Novel triene-beta-lactone antibiotics, oxazolomycin derivative and its isomer, produced by Streptomyces sp. KSM-2690.

In the course of our screening for novel antibacterial antibiotics produced by microorganisms, a strain termed KSM-2690was found to produce a new complex of triene/3-lactone antibiotics in the culture filtrate. The active principle was recovered from the broth filtrate with ethyl acetate extraction and could be divided into six components, three major components KSM-2690 A (1), B (2) and C (3), and three minor components KSM-2690 D, E and F, on the basis of their respective order of elution under the reverse-phase HPLC. The characteristic UV and IR spectra of their components were similar to those of oxazolomycins1'2^ indicating that these new compoundsare members of the triene-/3-lactone group of antibiotics.