Purification and Characterization of Antioxidant Peptides from Ark Shell (Scapharca subcrenata) Hydrolysates by Pepsin Hydrolysis

Abstract

In this present study, two bioactive octapeptides with antioxidant activity were derived from the ark shell (Scapharca subcrenata) peptic hydrolysates. Ark shell protein hydrolysates (ASPH) was prepared with enzyme to substrate (E/S) ratio of 1:100 and 1:500 for 0.5, 1, 2 and 4 hr. The hydrolysates which was generated at E/S ratio of 1:100 with 1 hr displayed the highest oxygen radical absorbance capacity (ORAC value=368.51 µM TE/mg ASPH). Thus, it was separated and purified by using SuperdexTM Peptide 100/300 GL and reversed-phase high performance liquid chromatography (RP-HPLC) on Hypersil GOLD column. After peptide fractions with the optimal antioxidant activity were selected through DPPH assay, antioxidant peptides were identified as QTOF-LC-MS/MS analysis by S1 (HPLDSLCL, 897.06 Da) and S2 (MCLDSCLL, 897.15 Da). Two antioxidant peptides were synthesized by SPPS and measured antioxidant activity comparing with the positive control glutathione (GSH). S1, S2 and GSH exhibited DPPH radical scavenging activity (IC50=74.36 µM, 19.47 µM and 19.31 µM), ABTS+ radical scavenging activity (778.86 µM TE/mM S1, 678.36 µM TE/mM S2 and 893.42 µM TE/mM GSH) and ORAC value (209.81 µM TE/mM S1, 333.91 µM TE/mM S2 and 239.13 µM TE/mM GSH), also reducing power activity (absorbance at 750nm=0.067, 0.29 and 0.19). In a result, these peptides have the potent antioxidant activity and show non-cytotoxicity on hepatocytes. Therefore, antioxidant peptides derived from ASPH can be useful ingredients for various pharmaceutical and nutraceutical applications.