Efeito da veiculação de compostos fenotiazínicos na inativação de candida albicans por terapia fotodinâmica

Abstract

Oral candidiasis is a pathology frequently diagnosed in immunocompromised patients and its treatment is done with the prescription of antifungals. However, treatment does not always result in the cure of the disease, due to resistance to treatment. Thus, photodynamic antimicrobial therapy (PACT) is an antimicrobial alternative, especially with regard to resistant strains. However, the physical-chemical properties of photosensitizers (PSs) can make PACT treatment unfeasible. Recently, our research group showed that the aggregation control enhances the PACT action of methylene blue. The aim of this study was to investigate PACT under the influence of different means in order to modulate the aggregation of phenothiazine FSs Azure A (AA), Azure B (AB) and 1,9-dimethylmethylene blue (DMAM). Plankton cells of C. albicans (ATCC 10231) were treated with PS in different concentrations (0–100 mg / L), in the dark and irradiated (LED of 640 ± 12 nm for 30 min, 2.6 mW/cm2). After treatments, diluted samples were grown on Sabouraud Dextrose Agar and maintained at 37°C for 24 h. After defining a single concentration of each PS, the inoculum was treated with the PS in different media (water, phosphate buffered saline - PBS, physiological solution - 0.9% NaCl, 1 mol/L urea and sodium dodecyl sulfate 0, 25% - SDS), 20 mg/L for AA and AB, and 0.5 mg/L for DMMB. Cellular incorporation and the dimer/monomer ratio were determined. Our results showed that PACT with these PSs reduced the number of CFU/mL, with DMMB being the most effective due to the greater cellular incorporation within the series. When PACT was applied in different media, the inactivation response was influenced by the medium, with SDS being the only medium that potentiated the action of PACT and the inactivation of the microorganism was achieved with AB and DMMB. Therefore, DMMB presented the greatest PACT action within the studied PS, reaching inactivation of the microorganism with a concentration of 1 mg/L, mainly due to its high cellular incorporation. The 0.25% SDS increased the PACT action of the studied PSs, mainly with DMMB and AB. This result can be used in formulations to develop effective treatments in future clinical studies.