Phenelfamycins, a novel complex of elfamycin-type antibiotics. II. Isolation and structure determination

A novel complex of elfamycin-type antibiotics has been isolated from submerged fermentation of either Streptomyces violaceoniger AB 999F-80 or Streptomyces violaceoniger AB 1047T-33. Antibiotics were extracted from the fermentation broth with ethyl acetate and from the mycelia with acetone. Purification of individual components was achieved by a combination of solvent partitions, Sephadex LH-20 exclusion, C18 bonded-phase silica gel adsorption, diol partition and liquid-liquid countercurrent chromatographies. Seven closely related components were separated and assigned structures 4, 11, 12, 13, 14, and 16 to phenelfamycins A to F respectively and structure 17 to unphenelfamycin. These structures were elucidated employing a variety of spectroscopic techniques, including extensive use of 1D and 2D NMR spectroscopy.