Antioxidant and Antimicrobial Activities of Peptide Fractions Derived from Enzymatic Digestion of Desmodesmus sp. Protein Extract

Cyanobacteria and microalgae are promising sources of valuable bioactive compounds for nutraceutical and pharmaceutical applications. Proteins and peptides derived from these microorganisms have been shown different biological actions, including antioxidant and antimicrobial activities. In this study, Desmodesmus sp. protein extract was digested using two proteases, including bacterial protease with optimum activity in alkaline conditions and pepsin with optimum activity in acidic pH. The peptide mixtures derived from protease hydrolysis were evaluated by DPPH assay for antioxidant activity and microdilution antimicrobial assay. The results showed that peptides derived from both pepsin and bacterial protease digestions enhanced the antioxidant activity and these samples had between 80-100% antioxidant activities. In addition, pepsin digestion could reduce the MIC against S. aureus and methicillin-resistant S. aureus (MRSA) twofold compared to the initial protein extract before digestion. In conclusion, the peptides derived from enzymatic digestion of Desmodesmus sp. protein extract had promising biological activities that need further studies to identify the most bioactive peptide.