Carbazomycins C, D, E and F, minor components of the carbazomycin complex

Carbazomycins C (III), D (IV), E (V) and F (VI), the minor components of the carbazomycin complex, were isolated from the cultured broth of Streptoverticillium ehimense together with carbazomycins A (II) and B (I). Among them, III and IV were shown to be new substances and their structures were elucidated as 4-hydroxy-3,6-dimethoxy-1,2-dimethylcarbazole and 3,4,6-trimethoxy-12-dimethylcarbazole, respectively, by spectroscopic and chemical means. The other components, V and VI, were found to contain an aldehyde function and were identified as carbazomycinal and 6-methoxycarbazomycinal, respectively. The antimicrobial activity of III and IV are also reported.