Hydrolysis of the chicken leg collagen led to angiotensin converting enzyme (ACE)-inhibitory activity, and feeding to hypertensive rats produced a 50 mmHg decrease in blood pressure, according to results published in the Journal of Agricultural and Food Chemistry.
ACE inhibitors work by inhibiting the conversion of angiotensin I to the potent vasoconstrictor, angiotensin II, thereby improving blood flow and blood pressure.
“Chicken collagen hydrolysate prepared in this study was composed of foods that can be easily incorporated into the daily diet,” wrote the authors from Nippon Meat Packers and Hiroshima University.
“It is important to prevent and improve hypertension, which is a lifestyle-related disease, in the course of daily life. By incorporating these foods into meals, normalization of blood pressure will be achieved without compromising the quality of life of those who need such foods.”
High blood pressure (hypertension),defined as having a systolic and diastolic blood pressure (BP) greater than 140 and 90 mmHg, is a major risk factor for cardiovascular disease (CVD) - a disease that causes almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year.
The researchers, led by Ai Saiko, extracted collagen from chicken legs and hydrolysed them using the Aspergillus oryzae protease enzyme. The ACE-inhibitory activity was determined in vitro.
Different fractions exhibited different activities, with the hydrolysate with a molecular-weight of 3000 Da (low fraction) possessing the strongest ACE-inhibitory activity.
The researchers used various techniques to characterize and identify the active proteins and peptides, and the active sequence was identified as Gly-Ala-Hyp-Gly-Leu-Hyp-Gly-Pro.
An in vivo study with spontaneous hypertensive rats revealed that the low fraction led to a decrease in blood pressure two hours administration. A significant decrease of 50 mmHg was observed after six hours, said the researchers.
“Single oral administration of low molecular-weight chicken collagen hydrolysates significantly lowered the blood pressure in spontaneous hypertensive rats, and long-term oral administration even suppressed the hypertension in these animals,” wrote the researchers.
“It is thought that ACE-inhibitory peptides or potent inhibitory peptides in chicken collagen hydrolysate show hypotensive activity through gastrointestinal digestion and absorption,” they added.
Source: Journal of Agricultural and Food ChemistryVolume 56, Pages 9586-9591, doi: 10.1021/jf072669w“Angiotensin I-Converting Enzyme-Inhibitory Peptides Obtained from Chicken Collagen Hydrolysate”Authors: A. Saiga, K Iwai, T. Hayakawa, Y. Takahata, S Kitamura, T. Nishimura, F. Morimatsu