Comparative Antimicrobial Activity of Hp404 Peptide and Its Analogs against Acinetobacter baumannii

An amphipathic α-helical peptide, Hp1404, was isolated from the venomous gland of the scorpion Heterometrus petersii. Hp1404 exhibits antimicrobial activity against methicillin-resistant Staphylococcus aureus but is cytotoxic. In this study, we designed antimicrobial peptides by substituting amino acids at the 14 C-terminal residues of Hp1404 to reduce toxicity and improve antibacterial activity. The analog peptides, which had an amphipathic α-helical structure, were active against gram-positive and gram-negative bacteria, particularly multidrug-resistant Acinetobacter baumannii, and showed lower cytotoxicity than Hp1404. N-phenyl-1-naphthylamine uptake and DisC₃-5 assays demonstrated that the peptides kill bacteria by effectively permeating the outer and cytoplasmic membranes. Additionally, the analog peptides inhibited biofilm formation largely than Hp1404 at low concentrations. These results suggest that the analog peptides of Hp1404 can be used as therapeutic agents against A. baumannii infection.