Phthalocyanine Thio‐Pyridinium Derivatives as Antibacterial Photosensitizers^†

Abstract

This study describes the synthesis of three new tetra‐ and octa‐thio‐pyridinium phthalocyanine derivatives. PSs 3a and 4a were prepared from the tetramerization of phthalonitriles 1 and 2, respectively, whereas PS 5 was prepared from the nucleophilic substitution of the 8 beta fluor atoms of hexadecafluorophthalocyaninatozinc(II) by mercaptopyridine, followed by cationization. The recombinant bioluminescent Escherichia coli strain was used to assess, in real time, the photoinactivation efficiency of these cationic phthalocyanines, under white and red light. The cellular localization and uptake were also determined to assess the potential of the new phthalocyanines as antibacterial agents. Derivative 3a was the most effective PS, causing a 5 logs reduction in bioluminescence after 30 min of irradiation under white or red lights. The photoinactivation efficiency of the phthalocyanine 4a was similar (5 logs reduction in bioluminescence) to that of 3a when irradiated with white light, but the efficiency of inactivation was reduced (2.1 logs reduction in bioluminescence) under red light. The tetra‐substituted phthalocyanine 3a also generates high amounts of singlet oxygen, does not aggregate in PBS and is highly fluorescent, which makes it an effective PS and a promising fluorescent labeling.

Fluorinated porphyrinoids as efficient platforms for new photonic materials, sensors, and therapeutics

“…The product was obtained in quantitative yields. 115 Antiviral PDT activity was studied on this compound but did not show promising results.…”

Antimicrobial Photodynamic Therapy with Decacationic Monoadducts and Bisadducts of [70]Fullerene: In Vitro and In Vivo Studies

“…Thirdly, mammalian cells take up polycationic molecules by the relatively slow process of adsorptive endocytosis, so if light is delivered soon after application of the cationic PS to the infected tissue, the desired selectivity for bacteria in tissue can be achieved [13]. A pronounced increase in the number of charges on the PS molecule may not always increase the efficiency of the PS in antimicrobial PDT [14,15] if these charges serve solely for the purpose of targeting bacteria. However, we have recently demonstrated the use of these multiple cationic charges to carry the same number of iodide atoms as counter anions to improve type I photochemistry by allowing a photoinduced electron-transfer mechanism from the iodide to the fullerene cage [16].…”

In vitro antimicrobial activity of light-activated phthalocyanines

“…Therefore, at present, members of these families of compounds may represent the photosensitizers of choice for clinical PDT of microbial infections. Phthalocyanines seem to be a promising group in that respect [13]. Phthalocyanines are effective photosensitive substances.…”