Determination of antioxidant and chelating activity of protein hydrolysates from Spirulina (Arthrospira maxima) obtained by simulated gastrointestinal digestion

Spirulina is a cyanobacteria that has been used as food since ancient times, for example in Mexico it was consumed by the Aztecs. Its high protein content, distribution and amino acid composition suggests the presence of important peptides encrypted within the sequences of parent proteins, that after been released by digestive process they could show an antioxidant effect. Our present study examined the above hypothesis through the determination of the antioxidant and chelating activity of two Spirulina samples (SpRPh: Spirulina reduced of pholyphenols and PCBEx: extract of phycobiliproteins), subjected both to sequential hydrolysis with pepsin and pancreatin. At the end of the enzymatic action, extensive hydrolysates with a degree of hydrolysis (% DH) of 31.4 and 36.7%, for SpRPh and PCBEx respectively, were obtained. By determining the electrophoretic profiles, the degradation of characteristic bands of Spirulina proteins and the release of smaller peptides were observed. As a general trend, the antioxidant activity determined by different methods improved after simulating gastrointestinal digestion. On the other hand, protein hydrolysates from both groups showed Cu2+ and Fe2+ chelating; activity.