Porphyrins containing basic aliphatic amino groups as potential broad-spectrum antimicrobial agents

Synthesis and properties of porphyrins bearing basic amine and pentafluorophenyl groups as photosensitizer to inactivate Staphylococcus aureus, Escherichia coli and Candida albicans. [Display omitted] •New porphyrins containing pentafluorophenyl and basic amine groups were synthetized.•The basic aliphatic amino groups can be protonated at physiological pH.•High affinity was found between F5APP and the microbial cells.•F5APP was highly effective as a broad-spectrum antimicrobial photosensitizer.•These porphyrins appear to act as photosensitizers mainly via the intermediacy of O2(1Δg). New porphyrin derivatives bearing basic aliphatic amino groups were synthesized from the condensation of meso-4-[(3-N,N-dimethylaminopropoxy)phenyl]dipyrromethane, pentafluorobenzaldehyde and 4-(3-N,N-dimethylaminopropoxy)benzaldehyde. The reaction was catalyzed by trifluoroacetic acid in acetonitrile. This approach was used to obtain porphyrins with different patterns of substitution, of which three of them were isolated: 5,15-di(4-pentafluorophenyl)-10,20-di[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (F10APP), 5-(4-pentafluorophenyl)-10,15,20-tris[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (F5APP) and 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (TAPP). The UV–vis spectroscopic characterizations and the photodynamic effect of these compounds were compared in N,N-dimethylformamide. These porphyrins showed red fluorescence emission with quantum yields of 0.09-0.15. Moreover, they sensitized the production of singlet molecular oxygen, reaching quantum yields values of 0.33-0.53. Photodynamic inactivation was studied in two bacteria, Staphylococcus aureus and Escherichia coli, and a yeast Candida albicans. High amount of cell-bound porphyrin was obtained at short times (