Radical scavenging property of a novel peptide derived from C-terminal SOD domain of superoxide dismutase enzyme in Arthrospira platensis

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 H(2)O(2 )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 byH(2)O(2). Based on the amino acid arrangement and composition, we have predicted a short peptide (160)LGLDVWEHAYYL(171) (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 mu M. 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.