Investigations on novel aedesin-derived peptides against ESKAPE pathogens

Abstract

Antimicrobial peptides (AMPs) are promising alternatives to conventional antibiotics, yet strategies to optimize novel peptide templates remain limited. In this study, aedesin, a cecropin-like peptide from Aedes aegypti, was investigated and found to adopt a helix-bend-helix structure. Systematic modifications were introduced on the N- or C-terminal helices to enhance antimicrobial efficiency and selectivity. N-terminal derivatives showed greater potency compared to C-terminal modifications. Notably, peptides 2D11 and 2D12 exhibited minimum inhibitory concentrations (MICs) of 8-16 μg/mL against Acinetobacter baumannii, while peptide 3E1-E3 displayed broad-spectrum activity against ESKAPE pathogens with MICs of 16-64 μg/mL. Similarly, peptides 4B8-B11 demonstrated MICs of 8-32 μg/mL against most bacteria, excluding Enterococcus faecium. Among them, peptide 4B11 showed the strongest activity against methicillin-resistant Staphylococcus aureus (MRSA) strain MW2, with an MIC of 8 μg/mL. Cytotoxicity assays confirmed that the peptides were non-toxic to HEPG2 cells at their MICs and to human red blood cells up to 128 μg/mL. Mechanistic studies revealed a membrane-disruptive mode of action, supported by propidium iodide uptake and membrane depolarization assays. Furthermore, peptides effectively eliminated antibiotic-induced persister cells and protected Galleria mellonella from MRSA infection. These findings highlight optimized aedesin-derived peptides as potential candidates against ESKAPE pathogens.