Inhibitions of renin and angiotensin converting enzyme activities by enzymatic chicken skin protein hydrolysates

- Degree of hydrolysis was directly correlated to peptide yield of protein hydrolysates.
- Alcalase digestion produced protein hydrolysates with high ACE-inhibitory activity.
- Pepsin + pancreatin digestion gave protein hydrolysates with high renin inhibition.
- Peptide size was inversely related to ACE but not renin inhibitory activity.

Enzymatic hydrolysates from chicken skin protein were investigated for their in vitro inhibitions of angiotensin converting enzyme (ACE) and renin activities. Enzyme hydrolysis of the chicken skin protein from the thigh and breast muscles was done using alcalase or a combination of pepsin/pancreatin (PP) at enzyme concentrations of 1-4%. The chicken skin protein hydrolysates (CSPH) were then fractionated by membrane ultrafiltration into different molecular weight peptides (< 1, 1-3, 3-5 and 5-10 kDa). Results showed that degree of hydrolysis (DH) of the hydrolysates increased significantly with protease concentration for all the samples (72.61-81.88%) and correlated positively with peptide yield. The alcalase hydrolysates generally had significantly higher (p < 0.05) ACE-inhibitory activity when compared to PP hydrolysates. ACE inhibition was inversely related to size of ultrafiltration membrane peptides. A moderate renin-inhibitory activity was observed (15-36%), which was dependent on the type of protease; the PP hydrolysates showed significantly higher (p < 0.05) inhibition than alcalase hydrolysates. These results suggest that CSPH can be considered a potential ingredient for the development of functional foods and nutraceuticals that can attenuate catalytic activities of ACE and renin.