Resistance to gastrointestinal proteases of the short chain peptides having reductive effect in blood pressure

The peptides with average molecular weight 315 were prepared from sardine proteins by Bacillus licheniformis alkaline proteases. The short chain peptides had no bitter taste and little fish flavor. The short chain peptides showed the potent angiotensin I-converting enzyme (ACE) inhibitory activity, which was high resistance to the hydrolysis by any digestive proteases. ACE inhibitory activity of short chain peptides didn't change by the pig intestinal fluid after pepsin digestion. Compared with the long chain peptides in sardine muscle hydrolyzate prepared by digestive proteases, inhibitory activities of various digest were weaker than that of the short chain peptides derived from alkaline proteases hydrolyzate. The short chain peptides were assayed in spontaneously hypertensive rats and found to reduce on blood pressure.