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Photodynamic fungicidal efficacy of hypericin and dimethyl methylene blue against azole‐resistant Candida albicans strains
Author(s) -
PazCristobal M. P.,
Royo D.,
Rezusta A.,
AndrésCiriano E.,
Alejandre M. C.,
Meis J. F.,
Revillo M. J.,
Aspiroz C.,
ll S.,
Gilaberte Y.
Publication year - 2014
Publication title -
mycoses
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 69
eISSN - 1439-0507
pISSN - 0933-7407
DOI - 10.1111/myc.12099
Subject(s) - candida albicans , phototoxicity , azole , microbiology and biotechnology , chemistry , methylene blue , corpus albicans , fungicide , photodynamic therapy , hypericin , biology , pharmacology , antifungal , in vitro , biochemistry , organic chemistry , botany , photocatalysis , catalysis
Summary Antimicrobial photodynamic therapy ( aPDT ) is an emerging alternative to treat infections based on the use of photosensitisers ( PSs ) and visible light. To investigate the fungicidal effect of PDT against azole‐resistant Candida albicans strains using two PS s with a different mechanism of action, hypericin ( HYP ) and 1,9‐dimethyl methylene blue ( DMMB ), comparing their efficacy and the reactive oxygen species ( ROS ) species involved in their cytotoxicity. Azole‐resistant and the azole‐susceptible C. albicans strains were used. Solutions of 0.5 and 4 McFarland inoculum of each C andida strain were treated with different concentrations of each PS, and exposed to two light‐emitting diode light fluences (18 and 37 J cm −2 ). Mechanistic insight was gained using several ROS quenchers. The minimal fungicidal concentration of HYP for ≥3 log 10 CFU reduction (0.5 McFarland) was 0.62 μmol l −1 for most strains, whereas for DMMB it ranged between 1.25 and 2.5 μmol l −1 . Increasing the fluence to 37 J cm −2 allowed to reduce the DMMB concentration. Higher concentrations of both PS s were required to reach a 6 log 10 reduction (4 McFarland). H 2 O 2 was the main phototoxic species involved in the fungicidal effect of HYP ‐a PDT whereas 1 O 2 was more important for DMMB ‐based treatments. a PDT with either HYP or DMMB is effective in killing of C . albicans strains independent of their azole resistance pattern. HYP was more efficient at low fungal concentration and DMMB at higher concentrations.