Fermented milk containing lactotripeptides IPP and VPP did not inhibit plasma or endothelial ACE in vivo, whereas captopril decreased plasma ACE activity by 82.3%.
Does fermented milk containing lactotripeptides IPP and VPP inhibit ACE in vivo in healthy normotensive men?
Fermented milk containing lactotripeptides IPP and VPP does not inhibit ACE in vivo in humans, challenging the proposed mechanism for its potential blood pressure-lowering effects.
BACKGROUND: The potential blood pressure lowering effect of fermented milk may involve inhibition of angiotensin-converting enzyme (ACE) by dairy lactotripeptides generated during milk fermentation, such as isoleucine-proline-proline (IPP) and valine-proline-proline (VPP). These peptides are weak ACE inhibitors in vitro but it remains unclear whether they inhibit ACE in vivo in humans. OBJECTIVE: To assess in vivo ACE inhibition in individuals given fermented milk over a 7-day period. DESIGN AND METHODS: Twelve healthy normotensive men were given 330 ml of fermented milk once daily from day 1 to day 7 (IPP: 4.5 mg and VPP: 6.6 mg) and a single dose of 50 mg captopril on day 8. ACE inhibition was assessed in vivo by measuring plasma and urine AcSDKP and plasma active renin and in vitro by measuring plasma ACE activity using hippuryl-histidine-leucine. Plasma IPP/VPP concentrations were measured by LC/MS/MS. RESULTS: Plasma IPP concentrations increased slightly and very transiently after fermented milk administration. Plasma VPP concentrations were below the limit of quantification. Fermented milk had no effect on plasma AcSDKP, ACE activity or active renin concentrations on days 1 or 7. Urine AcSDKP excretion underwent a small transient increase. In contrast, plasma and urine AcSDKP increased 7.7-fold and 70-fold, respectively, and plasma ACE activity decreased by 82.3 +/- 16.1% following captopril administration; plasma active renin concentration increased four-fold. CONCLUSION: IPP and VPP were poorly absorbed and rapidly eliminated. They did not inhibit plasma or endothelial ACE in vivo at the selected doses and had no specific effect on the N-terminal or C-terminal ACE domains.
Wuerzner et al. (Thu,) conducted a other in Healthy normotensive (n=12). Fermented milk vs. Captopril was evaluated on In vivo ACE inhibition (plasma and urine AcSDKP, plasma active renin, plasma ACE activity). Fermented milk containing lactotripeptides IPP and VPP did not inhibit plasma or endothelial ACE in vivo, whereas captopril decreased plasma ACE activity by 82.3%.