Photophysical and Bactericidal Properties of Pyridinium and Imidazolium Porphyrins for Photodynamic Antimicrobial Chemotherapy

Despite advances achieved over the last decade, infections caused by multi-drug-resistant bacterial strains are increasingly becoming important societal issues that need to be addressed. New approaches have already been developed in order to overcome this problem. Photodynamic antimicrobial chemotherapy (PACT) could provide an alternative to fight infectious bacteria. Many studies have highlighted the value of cationic photosensitizers in order to improve this approach. This study reports the synthesis and the characterization of cationic porphyrins derived from methylimidazolium and phenylimidazolium porphyrins, along with a comparison of their photophysical properties with the well-known N-methylpyridyl (pyridinium) porphyrin family. PACT tests conducted with the tetracationic porphyrins of these three families showed that these new photosensitizers may offer a good alternative to the classical pyridinium porphyrins, especially against S.aureus and E.coli. In addition, they pave the way to new cationic photosensitizers by the means of derivatization through amide bond formation

Synthesis, Photophysical Characterization and Evaluation of Biological Properties of C7, a Novel Symmetric <i>Tetra</i>-Imidazolium-<i>Bis</i>-Heterocycle

A novel symmetric tetra-imidazolium-bis-heterocycle, called C7, was designed and synthesized in a quick two-step pathway, with the objective to synthesize biologically active supramolecular assembly. The synthesized compound was then analyzed for its photophysical properties, for a potential application in theragnostic (fluorescence) or phototherapy (photodynamic therapy, with the production of reactive oxygen species, such as singlet oxygen 1O2). C7 was thus screened for its biological activity, in particular against important human pathogens of viral origin (respiratory viruses such as adenovirus type 2 and human coronavirus 229E) and of fungal and bacterial origin. The compound showed limited antiviral activity, combined with very good antiproliferative activity against breast cancer, and head and neck squamous cell carcinoma models. Interestingly, the selected compound showed excellent antibacterial activity against a large array of Gram-positive and Gram-negative clinically isolated pathogenic bacteria, with a possible inhibitory mechanism on the bacterial cell wall synthesis studied with electron microscopy and molecular docking tools. Collectively, the newly synthesized compound C7 could be considered as a potential lead for the development of new antibacterial treatment, endowed with basic photophysical properties, opening the door towards the future development of phototherapy approaches

Multistate Photo-Induced Relaxation and Photoisomerization Ability of Fumaramide Threads: A Computational and Experimental Study

International audienceFumaric and maleic amides are the photoactive..