GP13, an Arthrospira platensis cysteine desulfurase-derived peptide, suppresses oxidative stress and reduces apoptosis in human leucocytes and zebrafish (Danio rerio) embryo via attenuated caspase-3 expression

Abstract Arthrospira platensis (Ap) has several advantageous adaptive mechanisms including its efficient response to elevated oxidative stress (OS). This study intends to identify the antioxidant effect, in vitro and in vivo, of a novel peptide (GP13), Ap-derived cysteine-desulfurase (CDS) peptide, for antioxidant role and the associated mechanism(s) by which the GP13 elicits cytoprotection under elevated OS. Using bioinformatics tools, a short sequence of amino acids GP13 with a predicted antioxidant effect has been identified from the cysteine sulfurase domain of ApCDS between 243 and 616 amino acids. The synthesized GP13 peptide expressed significant antioxidant activity against free-radicals at various concentrations (10 - 80 µM), as established through the DPPH, ABTS, SARS, and HRS assays. Besides, GP13 demonstrated no cytotoxicity on Vero cells and human leucocytes. In H2O2-induced human leucocytes, the peptide exhibited maximum ROS scavenging activity at a concentration of 80 µM. Reduced apoptotic body formation was identified using Hoechst 33342 staining in GP13-exposed Vero cells. In vivo results revealed that pre-treated zebrafish larvae with GP13 (10 - 80 µM) ameliorated the H2O2-induced oxidative damage. Further, GP13 inhibited the H2O2-induced caspase-3-dependent apoptotic response at 96 hours post fertilized (hpf) zebrafish larvae. Together, results demonstrated that in GP13 treated (80 µM) zebrafish there was a reduction in the expression of lipid peroxidation level; and an increase in antioxidant-enzymes. Therefore, it is possible that GP13 peptide derived from ApCDS has in vitro and in vivo antioxidant activity and that GP13 should be further investigated for potential therapeutic utility in OS-mediated complications.