The role of oxidative and nitrosative bursts caused by azoles and amphotericin B against the fungal pathogen Cryptococcus gattii

• Published in: Journal of antimicrobial chemotherapy 2013-08, Vol.68 (8), p.1801-1811
• Main Authors: Ferreira, Gabriella Freitas, Baltazar, Ludmila de Matos, Santos, Julliana Ribeiro Alves, Monteiro, Andrea Souza, Fraga, Lucia Alves de Oliveira, Resende-Stoianoff, Maria Aparecida, Santos, Daniel Assis
• Format: Article
• Language: English
• Subjects: Amphotericin B - pharmacology; Antifungal Agents - pharmacology; Antioxidants; Cells; Cryptococcus; Cryptococcus gattii - drug effects; Cryptococcus gattii - metabolism; Enzymes; Fungi; Itraconazole - pharmacology; Nitrosation; Oxidative stress; Oxygen; Peroxynitrous Acid - metabolism; Peroxynitrous Acid - toxicity; Reactive Oxygen Species - metabolism; Reactive Oxygen Species - toxicity; Respiratory Burst
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkt114

Although the most accepted mechanisms of action of amphotericin B and azoles are related to ergosterol, it is possible that these drugs have other effects on the fungal cell. In the present study, the role of endogenous reactive oxygen species (ROS) and peroxynitrite produced by azoles and amphotericin B in the fungus Cryptococcus gattii were examined. We studied distinct parameters to evaluate the effect of oxidative and nitrosative stresses induced by these drugs in C. gattii cells: lipid peroxidation, ergosterol content, ROS and peroxynitrite production, enzymatic activity of the antioxidant system and the in vitro interaction of antifungal drugs with a peroxidase inhibitor, a superoxide dismutase inhibitor and a peroxynitrite scavenger. The data demonstrated that itraconazole led to ROS formation and lipid peroxidation in C. gattii cells in the early stages of the treatment; this did not occur with fluconazole. This phenomenon strongly increased the activities of enzymes of the antioxidant system. These results were confirmed by synergism observed between the catalase inhibitor and itraconazole. Amphotericin B caused lipid peroxidation in C. gattii cells through a greatly enhanced production of oxidative and nitrosative radicals with increased peroxidase activity. These data were confirmed by the synergism between the catalase/superoxide dismutase inhibitors and amphotericin B. In addition, the effect of this antifungal was antagonized by the peroxynitrite scavenger. Oxidative and nitrosative bursts play an important role in the antifungal activity of itraconazole and amphotericin B against C. gattii.