Effects of tryptophan-containing peptides on angiotensin-converting enzyme activity and vessel tone ex vivo and in vivo.
Khedr. Sherif S; Deussen. Andreas A; Kopaliani. Irakli I; Zatschler. Birgit B; Martin. Melanie M
Key Findings
- IW peptide showed the strongest ACE‑inhibiting activity in human endothelial cells, followed by EW and WL.
- All three peptides prevented angiotensin‑I‑induced vasoconstriction in isolated rat aorta.
- Oral IW treatment for 14 weeks lowered aortic ACE activity and improved endothelium‑dependent relaxation in spontaneously hypertensive rats.
Practical Outcomes
- For DIY health enthusiasts, IW (isoleucine‑tryptophan) looks promising as a natural ACE‑inhibitor that could support blood‑pressure control and vascular function. However, the evidence is limited to cell cultures and rat studies, so any supplementation should start at low doses and be combined with regular monitoring of blood pressure. More human trials are needed before recommending a specific dosage or product.
Summary
A study found that short protein fragments containing the amino acid tryptophan—especially the pair isoleucine‑tryptophan (IW)—can block the enzyme that raises blood pressure (ACE) and stop blood vessels from tightening up in lab cells and in hypertensive rats. The rats that ate IW showed better blood‑vessel relaxation, suggesting the peptide might help keep blood pressure and vascular health in check.
Abstract
Over-activation of the renin-angiotensin axis and worsening of vascular function are critical contributors to the development of hypertension. Therefore, inhibition of angiotensin-converting enzyme (ACE), a key factor of the renin-angiotensin axis, is a first line treatment of hypertension. Besides pharmaceutical ACE inhibitors, some natural peptides have been shown to exert ACE-inhibiting properties with antihypertensive effects and potentially beneficial effects on vascular function. In this study, the ACE-inhibiting potential and effects on vascular function of tryptophan-containing peptides were evaluated. The ACE inhibitory action and stability of tryptophan-containing peptides was tested in endothelial cells-a major source of whole body ACE activity. Furthermore, the efficacy of peptides on vascular ACE activity, as well as vessel tone was assessed both ex vivo and in vivo. In human umbilical vein endothelial cells (HUVEC), isoleucine-tryptophan (IW) had the highest ACE inhibitory efficacy, followed by glutamic acid-tryptophan (EW) and tryptophan-leucine (WL). Whereas none of the peptides affected basal vessel tone (rat aorta), angiotensin I-induced vasoconstriction was blocked. IW effectively inhibited aortic ACE activity ex vivo taken from SHRs after 14-weeks of oral treatment with IW. Furthermore, IW treated SHRs showed better endothelium-dependent vessel relaxation compared to placebo. This study shows strong ACE-inhibiting effects of IW, EW and WL in HUVECs and aorta. The peptides effectively counteract angiotensin-induced vasoconstriction and preserve endothelium-dependent vessel relaxation. Thus, tryptophan-containing peptides and particularly IW may serve as innovative food additives with the goal of protection from angiotensin II-induced worsening of vascular function.
Study Information
pubmed
2017
2017-01-19T00:00:00.000Z
10.1007/s00394-016-1374-y
26
29