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

Abstract

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.

Photophysical and Antibacterial Properties of Porphyrins Encapsulated inside Acetylated Lignin Nanoparticles

“…While most of the free porphyrins and nanoparticles were able to diminish the bacterial count of S. aureus , only the free cationic porphyrins were able to kill E. coli , as thoroughly explored in the literature [ 38 , 46 , 47 ]. Interestingly, T(MAP)PP@AcLi was unable to diminish the bacterial counts of E. coli .…”

Photodynamic Therapy—An Up-to-Date Review

“…The main types of light sources employed in PDT are lasers, light-emitting diodes, and lamps, the choice depending on the target location, absorption spectrum of the used photosensitizer, and required light dose [20]. Under appropriate light irradiation, the non-toxic photosensitizing compound placed at the target site is activated, being able to absorb and transfer electrons, while the in situ found oxygen molecules act as electron acceptors [19,21,22]. Hence, cytotoxic reactive oxygen species (ROS) are generated, producing irreversible damage to microorganisms and target tissues by rupturing the cell membrane and causing cell death by necrosis or apoptosis [17,19,[23][24][25].…”

“…There are two main types of ROS, each corresponding to a distinctive PDT mechanism (Figure 2). By electron transfer are produced oxygen radicals (e.g., superoxide anion O2 •− , hydroxyl radical HO • , hydroperoxyl radical HOO • ), while by energy transfer is obtained singlet oxygen ( 1 O2) [21]. Type I mechanism supposes the transition of PS molecules from the ground state to the singlet excited state and to the triplet excited state [8].…”

“…•− , hydroxyl radical HO • , hydroperoxyl radical HOO • ), while by energy transfer is obtained singlet oxygen ( 1 O 2 ) [21]. Type I mechanism supposes the transition of PS molecules from the ground state to the singlet excited state and to the triplet excited state [8].…”

Curcumin-mediated photodynamic antimicrobial chemotherapy (PACT): a systematic review / Quimioterapia fotodinâmica antimicrobiana (PACT) mediada por curcumina: uma revisão sistemática

“…Under appropriate light irradiation, there is production of singlet oxygen by energy transfer, as well as production of reactive oxygen compounds, formed by electron transfer. These reactive oxygen compounds react rapidly with a wide spectrum of molecules, including those found in the bacterial wall and membrane components, leading to cell damage which ultimately leads to cell death (Le Guern et al, 2021). Additionally, the germicidal action of PACT depends on a combination of four factors: the type of photosensitizer, the light energy source, the wavelength and exogenous oxygen (Araújo et al, 2017).…”