His-His-Leu, an angiotensin I converting enzyme inhibitory peptide derivedfrom Korean soybean paste, exerts antihypertensive activity in vivo

It has been reported that soybean peptide fractions isolated from Korean fe rmented soybean paste exert angiotensin I converting enzyme (ACE) inhibitor y activity in vitro. In this study, further purification and identification of the most active fraction inhibiting ACE activity were performed, and it s antihypertensive activity in vivo was confirmed. Subsequently, a novel AC E inhibitory peptide was isolated by preparative HPLC. The amino acid seque nce of the isolated peptide was identified as His-His-Leu (HHL) by Edman de gradation. The IC50 value of the HHL for ACE activity was 2.2 mug/mL in vit ro. Moreover, the synthetic tripeptide HHL (spHHL) resulted in a significan t decrease of ACE activity in the aorta and led to lowered systolic blood p ressure (SBP) in spontaneously hypertensive (SH) rats compared to control. Triple injections of spHHL, 5 mg/kg of body weight/ injection resulted in a significant decrease of SEP by 61 mmHg (p < 0.01) after the third injectio n. These results demonstrated that the ACE inhibitory peptide HHL derived f rom Korean fermented soybean paste exerted antihypertensive activity in viv o.