Antifungal effect of photodynamic therapy mediated by curcumin on Candida albicans biofilms in vitro.

BACKGROUND

Canida albicans can cause opportunistic infections ranging from superficial mucous membrane lesions to life-threatening disease. The aim of this study is to investigate the antifungal effect of photodynamic therapy (PDT) mediated by curcumin (CUR) on C. albicans biofilms in vitro.

METHODS

One standard strain ATCC 90028 and two clinical isolates from HIV (CCA1) and oral lichen planus (CCA2) patients' oral cavities were used in this study. Biofilms were photosensitized with 60 μM CUR and irradiated by light emitting diode (LED) under the wavelength of 455 nm and energy densities of 2.64, 5.28, 7.92, 10.56, 13.2 J/cm2. Then the antifungal effects of CUR-PDT were evaluated by XTT reduction assay and confocal light scanning microscopy (CLSM) observations. The effects of CUR-PDT on the expression levels of hypha-specific and biofilm-related genes including EFG1, UME6, HGC1 and ECE1 were assessed by quantitative Real-time PCR (qRT-PCR) method.

RESULTS

The inhibition rates after CUR-PDT in three biofilms(ATCC 90028, CCA1, CCA2)were 90.87%, 66.44% and 86.74% respectively (p < 0.05). Relative gene expression levels of EFG1, UME6, HGC1 and ECE1 were all downregulated after CUR-PDT, with fold-decrease of 6.865, 3.382, 2.167 and 6.887 in ATCC 90028, 2.466, 2.146, 1.627 and 3.102 in CCA1, and 5.406, 2.347, 2.073and 3.711 in CCA2 (p < 0.05).

CONCLUSIONS

Curcumin-mediated PDT could effectively inactivateCandida albicans biofilms in vitro. Expression of genes involved in biofilms formation were downregulated after CUR-PDT.