Angiotensin I-Converting Enzyme-Inhibitory Peptides Obtained from Chicken Collagen Hydrolysate

• Published in: Journal of agricultural and food chemistry 2008-10, Vol.56 (20), p.9586-9591
• Main Authors: Saiga, Ai, Iwai, Koji, Hayakawa, Toru, Takahata, Yoshihisa, Kitamura, Shiniich, Nishimura, Toshihide, Morimatsu, Fumiki
• Format: Article
• Language: English
• Subjects: amino acid sequences; Angiotensin I-converting enzyme inhibitor; Angiotensin-Converting Enzyme Inhibitors - chemistry; Angiotensin-Converting Enzyme Inhibitors - isolation & purification; Angiotensin-Converting Enzyme Inhibitors - pharmacology; animal models; Animal productions; Animals; Antihypertensive Agents - chemistry; Antihypertensive Agents - isolation & purification; Antihypertensive Agents - pharmacology; antihypertensive effect; Biological and medical sciences; Blood Pressure; chicken collagen; chicken meat; Chickens; collagen; Collagen - chemistry; Collagen - isolation & purification; Collagen - pharmacology; enzyme inhibition; Food Chemistry/Biochemistry; Food industries; fractionation; Fundamental and applied biological sciences. Psychology; human diseases; human nutrition; hypertension; hypotensive activity; Male; Mass Spectrometry; molecular sequence data; molecular weight; peptide; peptides; Peptides - chemistry; Peptides - isolation & purification; Peptides - pharmacology; peptidyl-dipeptidase A; Peptidyl-Dipeptidase A - metabolism; protein hydrolysates; Protein Hydrolysates - chemistry; Protein Hydrolysates - isolation & purification; Protein Hydrolysates - pharmacology; Rabbits; Rats; Rats, Inbred SHR; spontaneously hypertensive rats; Terrestrial animal productions; ultrafiltration; Vertebrates
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf072669w

In this study, collagen extracted from chicken legs (which are the yellow keratin parts containing a nail) was hydrolyzed with various enzymes, and the angiotensin I-converting enzyme (ACE)-inhibitory activity of each hydrolysate was determined. The hydrolysate by treatment with an Aspergillus species-derived enzyme had the highest activity (IC50 = 260 µg/mL). The fraction of this hydrolysate obtained by ultrafiltration with a molecular-weight cutoff of 3000 Da (low fraction) had a stronger activity (IC50 = 130 µg/mL) than the fractionated one. This fraction was further fractionated by HPLC, and the peptides in the fraction with high ACE-inhibitory activity were identified. The amino acid sequences of the four peptides were identified using a protein sequencer. These peptides were synthesized to confirm their ACE-inhibitory activities; this showed that peptides with a Gly-Ala-Hyp-Gly-Leu-Hyp-Gly-Pro sequence had the highest activity (IC50 = 29 µM). When the low fraction was administered to spontaneous hypertensive rats, a decrease in their blood pressure was observed after 2 h of administration, and a significant decrease in blood pressure (−50 mmHg) was observed after 6 h. Moreover, long-term administration studies indicated that the low fraction showed a significant suppression of increased blood pressure.