Antimicrobial activity of novel symmetrical antimicrobial peptides centered on a hydrophilic motif against resistant clinical isolates: in vitro and in vivo analyses.

Antibiotic resistance poses a significant public health threat worldwide. The rise in antibiotic resistance and the sharp decline in effective antibiotics necessitate the development of innovative antibacterial agents. Based on the central symmetric structure of glycine-serine-glycine, combined with tryptophan and arginine, we designed a range of antimicrobial peptides (AMPs) that exhibited broad-spectrum antibacterial activity. Notably, AMP W5 demonstrated a rapid and effective sterilization against methicillin-resistant Staphylococcus aureus (MRSA), displaying both a minimum inhibitory concentration and a minimum bactericidal concentration of 8 µM. Mechanistic studies revealed that AMP W5 killed bacterial cells by disrupting the cytoplasmic membrane integrity, triggering leakage of cell contents. AMP W5 also exhibited excellent biocompatibility in both in vitro and in vivo safety evaluations. AMP W5 treatment significantly reduced skin bacterial load in our murine skin infection model. In conclusion, we designed a novel centrosymmetric AMP representing a promising medical alternative to conventional antibiotics for treating MRSA infections.

Importance: Increasing antibiotic resistance and the paucity of effective antibiotics necessitate innovative antibacterial agents. Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen causing bacterial infections with high incidence and mortality rates, showing increasing resistance to clinical drugs. Antimicrobial peptides (AMPs) exhibit significant potential as alternatives to traditional antibiotics. This study designed a novel series of AMPs, characterized by a glycine-serine-glycine-centered symmetrical structure, and our results indicated that AMP W5 exhibited a rapid and effective bactericidal effect against MRSA. AMP W5 also demonstrated excellent biocompatibility and a bactericidal mechanism that disrupted membrane integrity, leading to leakage of cellular contents. The notable reduction in skin bacterial load observed in mouse models reinforced the clinical applicability of AMP W5. This study provides a promising solution for addressing the increasing threat of antibiotic-resistant bacteria and heralds new prospects for clinical applications.