Antioxidant peptides from freshwater clam extract using enzymatic hydrolysis

The enzymatic hydrolysate of freshwater clam (Corbicula fluminea) extract was prepared using commercially available proteases. The antioxidant activity of the hydrolysate was evaluated by reducing power and 2,2’-azinobis-3-ethylbenzothiazoline-6-sulfonic acid free radical decolorization assays. The hydrolysate, especially its fraction purified by gel filtration, had a good antioxidant activity. The Trolox equivalent antioxidant capacity of the fraction with the highest radical scavenging ability reached 158.04 ± 2.43 μg/mg, which was sevenfold higher than that of the original hydrolysate. Molecular weight distribution analysis revealed that peptides over 1000 Da in the hydrolysate had better abilities to donate electrons, whereas peptides below 1000 Da more effectively eliminated radicals. Therefore, peptides from freshwater clam extract could be employed as potential natural antioxidants, performing their activities via different mechanisms. Key words: Antioxidant peptides, freshwater clam extract, enzymatic hydrolysate, molecular weight distribution.