Synthesis, Spectroscopic and Photophysical Characterization and Photosensitizing Activity Toward Prokaryotic and Eukaryotic Cells of Porphyrin-Magainin and –Buforin Conjugates

Cationic antimicrobial peptides (CAMPs) and photodynamic therapy (PDT) are attractive tools to combat infectious diseases and to stem further development of antibiotic resistance. In an attempt to increase the efficiency of bacteria inactivation, we conjugated a PDT photosensitizer, cationic or neutral porphyrin, to a CAMP, buforin or magainin. The neutral and hydrophobic porphyrin, which is not photoactive per se against Gram-negative bacteria, efficiently photoinactivated E. coli after conjugation to either buforin or magainin. Conjugation to magainin resulted in the considerable strengthening of the cationic and hydrophilic porphyrin’s interaction with the bacterial cells as shown by the higher bacteria photoinactivation activity retained after bacterial suspension washings. The porphyrin-peptide conjugates also exhibited strong interaction capability as well as photoactivity toward eukaryotic cells, namely human fibroblasts. These findings suggest therefore that these CAMPs have the potential to carry drugs and other types of cargoes inside mammalian cells similarly to cell-penetrating peptides.