Indirect and direct damage to genomic DNA induced by 5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin upon photodynamic action

Photodynamic inactivation has been proposed as an efficient antimicrobial treatment for localized infections. Even though it is generally accepted that the cell wall and membrane components are the main targets of the photodynamic process, the importance of the nucleic acids as photodynamic targets is not yet fully understood. In this study, we investigated the photodamage of the genomic nucleic acids of the Gram negative bacterium Escherichia coli, using 5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin tri-iodide (Tri-Py+-Me-PF) as photosensitizing agent. We tested, for the first time, the indirect photodamage effects on genomic DNA extracted from photosensitized bacteria and compared it with the direct effects on genomic DNA extracted from non-photosensitized cells, treated in otherwise similar experimental conditions. The results suggest that DNA does not seem to be a major target of photodynamic inactivation, once direct exposure to photosensitization does not damage DNA and does ...