New aminocoumarin antibiotics from a cloQ-defective mutant of the clorobiocin producer Streptomyces roseochromogenes DS12.976

Three new antibiotics, vanillobiocin, isovanillobiocin and declovanillobiocin, were isolated from the culture broth of a cloQ-defective mutant of the clorobiocin producer Streptomyces roseochromogenes, which is blocked in the biosynthesis of the prenylated 4-hydroxybenzoic acid moiety of clorobiocin. Spectroscopic analysis showed that the isolated compounds were similar to clorobiocin, but contained vanillic acid as the acyl component instead of the prenylated 4-hydroxybenzoic acid present in clorobiocin. Isovanillobiocin differs from vanillobiocin by the position of the pyrrole unit attached to the sugar moiety of the antibiotic. Declovanillobiocin lacks the chlorine atom at the aminocoumarin ring. All three compounds had lower antibiotic activity against Bacillus subtilis than clorobiocin.