AMIDOMYCIN, A NEW ANTIBIOTIC FROM A STREPTOMYCES SPECIES. PRODUCTION, ISOLATION, ASSAY, AND BIOLOGICAL PROPERTIES

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Abstract
Antifungal preparations were obtained from cultures of Streplomyces PRL 1642 by solvent extraction of the solids collected after the pH was adjusted to 3.5. The active factor, named amidomycin, was purified by repeated crystallization from aqueous ethanol or petrol (b.p. 60°–80 °C.) to give stable, colorless, optically active needles, m.p. 192 °C.Amidomycin suspended in agar media retarded the growth of many filamentous fungi and noticeably inhibited the plant pathogens Ustilago maydis, Ustilago trebouxii, as well as the human pathogen, Hormodendrum pedrosoi. It also inhibited the germination of uredospores of Puccinia graminis at low concentrations. Certain yeasts were completely inhibited by small concentrations of amidomycin; the quantity required was affected by the number of cells in the inoculum.None of the bacteria examined was inhibited by this antibiotic. At certain concentrations it was lethal to Candida albicans as determined by the inability of previously exposed and washed cells to grow on nutrient agar.Although a few isolated colonies of Candida albicans usually developed on plates containing approximately double the concentration required to inhibit growth of the inoculum streak, serial transfer of progeny from such colonies onto agar containing amidomycin did not produce cultures having progressively increasing resistance.Two degradation products of amidomycin, D(–)-valine and 3,6-diisopropyl-2,5-diketomorpholine, are inactive.
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