Antibacterial peptide mostly active against Gram-positive bacteria (MIC=0.24 ug/ml on Bacillus subtilis, and MIC=0.94 ug/ml on Micrococcus luteus, MIC>120 ug/ml on both Escherichia coli and Pseudomonas aeruginosa). Two peptides derived from the C-terminal region have been synthesized. The peptide Os consist of residues 16-37, while the peptide Os-C is an analog in which the three cysteine residues are omitted. Both peptides show potent bactericidal activity, and high antioxidant activity. Belongs to the invertebrate defensin family.