UK-3A, a novel antifungal antibiotic from Streptomyces sp. 517-02: fermentation, isolation, structural elucidation and biological properties.

A novel antifungal antibiotic, UK-3A, was obtained from the mycelial cake of Streptomyces sp. 517-02. UK-3A was very similar in structure to UK-2A, a structural relative of antimycin A. The antifungal spectrum of UK-3A was relatively broad (MICs for yeasts and filamentous fungi: 1.56-6.25 and 0.39-1.56 micrograms/ml, respectively). The cytotoxic activity of UK-3A was weak (IC50: 18-100 micrograms/ml).