Resomycins A to approximately C: new anthracyclinone antibiotics formed by a terrestrial Streptomyces sp.

During the screening of Actinomycetes for novel bio-active components, we found that the terrestrial Streptomyces sp. isolate GW71/2497 produced large quantities of chartreusin, which precipitated during the concentration of the extract and was responsible for the high activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Streptomyces viridochromogenes (Tü 57). On a soybean flour/mannitol medium instead of malt extract/yeast extract/glucose, the strain produced a totally different metabolic pattern: In addition to the metabolites detected previously, the TLC showed nonpolar yellow and orange zones giving a yellow or orange fluorescence under UV at 366 nm and colour reactions with sodium hydroxide characteristic for perihydroxyquinones. The work-up of the extract resulted in the isolation of several known compounds and of three new anthracyclinone antibiotics 2 ~ 4 which we named resomycin A ~ C. In this paper we report the taxonomy of the producing strain, the structure elucidation of 1a ~ 4 and on the biological activity of these compounds.