Recovery and identification bio-active peptides from protein isolate of Spirulina platensis and their in vitro effectiveness against oxidative stress-induced erythrocyte hemolysis.

BACKGROUND Spirulina platensis is recognized as one of the most nutritious foods, containing a high protein content of up to 70%. Meanwhile, he interest in using natural protein resources to develop bioactive peptides is steadily increasing. Therefore, this study released the bioactive peptides from S. platensis by enzymatic hydrolysis using pepsin (1:3000 U g(-1)), and their amino acid sequences were determined by de novo sequencing. On this basis, the antioxidant activities of synthesized bioactive peptides were comprehensively evaluated by 2,2 '-azinobis-3-ethylbenzothiazolin-6-sulfonic acid assay, 1,1-diphenyl-2-picryhydrazyl assay, and cell hemolysis assay induced by 2,2 '-azobis-(2-amidino-propane) dihydrochloride (AAPH). RESULTS The degree of hydrolysis and recovery percentage of pepsin hydrolysis were 172 and 825 g kg(-1) respectively, and FFEFF (P1: m/z 736.4, 8%), EYFDALA (P2: m/z 828.4, relative intensity 18.5%), and VTAPAASVAL (P3: m/z 899.5, relative intensity 17.3%) were purified and identified. P2 possessed an excellent radical scavenging activity compared with P1, P3, and vitamin C, which was contributed to by its high beta-sheet conformation and specific amino acid compositions. Moreover, P2 significantly attenuated AAPH-induced oxidative hemolysis of erythrocytes and protected the erythrocytes, because it reduced the formation of malondialdehyde and increased the enzyme activities of superoxide dismutase, catalase, and glutathione peroxidase in erythrocytes. CONCLUSION This study provided insights into the potential antioxidant function of the synthesized peptides originated from the bioactive peptides of S. platensis proteins, which would contribute to the development of natural antioxidant from new protein resources. (c) 2020 Society of Chemical Industry