Antimicrobial potential of Protoporhyrin IX-antimicrobial peptide conjugates against Pseudomonas aeruginosa

The combination of photosensitizers and antimicrobial peptides (AMPs) enhances the efficacy of antimicrobial photodynamic inactivation (aPDI). In this study, we evaluated the activity of Protoporphyrin IX and two AMPs—CAMEL and Pexiganan—including their conjugates. The reference strain Pseudomonas aeruginosa ATCC 10145 was used. Photoinactivation experiments were conducted for the photosensitizer (PS) alone, the mixture of PS and AMPs, and their conjugates. PS accumulation was assessed, and the potential for resistance development was evaluated. The findings confirm that AMPs can enhance PS uptake into bacterial cells. Moreover, the Protoporphyrin IX–Pexiganan conjugate was the most effective in aPDI. Further evaluation demonstrated that this compound does not induce resistance development. This study highlights the effectiveness of this approach. The synergy between Pexiganan and Protoporphyrin IX against P. aeruginosa was confirmed. Further research is needed to assess the efficacy of the tested compound against other bacterial strains.