Spectomycins, new antibacterial compounds produced by Streptomyces spectabilis: isolation, structures, and biosynthesis

Three new tetrahydroanthracene antibiotics have been isolated from modified culture broths of Streptomyces spectabilis. The new compounds, spectomycins A1, A2 and B1, exist as monomeric (C20H20O7, A1; C19H18O7, A2) and as symmetrical dimeric (C38H34O14; B1) forms. Only spectomycin B1 has moderate activity against Gram-positive microorganisms. We report here the structure elucidation and biosynthetic origin of these compounds.