This research study investigated the
free radical-scavenging activities of
peptides which were obtained from the
protein hydrolysates of the spotted babylon snail using a combination of
pepsin and
pancreatin proteolysis which can replicate the conditions of gastrointestinal digestion. In this study, spotted babylon
protein hydrolysate (SPH) derived from a sequential 3 hour digestion, first with
pepsin and then with
pancreatin, was examined. SPH was fractionated using molecular weight cut-off membranes for 10 kDa, 5 kDa, 3 kDa, and 0.65 kDa. It was found that the MW < 0.65 kDa fraction provided the greatest levels of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic
acid (
ABTS), 2,2-diphenyl-1-picrylhydrazl (DPPH), and
nitric oxide (NO) radical scavenging activity. Three subfractions of the MW < 0.65 kDa fraction were then generated via RP-HPLC. The subfraction which subsequently demonstrated the greatest
free radical scavenging activity was F3, which was accordingly chosen for further investigation commencing with quadrupole-time-of-flight-electron spin induction-mass spectrometry-based de novo
peptide sequencing. This resulted in the identification of a pair of novel
peptides: His-Thr-Tyr-His-Glu-Val-Thr-Lys-His (HTYHEVTKH), and
Trp-Pro-
Val-Leu-
Ala-Tyr-
His-Phe-Thr (WPVLAYHF). The WPVLAYHF
peptide exhibited greater
antioxidant activity. The study also confirmed that the F3 sub-fraction was able to prevent
hydroxyl radicals from causing DNA damage by conducting tests which involved the pKS, pUC19, and pBR322 plasmids using the Fenton reaction. In addition, cellular
antioxidant activity was demonstrated by two synthetic
peptides toward the human
adenocarcinoma colon (Caco-2) cell line, with the potency of the activity dependent upon the
peptide concentration.