Engineered N-terminal modified α/β-hybrid peptides with enhanced selectivity and stability: Multi-target antibacterials for combating MRSA.

Cytotoxicity, hemolytic effects, poor enzymatic stability and high manufacturing costs are the major challenges associated with the clinical development of antibacterial peptides. We designed and synthesized a new series of short cationic α/β-hybrid peptides (TH-01, TH-02, and TH-03) by incorporating a urea bond in place of a traditional amide bond and an N-terminal THPA moiety. These modifications were strategically incorporated to enhance antibacterial activity, structural stability, and cellular selectivity, also allowing detailed mechanistic investigation. Remarkably, the synthesized peptides retained antimicrobial activity, achieving an MIC of 1.5-12.5 μM (0.9-7.5 μg/ml) against MRSA, along with enhanced selectivity and stability. The subsequent mechanistic studies revealed that these peptides showed bactericidal activity by utilizing multi-targeted mechanisms, including lysis of the cell membrane, interaction with genomic DNA and induction of reactive oxygen species. Overall, this class of α/β-hybrid peptides represents a promising advancement toward the development of short, stable, and selective antimicrobial agents, offering valuable new strategies for combating antimicrobial resistance.