Enzymatic optimization for enhancing earthworm peptide yields and biological activities on antioxidant, cytotoxic against HT-29 and HepG2 cancer cells, and antimigration

The purposes of this study were to investigate the antioxidant, cytotoxic against HT-29 and HepG2 cancer cells, and antimigratory activities of peptide fractions derived from Amynthas arenulus earthworm. Earthworm proteins were hydrolyzed with alcalase using response surface methodology. The optimal conditions resulted in a maximum degree of hydrolysis of 61.25% at an enzyme-to-substrate ratio of 1.5% (v/v) and a hydrolysis time of 2 h. Following simulated gastrointestinal digestion, gastric and intestinal recoveries of the peptides were 56.83% and 90.10%, respectively. The 10-30 kDa peptide fraction exhibited antioxidant activity, with estimated IC50 values of 3.18 and 0.79 mg/mL for DPPH and ABTS assays, respectively. FRAP activity was also exhibited. The 10-30 kDa peptide fraction showed antiproliferative activity against HT-29 and HepG2 cells, with IC50 values of 0.634 and 0.761 mg/mL, respectively, whereas it was not cytotoxic against non-cancerous cells of L929 fibroblast cells. This peptide fraction was trigger apoptosis-associated cellular changes observed using inverted light microscopy, AO/PI and DAPI staining, DNA fragmentation, and scanning electron microscopy. Relative cell migration values in HT-29 and HepG2 cells were 67.34% and 70.29%, respectively which compared to 100% of control. As resultants, this peptide fraction might be considered for applied in medical, nutraceutical food, and bioprocessing industries.