Photodynamic inactivation of Escherichia coli by novel meso-substituted porphyrins by 4-(3-N,N,N-trimethylammoniumpropoxy)phenyl and 4-(trifluoromethyl)phenyl groups

Abstract

The photodynamic effect of novel cationic porphyrins, with different pattern of meso-substitution by 4-(3-N,N,N-trimethylammoniumpropoxy)phenyl (A) and 4-(trifluoromethyl)phenyl (B) groups, have been studied in both solution bearing photooxidizable substrates and in vitro on a typical Gram-negative bacterium Escherichia coli. In these sensitizers, the cationic groups are separated from the macrocycle ring by a propoxy spacer. Thus, the charges have a high mobility and a minimal influence on photophysical properties of the porphyrin. These compounds produce singlet molecular oxygen, O2(1Delta(g)), with quantum yields of approximately 0.41-0.53 in N,N-dimethylformamide. In methanol, the l-tryptophan photodecomposition increases with the number of cationic charges in the sensitizer. In vitro investigations show that cationic porphyrins are rapidly bound to E. coli cells in approximately 5 min. A higher binding was found for A3B3+ porphyrin, which is tightly bound to cells still after three washing steps. Photosensitized inactivation of E. coli cellular suspensions follows the order: A3B3+ > A44+>> ABAB2+ > AB3+. Under these conditions, a negligible effect was found for 5,10,15,20-tetra(4-sulfonatophenyl)porphyrin (TPPS4(4-)) that characterizes an anionic sensitizer. Also, the results obtained for these new cationic porphyrins were compared with those of 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin (TTAP4+), which is a standard active sensitizer established to eradicate E. coli. The photodynamic activity of TTAP4+ is quite similar to that produced by A4(4+). Studies in an anoxic condition indicate that oxygen is necessary for the mechanism of action of photodynamic inactivation of bacteria. The higher photodynamic activity of A3B3+ was confirmed by growth delay experiments. Photodynamic inactivation capacities of these sensitizers were also evaluated in E. coli cells immobilized on agar surfaces. Under these conditions, A3B3+ porphyrin retains a high activity to inactivate localized bacterial cells. Therefore, tricationic porphyrin A3B3+ is an interesting sensitizer with potential applications in photodynamic inactivation of bacteria in liquid suspensions or on surfaces.

Porphyrin-based cationic amphiphilic photosensitisers as potential anticancer, antimicrobial and immunosuppressive agents

“…Hydrophilic moieties derive from charged or uncharged polar head groups, and additional hydrophobic moieties most often from hydrocarbon (alkyl) chains (Pisarek et al 2014). Cationic amphiphilic porphyrin-based PSs obtained completely by synthesis are mostly meso-substituted porphyrins with different symmetry patterns, free or in complex with metal (Caminos et al 2006;Lazzeri and Durantini 2003). There are somewhat fewer examples of different cationic amphiphilic phthalocyanines, mostly metalated with zinc(II) (Dummin et al 1997;Kussovski et al 2009), but also with other metals such as silicon (Allen et al 2001;Mantareva et al 2013), then synthetic chlorins (Costa et al 2012a), bacteriochlorins (Sharma et al 2013;Yakubovskaya et al 2014) and isobacteriochlorins (Mesquita et al 2014).…”

“…Apart the introduction of a long(er) alkyl chain, lipophilicity of a molecule can be increased with a trifluoromethyl group (Böhm et al 2004), and a series of cationic amphiphilic porphyrins with one or more CF 3 groups, s u c h a s 5 -( 4 -t r i f l u o r o p h e n y l ) -1 0 , 1 5 , 2 0 -t r i s ( 4 -trimethylammoniumphenyl) porphyrin (TFAP(3+)) (Fig. 3) have been prepared, mostly for PACT applications (Lazzeri and Durantini 2003;Caminos et al 2006).…”

A simple experiment to show photodynamic inactivation of bacteria on surfaces

“…The results shown below represent typical student data. The capacity of these porphyrins to bind to bacterial cells of E. coli was previously studied in PBS suspension [19]. Porphyrin binding to bacterial cells can be determined by fluorescence analysis.…”

Desenvolvimento de membranas de quitosana com fotossensibilizadores incorporados visando à desinfecção de água

“…A alta força de oxidação do oxigênio singlete pode ser utilizada para induzir danos nas biomoléculas, os quais conduzirão à perda da funcionalidade biológica levando à inativação da célula (FAUST et al, 1999). Assim, não existe resistência microbiana natural contra PDI, não importando se a cepa é resistente a uma ou mais classes de agentes antimicrobianos (CAMINOS; SPESIA; DURANTINI, 2006).…”

“…cristalinidade de aproximadamente 72% e γ, possui cadeias antiparalelas e paralelas e ainda não é muito conhecida (CAMPANA-FILHO et al, 2007). Como principal fonte fornecedora de quitina, os laboratórios utilizam os exoesqueletos de crustáceos e molúsculos (CAMPANA-FILHO et al, 2007;MOURA et al, 2006;TAN et al, 1996).…”