Abstract:
Recently, many studies have been focusing on the characterisation of bioactive peptides derived from natural sources. Collagen is a highly valuable product important in cosmetic, pharmaceutical and food industry. Commercially, collagen is extracted mainly from either bovine or porcine. However, due to religious restrictions and widespread diseases including bovine spongiform encephalopathy (BSE), transmissible spongiform encephalopathy (TSE) and foot and mouth disease (FMD), alternative sources of collagen such as poultry and fish are more desirable. Chicken feet thus is a promising alternative collagen source to replace beef or pork collagen. Peptides obtained by hydrolysis of collagen are known to have a number of useful bioactive properties and may replace synthetic peptides that may cause side effects after oral administration, in the treatment of high blood pressure and other cardiovascular diseases. Therefore, the aim of this study was to isolate bioactive peptides from collagen extracted from chicken (Gallus domesticus) feet through proteolytic hydrolysis and to determine the bioavailability of collagen hydrolysates in terms of Angiotensin I-converting enzyme (ACE) inhibitory activities, antioxidant radical scavenging activities, and antimicrobial activity using three different proteases namely, pepsin, trypsin, and alcalase. In this study, the highest ACE inhibitory activity was observed in a peptide purified from chicken feet collagen after 12 hours of hydrolysis with alcalase (CH-A12) yielding IC50 of 30.11 μg/mL. Similarly, the highest antioxidant activity was also found in the hydrolysate produced by alcalase after 2 hours (CH-A2), which yielded the highest DPPH and ABTS radical scavenging activities of 20.63±0.09 and 32.26±0.32 μM Trolox/mg sample, respectively. The activities then decreased after sequential purification processes indicating that there were synergistic effects between the fractions in the unpurified hydrolysate. However, the most active antimicrobial activity was observed in the gel-filtration fraction obtained from collagen treated with pepsin for 4 hours (CH-P4) against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538 with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 10 mg/mL while no positive activity was observed against Candida albicans. These results therefore suggest that peptides obtained from chicken feet collagen treated with either alcalase or pepsin could serve as natural alternative sources for the therapeutic applications in the treatment of high blood pressure as well as nutraceutical and food preservation applications.