Source Year: 2000

Latex from H. brasiliensis and its subcellular fractions (L-serum and C-serum) were tested for antifungal activity alone or in combination with fluconazole. C.albicans growth was inhibited with the same efficacy when yeasts were inoculated into culture medium supplemented over the total growth phase with latex as when latex was added during the exponential phase only; the minimum inhibitory concentration (MIC 80;) of H. brasiliensis latex was 123 micro g/ml. By means of a non-linear regression analysis of the experimental data, 2 distinct fixation sites for fluconazole (FCZ) were determined: one of strong affinity (Kaff=0.0162 micro g/ml) and another of low aminity (Kaff=0.0071 micro g/ml). After addition of a mixture of FCZ and latex during the exponential phase, the affinity constant of yeasts for FCZ was calculated; when latex was in a final concentration of 21 micro g/ml (Kaff= 1 micro g/ml) or 42 micro g/ml (Kaff=0.277 micro g/ml) and without latex (Kaff=0.0502 micro g/ml). In 2 cases a synergistic effect between latex and FCZ was obtained. The highest efficacy was obtained with a latex concentration of 21 micro g/ml. The addition of subcellular fractions of latex, L-serum and C-serum, did not cause an antifungal effect. Electron microscopy observations indicated a limited cell wall degradation and a high percentage of coagulated yeasts.