Purification and characterization of antioxidant peptides from enzymatically hydrolyzed ark shell ( Scapharca subcrenata )

Information of bioactive peptides derived from ark shell is seldom reported. In this study, ark shell was hydrolyzed by pepsin with enzyme to substrate (E/S) ratios of 1:100 and 1:500 for 1–4 h. Ark shell hydrolysates (ASHs) were subjected to evaluate their antioxidant activities by free radical scavenging and oxygen radical absorbance capacity (ORAC) assays. Antioxidant peptides (P) were purified and identified as MCLDSCLL (P1) and HPLDSLCL (P2). P1 and P2 showed potent antioxidant activities with IC50 value of 19.47 ± 0.35 and 74.36 ± 0.54 μM, and glutathione (GSH), as positive control, showed 19.31 ± 0.36 μM against DPPH radical. P1 and P2 exhibited 678.36 ± 5.33 μM trolox equivalent (TE)/mM P1 and 778.86 ± 9.64 μM TE/mM P2 against ABTS+ radical scavenging, and ORAC values of 333.91 ± 26.05 μM TE/mM P1 and 209.81 ± 21.74 μM TE/mM P2. P1 and P2 also showed strong reducing power. In addition, P2 strongly inhibited copper-catalyzed human LDL oxidation.