PERALTA MARIANA ANDREA
Congresos y reuniones científicas
Título:
COMPARISON OF ANTIFUNGAL ACTIVITY OF NATURAL PRENYLATED FLAVANONES AGAINST Candida albicans BIOFILMS
Autor/es:
PERALTA MARIANA A; DA SILVA, MARIA ANGEL; ORTEGA, M. GABRIELA; CABRERA JOSE L.; PARAJE, MARÍA GABRIELA
Lugar:
Córdoba
Reunión:
Congreso; XI CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE; 2015
Institución organizadora:
Sociedad Arentina de Microbiología General (SAMIGE)
Resumen:
Introduction:
The formation of biofilms is an important virulence factor that allows C. albicans to cause many types of infections and is responsible for most cases of candidiasis at both mucosal and systemic sites. It has been reported that Candida biofilms are 30-2000 times more resistant to several antifungal agents compared to their planktonic (or free-living) counterparts. The continuing emergence of infections with antifungal resistant Candida strains requires a constant search for new antifungal drugs, with the plant kingdom being an important source of chemical structures.
Objective:
The present study compared a the antifungal effect of a new prenylated flavanones of Dalea boliviana Britton (2S)-5,7,2´-trihydroxy-5´-(1´´´,1´´´-dimethylallyl)-8-prenylflavanone (1) and
(2S)-5,7,2´-trihydroxy-8,3´-diprenylflavanone (2) and a natural prenylflavonoid D. elegans
(2?,4?-dihydroxy-5?-(1???, 1???-dimethylallyl)-8-prenylpinocembrin-8PP), on Candida albicans biofilms, and compared this with an azole antifungal (fluconazole).
Material and Methods:
The fluconazole sensitive (SCa) and azole-resistant (RCa) C. albicans strains were used, with biofilm formation being studied using crystal violet (CV) and confocal scanning laser microscopy (CSLM). The minimal inhibitory concentration for sessile cells (SMIC) was defined as the concentration of antifungal that caused a 50% (SMIC 50) and 80% (SMIC 80) reduction of treated biofilms. Biofilms were grown on disks and examined by CSLM using Calcofluor-White, a UV-excitable dye that binds chitin and beta-glucan, which has long been used to highlight fungal cell walls.
Results: The results from our study showing that 8PP has similar pronounced antibiofilm effects against sensible and resistant C. albicans strains. While the flavonoid (8PP) concentration is higher than the antifungal of a comparative reference (fluconazole), the biofilm formation was strongly inhibited (>85%) by 8PP at 100 mM.It was observed that the cellular viability of biofilms decreased with increased concentration of the compounds assayed, with the results showing a correlation between the CV assay and CFU/ml. The hazy biofilm appearance was due to diffuse staining of the extracellular material with Calcofluor-White, and implies that this material was composed of mainly cell-wall-like polysaccharides. In the antifungal-treated C. albicans biofilm, the majority of C. albicans cells were present as blastospores (yeast forms) attached to the surface of the disk, which appeared as a haze-like film covering the fungal microcolonies. Biofilms treated with 8PP, the thickness was reduced significantly, with cells being fewer and of less density compared to those of the untreated control (p < 0.001). Similar images were obtained with fluconazole.
Conclusion: Our data suggest that 8PP may be useful for the treatment of biofilm-related Candida infections, 8PP may also have a therapeutic potential in C. albicans infections. Further studies are still necessary in order to increase the understanding of the mechanisms of antibiofilm activity of this compound.
The formation of biofilms is an important virulence factor that allows C. albicans to cause many types of infections and is responsible for most cases of candidiasis at both mucosal and systemic sites. It has been reported that Candida biofilms are 30-2000 times more resistant to several antifungal agents compared to their planktonic (or free-living) counterparts. The continuing emergence of infections with antifungal resistant Candida strains requires a constant search for new antifungal drugs, with the plant kingdom being an important source of chemical structures.
Objective:
The present study compared a the antifungal effect of a new prenylated flavanones of Dalea boliviana Britton (2S)-5,7,2´-trihydroxy-5´-(1´´´,1´´´-dimethylallyl)-8-prenylflavanone (1) and
(2S)-5,7,2´-trihydroxy-8,3´-diprenylflavanone (2) and a natural prenylflavonoid D. elegans
(2?,4?-dihydroxy-5?-(1???, 1???-dimethylallyl)-8-prenylpinocembrin-8PP), on Candida albicans biofilms, and compared this with an azole antifungal (fluconazole).
Material and Methods:
The fluconazole sensitive (SCa) and azole-resistant (RCa) C. albicans strains were used, with biofilm formation being studied using crystal violet (CV) and confocal scanning laser microscopy (CSLM). The minimal inhibitory concentration for sessile cells (SMIC) was defined as the concentration of antifungal that caused a 50% (SMIC 50) and 80% (SMIC 80) reduction of treated biofilms. Biofilms were grown on disks and examined by CSLM using Calcofluor-White, a UV-excitable dye that binds chitin and beta-glucan, which has long been used to highlight fungal cell walls.
Results: The results from our study showing that 8PP has similar pronounced antibiofilm effects against sensible and resistant C. albicans strains. While the flavonoid (8PP) concentration is higher than the antifungal of a comparative reference (fluconazole), the biofilm formation was strongly inhibited (>85%) by 8PP at 100 mM.It was observed that the cellular viability of biofilms decreased with increased concentration of the compounds assayed, with the results showing a correlation between the CV assay and CFU/ml. The hazy biofilm appearance was due to diffuse staining of the extracellular material with Calcofluor-White, and implies that this material was composed of mainly cell-wall-like polysaccharides. In the antifungal-treated C. albicans biofilm, the majority of C. albicans cells were present as blastospores (yeast forms) attached to the surface of the disk, which appeared as a haze-like film covering the fungal microcolonies. Biofilms treated with 8PP, the thickness was reduced significantly, with cells being fewer and of less density compared to those of the untreated control (p < 0.001). Similar images were obtained with fluconazole.
Conclusion: Our data suggest that 8PP may be useful for the treatment of biofilm-related Candida infections, 8PP may also have a therapeutic potential in C. albicans infections. Further studies are still necessary in order to increase the understanding of the mechanisms of antibiofilm activity of this compound.
