Antihypertensive effect of enzymatic hydrolysate of collagen and Gly-Pro in spontaneously hypertensive rats.

Continuous oral feeding of enzymatic hydrolysate of porcine skin collagen showed an antihypertensive effect in spontaneously hypertensive rats (SHRs). We isolated an angiotensin I-converting enzyme (ACE) inhibitory peptide, Gly-Phe-Hyp-Gly-Pro (IC(50)=91 microM), from the hydrolysate, but the ACE inhibitory activities of the other peptides isolated were weak. Although the ACE inhibitory activity of Gly-Pro (IC(50)=360 microM) was not potent, Gly-Pro exists in collagen as a large number of repeated sequences. We then examined the antihypertensive effect of Gly-Pro. Orally administered Gly-Pro at 500 mg/kg significantly decreased the blood pressure of SHRs, and at 50 mg/kg it also showed a tendency to lower the blood pressure. Oral administration of Gly-Phe-Hyp-Gly-Pro (10 or 30 mg/kg) also decreased the blood pressure of SHRs.