Effect of glutathione on rose bengal photosensitized yeast damage

Photodynamic treatment of Candida albicans cells in the presence of the sensitizer rose bengal at low concentration (2.5 microM) did not influence cell survival (100% survival after 60 min illumination). Cell damage was observed when 0.16 mM glutathione was added together with the dye to the cell suspension. A 99% cell inactivation was achieved after 15 min illumination. No preincubation of the cells with the sensitizer was needed. The mechanism of the photodynamic damage exerted by the combined action of rose bengal and glutathione was investigated using specific quenchers. The results suggest an enhancement involving stimulation of the singlet oxygen generation. The short term yeast inactivation achieved by a low concentration of the dye and glutathione may find an application in the design of an efficient anticandidose treatment.