Genotoxic effect of photodynamic therapy mediated by curcumin on Candida albicans

Abstract

Photodynamic therapy (PDT) is a promising method for localized and speci c inactivation of fungi and bacteria. A nontoxic light-sensitive compound is taken up by cells, which are then exposed selectively to light, which activates toxicity of the compound. We investigated the potential of sublethal PDT using light-sensitive curcumin (CUR) in combination with blue (455 nm) light to promote reactive oxygen species (ROS) formation in the form of singlet oxygen and DNA damage of Candida albicans. Surprisingly, CUR-mediated PDT but also light alone caused signi cantly longer comet tails, an indication of DNA damage of C. albicans when compared with the negative control. The intracellular ROS production was also signi cantly higher for the group treated only with light. However, PDT compared to blue light alone signi cantly slowed DNA repair. Comet tails decreased during 30 min visualized as a 90% reduction in length in the absence of light for cells treated with light alone, while comet tails of cells treated with PDT only diminished in size about 45%. These results indicate that complex mechanisms may result in PDT in a way that should be considered when choosing the photosensitive compound and other aspects of the treatment design.