Abstract
Superoxide dismutase (SOD) is an evolutionary conserved detoxification enzyme and powerful antioxidant which defends against the elevated ROS that are induced by various stresses. Arthrospira platensis (Ap) is known for its antioxidant-mediated immunostimulant properties, but there is no report on the SOD dependent antioxidant mechanism. Therefore, in this study, we have analysed the effect of H2O2 on growth and pigment composition in spirulina. Results showed that spirulina exposed to 10 mM H2O2 showed elevated growth pattern as well as increase in chlorophyll pigment composition especially during early days of exposure. Gene expression results showed that the expression profile of ApSOD during oxidative stress stimulated by 10 mM H2O2 at different time intervals (0, 5, 10, 15 and 20 days) with highest expression on day 10 post-exposure. Together, the results confirmed the antioxidant role of ApSOD in spirulina during oxidative stress induced by H2O2. Based on the amino acid arrangement and composition, we have predicted a short peptide 160LGLDVWEHAYYL171 (LL12) from the catalytic centre of C-terminal SOD domain; further the peptide was synthesized. Antioxidant assays showed that LL12 peptide critically involved in radical scavenging mechanism. Also, LL12 peptide reduced the intracellular ROS level in H2O2 exposed leucocytes at a concentration of 12.5 μM. Cytotoxicity assay was performed on human leucocytes which showed that LL12 did not exhibit any cytotoxic activity against any of the leucocytes population. Overall, the study highlights the radical scavenging property of a novel short peptide derived from the C-terminal domain of ApSOD which have the potential to develop as a biopharmaceutical drug.
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•A full-length superoxide dismutase identified from de novo transcriptome of A. platensis.•Expression of ApSOD mRNA is increased at 10 mM H2O2 stressed Spirulina.•A novel short peptide (LL12) derived from the C-terminal domain of ApSOD enzyme.•LL12 reduced the intracellular ROS level in H2O2 exposed human blood leucocytes.•No significant cytotoxicity was induced by LL12 in blood cells.