Identification and Characterization of Novel Angiotensin-Converting Enzyme Inhibitors Obtained from Goat Milk

Chromatographic separations of goat protein hydrolysate leading to the purification of β-CN f78–83, β-CN f84–87, and β-CN f181–184. A) Chromatogram of first purification step of goat milk protein hydrolysate using reverse-phase column chromatography. The arrow indicates the fraction (fraction 19) that showed the highest angiotensin I-converting enzyme (ACE) inhibitory activity after application of the fractions to a Caco-2 monolayer and assaying basolateral samples for that activity. B) The ACE inhibitory activities after application of the fractions to a Caco-2 monolayer. C) The HPLC chromatogram of second purification step of fraction 19. Arrows indicate the fractions that showed ACE inhibitory activity and that were used for peptide sequencing (left arrow: β-CN f78–83; middle arrow: β-CN f84–87; and right arrow: β-CN f181–184).

Systolic blood pressure (SBP) measured by tail-cuff plethysmography, in spontaneously hypertensive rats (SHR) fed a diet containing goat protein (GP-control), an ad libitum diet containing goat protein hydrolysate (GP-hyd) diet, and a diet containing goat protein and captopril (captopril) for 12 wk. Values are means±SEM; n=10. Two-way ANOVA revealed a statistical significance in time and between treatments (P<0.0005). *P<0.05 and **P<0.01 vs. GP-control group, detected by posthoc analysis.

Effects of chronic ad libitum diet containing goat protein hydrolysate (GP-hyd) and a diet containing goat protein and captopril (captopril) on the development of left ventricular and renal hypertrophy in spontaneously hypertensive rats (SHR). Organ hypertrophy is expressed as organ weight to BW ratio. Values are means±SEM, n=10. *P<0.05; **P<0.01 vs. diet containing goat protein (GP-control); ##P<0.01 vs. GP-hyd group.

Relaxation of aortic rings induced by acetylcholine (Ach; A) and sodium nitroprusside (SNP; B) in spontaneously hypertensive rats (SHR) fed different diets for 12 wk. A) Endothelium-dependent relaxation in intact aortic rings. B) Endothelium-independent relaxation in denuded aortic rings. Values are means±SEM; n=10 (1 aortic ring per animal, 10 animals per group). *P<0.05 and **P<0.01 vs. group fed diet containing goat protein (GP-control). The insets show the contractile tension induced by noradrenaline (panel A, 10⁻⁷ mol/L; panel B, 10⁻⁶ mol/L) in aortic rings from GP-control (open column), ad libitum diet containing goat protein hydrolysate (GP-hyd; solid column), or diet containing goat protein and captopril (captopril; dashed column) groups before the addition of ACh or SNP.

Angiotensin-converting enzyme (ACE) activity in different tissues from spontaneously hypertensive rats (SHR) after different treatments. Values are means±SEM; n=4. GP-control=a diet containing goat protein; GP-hyd=an ad libitum diet containing goat protein hydrolysate; captopril=a diet containing goat protein and captopril. *P<0.05 and **P<0.01 vs. GP-control group.