Antihypertensive effect of novel angiotensin I converting enzyme inhibitory peptide from chum salmon (Oncorhynchus keta) skin in spontaneously hypertensive rats

Angiotensin I converting enzyme (ACE) inhibitory peptide was separated from chum salmon (Oncorhynchus keta) skin hydrolysate prepared by various hydrolysis enzymes. The trypsin hydrolysate had the highest ACE inhibitory activity compared to the other hydrolysates. We attempted to isolate ACE inhibitory peptides from trypsin hydrolysate using chromatograph methods. The purified peptide was identified as Gly-Leu-Pro-Leu-Asn-Leu-Pro (M.W. 770 Da) and IC50 value was 18.7 μM. We synthesized ACE inhibitory peptides (Gly-Leu-Pro, Asn-Leu-Pro, Gly-Leu, and Leu-Pro) based on sequences of purified peptide from chum salmon skin. Among the synthesized peptides, the Gly-Leu-Pro had the highest ACE inhibitory activity. Furthermore, antihypertensive effect in spontaneously hypertensive rats also revealed that oral administration of synthesized ACE inhibitory peptide (Gly-Leu-Pro) can decrease systolic blood pressure significantly. Our study suggests that novel ACE inhibitory peptides derived from chum salmon skin may be beneficial as anti-hypertensive compounds for use as functional food ingredients.