Photoinduced antibacterial activity of two dicationic 5,15-diarylporphyrins

Abstract

Antimicrobial photodynamic treatment combines the use of photosensitizers (PSs) and visible light to kill bacterial cells. Cationic porphyrins are PSs largely used against bacteria and, among them, those featuring one positive charge on each of the 5,10,15,20-tetraaryl substituent (tetracationic) are the most used. The aim of this study was to synthesize two dicationic 5,15-di(N-alkyl-4-pyridyl)porphyrins, bearing methyl (PS 3) and benzyl (PS 4) N-alkylating groups, and to compare the efficiency in antibacterial photodynamic treatment, upon irradiation with a halogen-tungsten white lamp. The killing efficiency of the PS 4 was constantly found higher than that of the PS 3 against both pure and mixed cultures of laboratory model microorganisms as well as against wild wastewater microflora. The two PSs are comparable as regards singlet oxygen generation, but show a different repartition coefficient; the more lipophilic benzylated PS 4 shows a better interaction with the bacterial cells than the methylated one (PS 3). The data support the hypothesis that an efficient PS-cell binding is required to obtain significant effects. A correlation among cell binding, photoinactivation and PS lipophilicity is suggested.

Photodynamic Therapy by Diaryl-Porphyrins to Control the Growth of Candida albicans

“…Thus, porphyrins, widely investigated to photoinactivate bacteria, represent a family of promising photo-antifungals [47]. Among porphyrins, novel diaryl-porphyrins were active against Bacillus subtilis, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa [35,38]. Porphyrins can be chemically modified to yield a wide array of PSs featuring different substituents In the four available meso positions of the tetrapyrrole ring, to enhance their phototherapeutic effects [48].…”

“…The chemical denomination and structure of diaryl-porphyrins used In this study are listed In Table 1 [35,38,39]. Four porphyrins were neutral (1)(2)(3)(4), four were monocationic (5)(6)(7)(8), and three were dicationic (9)(10)(11).…”

New aminoporphyrins bearing urea derivative substituents: synthesis, characterization, antibacterial and antifungal activity

“…It is important to find alternate treatments for microbial infections. Porphyrins and their metallo-derivatives are significant biomimetic compounds that are used in the studies in the areas of chemistry, biology and biotechnology (Banfi et al 2006;Orlandi et al 2012Orlandi et al , 2013Dosselli et al 2013;Katsunori et al 2013). In the recent years, porphyrins have been studied as flexible model compounds.…”

Photodynamic antimicrobial chemotherapy with the novel amino acid-porphyrin conjugate 4I: In vitro and in vivo studies

“…Our team has performed much work on the synthesis, characterization, and mechanism study of conjugate 4I [9, 22]. It is gratifying that 4I displays some advantages including high quantum yields of 1 O 2 production (Φ Δ = 0.95), good biocompatibility and water-solubility compared to other porphyrins bearing unnatural or natural cationic groups [9, 13, 23–25]. …”