Antifungal activity against Aspergillus fumigatus mycelial cells measured by wet weight, protein concentration and enzymatic activity

The activity of amphotericin B, miconazole, fluconazole and itraconazole against mycelial cells of Aspergillus fumigatus was examined by changes in wet weight, protein concentration and enzymatic activity. The wet weight of mycelial cells decreased with increasing concentrations of the studied antifungal agents proportionally to the minimale inhibitory concentrations (MICs). Itraconazole showed the most potent activity against A. fumigatus followed by miconazole, amphotericin B, and fluconazole. The concentration of soluble protein in disrupted mycelial cells increased at drug concentrations lower than the MICs and showed a marked decrease at concentrations higher than the MICs. Percent protein at high concentrations was 8 p. 100 at 0.015 μg/ml of itraconazole, 5 p. 10 at 0.2 μg/ml of amphotericin B, 5 p. 100 at 0.5 μg/ml of miconazole and 88 p. 100 at 100 μg/ml of fluconazole. The activity of metabolic enzymes glucose-6-phosphate dehydrogenase (G6PD), fumarase (Fmase) and glutamate dehydrogenase (GDH) of A. fumigatus treated with antifungal agents was measured by polyacrylamide gel electrophoresis. The enzymatic activity of G6PD and GDH remarkably decreased in proportion to the increase in concentration of itraconazole. However, the enzymatic activity was no change in proportion to the increase in concentration of fluconazole. The enzymatic activity of Fmase and G6PD decreased in proportion to the increase in concentration of miconazole. The enzyme activity of GDH was not changed, but the activity of G6PD and Fmase decreased in proportion to the increase in concentration of amphotericin B. Antifungal activity as measured by the protein concentration and metabolic enzyme activity of A. fumigatus mycelial cells indicated the fungistatic action of the studied antifungal agents.