Preparation And Purification Peptides From Spirulina Protein And Their Antioxidative In Different Oxidation Systems

Bioactive peptides from enzymatic hydrolysis of various food proteins such as soy protein, casein, whey protein, gelatin and wheat gluten have been shown to possess antioxidative activity. Oxidative stress is an important factor in the genesis of many diseases, such as cancer, cardiovascular and degenerative diseases.Many synthetic antioxidants such as butylated hydroxyanisole (BHA), Butylated hydroxytoluene(BHT) have been used to retard the oxidation process; however, the use of synthetic antioxidants must be under strict regulation due to potential health hazards.Therefore, the search for natural antioxidants as alternatives is therefore of great interest among researchers.In this study, Alcalase protease was used to hydrolyze the protein extracts of spirulina to produce polypeptides. The effects of pH, enzyme dosage, hydrolysis time and temperature on degree of hydrolysis were investigated through single factor tests respectively, and these factors were optimized through response surface methodology (RSM) that was designed based on Box-Behnken central combination. The optimum hydrolysis conditions are as follows:pH=7, enzyme dosage(ratio of enzyme to substrate)4300U/g, hydrolysis temperature 55℃and time 160 min.The hydrolysates of spirulina protein were ultrafiltrated with 5 kD hollow fiber ultrafiltration membrane was collected and then purified through SephadexG-25 column chromatography with PBS (pH=7) as eluent. Low molecular weights Peptides were collected, whose molecular weight range is from 307 Da to 1450 Da determined by standard proteins.In this paper, the crude extract from spirulina platensis was digested by enzymes, and then the biological function of their hydrolysates was assayed. Results indicated that the antioxidant activities of the hydrolysate were enhanced. A potent antioxidative was separated and isolated.The peptides could efficiently quench a variety of free radicals,including hydroxyl radical, super-oxide radical, peroxyl radical,DPPH radical and ABTS radicals, and performed more efficiently than that observed for BHT, ascorbic acid.These results demonstrate that inexepensive algae protein could be a new alternative to produce antioxidative peptides.