Neutralization of bacterial endotoxins by frog antimicrobial peptides

The ability of skin antimicrobial peptides of the southern bell frog, Litoria raniformis, to neutralize in vitro the endotoxin, proinflammatory lipopolysaccharide (LPS) complex, from two different gram-negative bacterial pathogens, human pathogen Escherichia coli (0111:B4) and frog pathogen Klebsiella pneumoniae, was investigated. The LPS neutralization activity of the natural mixture of skin antimicrobial peptides was measured using chromogenic Limulus amebocyte lysate assays. These skin antimicrobial peptides neutralized the LPSs from both pathogens at physiologically relevant concentrations (IC50 < 100 µg/mL) showing their potential for non-specific LPS neutralization in vivo in the skin of infected frogs and for development of anti-endotoxin agents.