Bioactive peptides from Spirulina-phycocyanin extract

Phycocyanin is one of bioactive compounds rich in cyanobacteria especially Arthrospira (Spirulina) platensis. It has been used as a nutritional supplement due to its potential biological activities e. g. antimicrobial, antioxidant, antitumor and antidiabetic. Therefore, this study aims to increase commercial value of phycocyanin as functional ingredients in food, pharmaceutical and cosmetic industry by identification of bioactive peptides from Spirulina-phycocyanin extract and examined the target biological activities. Phycocyanin peptides, prepared by using pepsin/trypsin digestion and subsequently analyzed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS), exhibit various biological properties, including ACE inhibitor, dipeptidyl peptidase (DPP)-IV inhibitor, antimicrobial and antioxidative activity. The antimicrobial activity of phycocyanin peptides, obtained from pepsin and trypsin digestion, were determined by disk diffusion method. The results showed that five selected bacteria i. e. Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica and Klebsiella pneumoniae, were susceptible to inhibition by phycocyanin peptides derived from pepsin digestion. The disk diffusion tests indicated that 180 µg protein of phycocyanin peptide derived from pepsin digestion showed inhibition zones of 8-10 mm for S. aureus, P. aeruginosa, S. enterica and K. pneumonia. However, these bacterial strains demonstrated resistance to phycocyanin peptides derived from trypsin digestion. Furthermore, the DPP- IV inhibitory properties and antioxidative activity of phycocyanin peptides were also examined.