Pyrrolo (1,4) benzodiazepine antitumor antibiotics: Biosynthetic studies on the conversion of tryptophan to the anthranilic acid moieties of sibiromycin and tomaymycin.

Biosynthetic intermediates between tryptophan and the anthranilate moieties of tomaymycin and sibiromycin have been suggested, based upon a combination of feeding experiments with either carbon-14-labeled substrates or competition experiments between radiolabeled tryptophan and unlabeled intermediates. In the case of sibiromycin and tomaymycin, substitution of the aromatic ring most likely takes place at the kynurenine stage. Feeding experiments with the anthramycin culture were inconclusive, most likely because of the cell impermeability.