valyltyrosine and isoleucyl-tyrosine

In this study, we found that antihypertensive di-peptide Val-Tyr (VY) showed a vascular relaxation effect in KCl-induced contraction of thoracic aorta rings from 18-week-old spontaneously hypertensive rats among di-peptides of VY, Ile-Tyr, and Tyr-Val irrespective of their angiotensin I-converting enzyme inhibitory activity. The effect was endothelium-independent, and was closely associated with vascular responses in the vascular smooth muscle layer.

Topics: Animals; Antihypertensive Agents; Aorta, Thoracic; Dipeptides; In Vitro Techniques; Male; Muscle Contraction; Rats; Rats, Inbred SHR; Vasodilation; Vasodilator Agents

We have shown that Protease N treated Royal Jelly (ProRJ) and peptides from ProRJ (Ile-Tyr (IY), Val-Tyr (VY), Ile-Val-Tyr (IVY)) inhibited angiotensin I-converting enzyme (ACE) activity and they have an antihypertensive effect in repeated oral administration for 28 d on spontaneously hypertensive rats (SHR). We investigated the contributive ratio of these peptides in ProRJ for antihypertensive effect in single oral administration on SHR. In single oral administration of each peptide and peptides mixture (MIX; IY, VY and IVY) at doses of 0.5, 1 and 10 mg/kg, systolic blood pressure (SBP) of SHR was reduced dose-dependently. This antihypertensive effect was held for 8 h. These results suggest that peptides contributed to the antihypertensive effect of ProRJ. And the contributive ratio of MIX in ProRJ for antihypertensive effect was computed to be about 38%. Therefore it is considered that intake of peptides, as a functional food would be beneficial for improving blood pressure in people with hypertension.

Topics: Administration, Oral; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Blood Pressure; Dipeptides; Fatty Acids; Male; Oligopeptides; Rats; Rats, Inbred SHR; Serine Endopeptidases; Time Factors