Functional characterization of Cr-CATHs: Novel antimicrobial peptides from the coastal bird Chroicocephalus...

The escalating global threat of antimicrobial resistance (AMR) and chronic biofilm-associated infections underscores the urgent need for novel therapeutic agents. Antimicrobial peptides (AMPs) offer a promising alternative due to their potent activity, broad-spectrum efficacy, and low resistance induction. In this study, we identified three novel cathelicidin-like peptides-Cr-CATH-1 (Cr1), Cr-CATH-2 (Cr2), and Cr-CATH-3 (Cr3)-from Chroicocephalus ridibundus. These peptides were systematically evaluated for their physicochemical properties, antimicrobial activity, bactericidal kinetics, and effects on biofilm formation and persister cells. Cr1 exhibited the most potent and broad-spectrum antimicrobial activity, particularly against Gram-negative and aquatic pathogens. Although Cr2 and Cr3 displayed relatively weaker antimicrobial effects, both peptides were effective in biofilm eradication and persister cell killing. Cr1 also demonstrated strong bactericidal activity, low cytotoxicity, and minimal hemolysis, suggesting a favorable safety profile. Its stability under physiological salt conditions, along with its ability to disrupt bacterial membranes, bind to DNA, and induce reactive oxygen species (ROS) production, highlights its therapeutic potential. In vivo, Cr1 significantly reduced bacterial load and improved survival in a murine peritonitis model, further supporting its potential for clinical and aquaculture applications. Our results suggest that Cr1 is a promising candidate for further development, while Cr2 and Cr3 may provide valuable insights for targeted therapeutic strategies, warranting additional investigation.