Carboranyl-Chlorin e6 as a Potent Antimicrobial Photosensitizer

Abstract

Antimicrobial photodynamic inactivation is currently being widely considered as alternative to antibiotic chemotherapy of infective diseases, attracting much attention to design of novel effective photosensitizers. Carboranyl-chlorin-e6 (the conjugate of chlorin e6 with carborane), applied here for the first time for antimicrobial photodynamic inactivation, appeared to be much stronger than chlorin e6 against Gram-positive bacteria, such as Bacillus subtilis, Staphyllococcus aureus and Mycobacterium sp. Confocal fluorescence spectroscopy and membrane leakage experiments indicated that bacteria cell death upon photodynamic treatment with carboranyl-chlorin-e6 is caused by loss of cell membrane integrity. The enhanced photobactericidal activity was attributed to the increased accumulation of the conjugate by bacterial cells, as evaluated both by centrifugation and fluorescence correlation spectroscopy. Gram-negative bacteria were rather resistant to antimicrobial photodynamic inactivation mediated by carboranyl-chlorin-e6. Unlike chlorin e6, the conjugate showed higher (compared to the wild-type strain) dark toxicity with Escherichia coli ΔtolC mutant, deficient in TolC-requiring multidrug efflux transporters.

Antimicrobial Photodynamic Inactivation Mediated by Rose Bengal and Erythrosine Is Effective in the Control of Food-Related Bacteria in Planktonic and Biofilm States

“…In this study, K + leakage was observed for all bacteria tested when PS was combined with irradiation. The results obtained corroborate the cell surface changes observed from contact angles measurements and are in agreement with another studies [ 39 ] where K + leakage was observed after aPDI. Xanthene dyes are amphiphilic molecules and according to the partition coefficients they present lipophilic tendency [ 40 ].…”

Cobalt Bis-Dicarbollide Enhances Antibiotics Action towards Staphylococcus epidermidis Planktonic Growth Due to Cell Envelopes Disruption

“…Further studies brought positive information about the antimicrobial activity of various bis- o -dicarbaboranes, closo - o -dicarbaboranes, and nido -type dicarbollide anions towards the representatives of microscopic fungi and bacteria Staphylococcus aureus , Streptococcus pyogenes , Escherichia coli , Klebsiella pneumoniae , Mycobacterium spp., Enterobacter cloacae , Pseudomonas aeruginosa , Acinetobacter baumannii , etc. [ 36 , 37 , 38 , 39 , 40 , 41 ]. More information about these properties was published in an article focused on the antimicrobial activity of COSAN derivatives [ 32 ].…”

Alternatives to Antibiotics: Phage Lytic Enzymes and Phage Therapy

“…Antimicrobial photodynamic therapy or inactivation (aPDT or aPDI) is new effective method of killing gram-negative and gram-positive bacteria and yeast [33][34][35][36]. aPDI employs a non-thermal reaction induced by the interactions between visible light photons and a photosensitizer, such as methylene blue, chlorin, porphyrin, chlorophyll or their derivatives, in the presence of oxygen.…”