Functional properties and biological activities of peptides from zebra blenny protein hydrolysates fractionated using ultrafiltration

Zebra blenny (Salaria basilisca) protein hydrolysates (ZBPH-Z) were prepared by treating zebra blenny muscles with crude alkaline protease extract from the same species. Hydrolysates were separated according to molecular weight (MW), using ultra-filtration membranes, into 5 fractions (MW > 30, 10 < MW < 30, 5 < MW < 10, 1 < MW < 5, and MW < 1 kDa, referred as F1, F2, F3, F4, and F5, respectively). Peptide fractions were analysed using reversed-phase high-performance liquid chromatography (RP-HPLC). They contained high amount of peptides with hydrophilic character. All peptide fractions had good solubility and had interfacial properties, which were correlated with concentrations and peptide lengths. Peptide fractions showed, to a variable extent, high concentration-dependent antioxidant activity in vitro. F2 showed the highest antioxidant activities. Furthermore, F1 showed the most alpha-amylase inhibitory activity with IC50 of 71 mu g/ml. F1 had the highest prolongation of both the prothrombin time and the activated partial thromboplastin time.