Sensitivity of Fungal Microbe Aspergillus niger to New Synthetic Analogs of Natural Isocoumarin Antibiotics

Abstract

The sensitivity of field cultures of fungal microbe Aspergillus niger to new synthetic analogs of natural antifungal antibiotics of the isocoumarin class was determined in comparison with antimycotic activity of known drugs. The minimal mycocidal concentration (MMCC) and minimal mycostatic concentration (MMSC) of the drugs were documented. The inhibitory effect (IE) was expressed as the ratio of the average colony diameter of experimental samples to the average colony diameter of control samples. From the results presented in the present work, it follows that the investigated field cultures of Aspergillus niger are most sensitive to antimycotic drugs belonging to N-methylnaphthylmethylamine derivatives and polyene antimycotics — terbinafine (MMSC = 0–2 µg/cm3) and nystatin (MMSC = 4–8 µg/cm3, IE-1 = 1.69, IE-K2 = 1.51), which have a pronounced mycocidal effect. Other studied preparations, including synthesized analogues of natural isocoumarins, showed only mycostatic effect on cultures of fungal microbe Aspergillus niger: fluconazole — MMSC = more than 64 µg/cm3, IE-K1 = 3.38, IE-K2 = 2.52; griseofulvin — MMSC = more than 64 µg/cm3, IE-K1 = 1.79, IE-K2 = 1.53; 3-(3-oxobutyl)-isocoumarin — MMSC = more than 64 µg/cm3, IE-K1 = 1.27, IE-K2 = 1.07; 7-fluoro-3-(oxobutyl)-1-N-isochromene-1-one — MMSC = greater than 64 µg/cm3, IE-K1 = 1.28, IE-K2 = 1.03; (E)-3-(3-oxobutyl-1-en-1-yl)-1-N-isochromene-1-one — MMSC = greater than 64 µg/cm3, IE-K1 = 1.12, IE-K2 = 1.06; 3-(3,3-difluorobutyl)-1-N-iso-chromene-1-one — MMSC = greater than 64 µg/cm3, IE-K1 = 1.34, IE-K2 = 1.25.