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The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates

Photodynamic action has been used for diverse biomedical applications, such as treating a broad range of bacterial infections. Based on the combination of light, dioxygen, and photosensitizer (PS), the photodynamic inactivation (PDI) approach led to the formation of reactive oxygen species (ROS) and...

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Autores principales: Ribeiro, Cláudia P. S., Faustino, Maria A. F., Almeida, Adelaide, Lourenço, Leandro M. O.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9026372/
https://www.ncbi.nlm.nih.gov/pubmed/35456769
http://dx.doi.org/10.3390/microorganisms10040718
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author Ribeiro, Cláudia P. S.
Faustino, Maria A. F.
Almeida, Adelaide
Lourenço, Leandro M. O.
author_facet Ribeiro, Cláudia P. S.
Faustino, Maria A. F.
Almeida, Adelaide
Lourenço, Leandro M. O.
author_sort Ribeiro, Cláudia P. S.
collection PubMed
description Photodynamic action has been used for diverse biomedical applications, such as treating a broad range of bacterial infections. Based on the combination of light, dioxygen, and photosensitizer (PS), the photodynamic inactivation (PDI) approach led to the formation of reactive oxygen species (ROS) and represented a non-invasive, non-toxic, repeatable procedure for pathogen photoinactivation. To this end, different tetrapyrrolic macrocycles, such as porphyrin (Por) dyes, have been used as PSs for PDI against microorganisms, mainly bacteria. Still, there is significant room for improvement, especially new PS molecules. Herein, unsymmetrical new pyridinone (3–5) and thiopyridyl Pors (7) were prepared with α-, β-, or γ-cyclodextrin (CD) units, following their quaternization to perform the corresponding free-base Pors (3a–5a and 7a), and were compared with the already-known Pors 6a and 8a, both bearing thiopyridinium and CD units. These water-soluble porphyrins were evaluated as PSs, and their photophysical and photochemical properties and photodynamic effects on E. coli were assessed. The presence of one CD unit and three positive charges on the Por structure (3a–5a and 7a) enhanced their aqueous solubility. The photoactivity of the cationic Pors 3a–5a and 6a–8a ensured their potential against the Gram-negative bacterium E. coli. Within each series of methoxypyridinium vs thiopyridinium dyes, the best PDI efficiency was achieved for 5a with a bacterial viability reduction of 3.5 log(10) (50 mW cm(−2), 60 min of light irradiation) and for 8a with a total bacterial viability reduction (>8 log(10), 25 mW cm(−2), 30 min of light irradiation). Here, the presence of the methoxypyridinium units is less effective against E. coli when compared with the thiopyridinium moieties. This study allows for the conclusion that the peripheral charge position, quaternized substituent type/CD unit, and affinity to the outer bacterial structures play an important role in the photoinactivation efficiency of E. coli, evidencing that these features should be further addressed in the pursuit for optimised PS for the antimicrobial PDI of pathogenic microorganisms.
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spelling pubmed-90263722022-04-23 The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates Ribeiro, Cláudia P. S. Faustino, Maria A. F. Almeida, Adelaide Lourenço, Leandro M. O. Microorganisms Article Photodynamic action has been used for diverse biomedical applications, such as treating a broad range of bacterial infections. Based on the combination of light, dioxygen, and photosensitizer (PS), the photodynamic inactivation (PDI) approach led to the formation of reactive oxygen species (ROS) and represented a non-invasive, non-toxic, repeatable procedure for pathogen photoinactivation. To this end, different tetrapyrrolic macrocycles, such as porphyrin (Por) dyes, have been used as PSs for PDI against microorganisms, mainly bacteria. Still, there is significant room for improvement, especially new PS molecules. Herein, unsymmetrical new pyridinone (3–5) and thiopyridyl Pors (7) were prepared with α-, β-, or γ-cyclodextrin (CD) units, following their quaternization to perform the corresponding free-base Pors (3a–5a and 7a), and were compared with the already-known Pors 6a and 8a, both bearing thiopyridinium and CD units. These water-soluble porphyrins were evaluated as PSs, and their photophysical and photochemical properties and photodynamic effects on E. coli were assessed. The presence of one CD unit and three positive charges on the Por structure (3a–5a and 7a) enhanced their aqueous solubility. The photoactivity of the cationic Pors 3a–5a and 6a–8a ensured their potential against the Gram-negative bacterium E. coli. Within each series of methoxypyridinium vs thiopyridinium dyes, the best PDI efficiency was achieved for 5a with a bacterial viability reduction of 3.5 log(10) (50 mW cm(−2), 60 min of light irradiation) and for 8a with a total bacterial viability reduction (>8 log(10), 25 mW cm(−2), 30 min of light irradiation). Here, the presence of the methoxypyridinium units is less effective against E. coli when compared with the thiopyridinium moieties. This study allows for the conclusion that the peripheral charge position, quaternized substituent type/CD unit, and affinity to the outer bacterial structures play an important role in the photoinactivation efficiency of E. coli, evidencing that these features should be further addressed in the pursuit for optimised PS for the antimicrobial PDI of pathogenic microorganisms. MDPI 2022-03-26 /pmc/articles/PMC9026372/ /pubmed/35456769 http://dx.doi.org/10.3390/microorganisms10040718 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Ribeiro, Cláudia P. S.
Faustino, Maria A. F.
Almeida, Adelaide
Lourenço, Leandro M. O.
The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates
title The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates
title_full The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates
title_fullStr The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates
title_full_unstemmed The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates
title_short The Antimicrobial Photoinactivation Effect on Escherichia coli through the Action of Inverted Cationic Porphyrin–Cyclodextrin Conjugates
title_sort antimicrobial photoinactivation effect on escherichia coli through the action of inverted cationic porphyrin–cyclodextrin conjugates
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9026372/
https://www.ncbi.nlm.nih.gov/pubmed/35456769
http://dx.doi.org/10.3390/microorganisms10040718
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