Enhanced Antibacterial, Anti-Inflammatory, and Antibiofilm Activities of Tryptophan-Substituted Peptides Derived from Cecropin A-Melittin Hybrid Peptide BP100

The emergence of multidrug-resistant pathogens necessitates the development of novel antimicrobial agents. BP100, a short α-helical antimicrobial peptide (AMP) derived from cecropin A and melittin, has shown promise as a potential therapeutic. To enhance its efficacy, we designed and synthesized 16 tryptophan-substituted BP100 analogs based on helical wheel projections. Among these, BP5, BP6, BP8, BP11, and BP13 exhibited 1.5- to 5.5-fold higher antibacterial activity and improved cell selectivity compared to BP100. These analogs demonstrated superior efficacy in suppressing pro-inflammatory cytokine release in LPS-stimulated RAW 264.7 cells and eradicating preformed biofilms of multidrug-resistant <i>Pseudomonas aeruginosa</i> (MDRPA). Additionally, these analogs showed greater resistance to physiological salts and serum compared to BP100. Mechanistic studies revealed that BP100 and its analogs exert their antibacterial effects through membrane disruption, depolarization, and permeabilization. Notably, these analogs showed synergistic antimicrobial activity with ciprofloxacin against MDRPA. Our findings suggest that these tryptophan-substituted BP100 analogs represent promising candidates for combating multidrug-resistant bacterial infections, offering a multifaceted approach through their antibacterial, anti-inflammatory, and antibiofilm activities.