100 μM) and YAEERYPIL (100 μM) were studied. Captopril (ACE inhibitor prototype, 1 μM), and losartan (antagonist of AT1 receptor, 10 μM) were used as reference drugs. The results, expressed as means ± SEM of the number of rats indicated in each case, were analyzed by Student t test using the GraphPad Prism4 software. We were considered significant when P < 0.05.
Results and Discussion: Angiotensin I induced contractions in control preparations. Captopril markedly inhibited angiotensin I-induced contractions, suggesting that the vasoconstrictor effect of Angiotensin I is due to its transformation to angiotensin II. angiotensin II also produced contraction in aorta rings and this contraction was higher than angiotensin I. Losartan abolished the contraction produced by angiotensin II and angiotensin I. The sequences YAEERYPIL and RADHPFL also inhibited the angiotensin I and angiotensin II-induced contractions. These results suggest that the studied sequences could exert their antihypertensive effect not only through ACE-inhibitor pathway but also blocking the actions of angiotensin II. In conclusion, these peptides could be considered as an alternative for the control of hypertension and other related disorders.