抄録
Carbazomycins A (II) and B (I), the first antibiotics having a carbazole nucleus, were produced by Streptoverticillium ehimense and inhibit mainly the growth of phytopathogenic fungi. Their structures were determined by spectral and chemical means including X-ray analysis. The present paper describes the biosynthetic studies on the major component, carbazomycin B (I), performed by feeding experiments with ^<14>C- and ^<13>C-labeled precursors followed by ^<13>C-NMR measurements. The results summarized in Fig. 7 indicate that tryptophan is incorporated into the ten carbons of the carbazole nucleus of I except for C-1 and C-2, the methoxyl group is introduced from methionine, C-1 and C-10 of I are derived from acetate, and C-2 and C-11 of I are derived from C-2 and C-3 of pyruvate or alanine which are also incorporated into C-1 and C-10 of I via acetate. During the biosynthetic studies of I, we found six minor components, carbazomycins C (III), D (IV), E (V), F (VI), G (VII) and H (VIII). Their structures have been elucidated by ^1H- and ^<13>C-NMR spectroscopy and chemical correlation, and the structures of III and VII have been confirmed by X-ray analysis. Carbazomycins G (VII) and H (VIII) have a unique structure with partly oxidized carbazole nucleus.
