Can Corrole Dimers Be Good Photosensitizers to Kill Bacteria?

Abstract

Corroles possess key photophysical and photochemical properties to be exploited as therapeutic agents in antimicrobial photodynamic therapy (aPDT). Herein, we present for the first time the antimicrobial efficiency of three corrole dimers and of the corresponding precursor against the Gram(+) bacterium Staphylococcus aureus. Additionally, to explore future clinical applications, the cytotoxicity of the most promising derivatives towards Vero cells was evaluated. The aPDT assays performed under white light irradiation (50 mW/cm2; light dose 450 J/cm2) and at a corrole concentration of 15 µM showed that some dimers were able to reduce 99.9999% of S. aureus strain (decrease of 5 log10 CFU/mL) and their photodynamic efficiency was dependent on position, type of linkage, and aggregation behavior. Under the same light conditions, the corrole precursor 1 demonstrated notable photodynamic efficiency, achieving total photoinactivation (>8.0 log10 CFU/mL reduction) after the same period of irradiation (light dose 450 J/cm2). No cytotoxicity was observed when Vero cells were exposed to corrole 1 and dimer 3 for 24 h according to ISO guidelines (ISO 10993-5) for in vitro cytotoxicity of medical devices. The results show that corrole dimers, dependent on their structures, can be considered good photosensitizers to kill Staphylococcus aureus.

Reaction of Corroles with Sarcosine and Paraformaldehyde: A New Facet of Corrole Chemistry

“…These contracted macrocycles, with three hydrogens in the inner core, present remarkable and unique properties, such as the ability to stabilize metal ions in high oxidation states, higher acidity, as well as higher emissions and quantum yields when compared to their porphyrinic counterparts [ 3 , 4 , 5 , 6 ]. These features are responsible for corroles’ unusual reactivity and, sometimes, unpredictable behavior, making the corrole macrocycles of great interest in various research areas, namely in the development of tumor-targeting and imaging drugs, antitumoral and antimicrobial photodynamic therapy [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ], sensing [ 25 , 26 , 27 , 28 , 29 , 30 ], design of light-harvesting systems [ 31 , 32 , 33 ], and catalysis [ 4 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ].…”