Philipp Krastel

Endophenazines A-D, New Phenazine Antibiotics from the Arthropod Associated Endosymbiont Streptomyces anulatus

Four new members of the phenazine family, endophenazines A-D, and the already known phenazine-1-carboxylic acid (tubermycin B) were detected in the culture broth of various endosymbiotic Streptomyces anulatus strains by chemical screening in a combination of TLC-staining reagents and HPLC-diode array analysis. The endosymbiotic strains were isolated from four different arthropod hosts at various sites. The new phenazine compounds showed antimicrobial activities against Gram-positive bacteria and some filamentous fungi, and herbicidal activity against Lemna minor (duckweed).

Biosynthetic Capacities of Actinomysetes. No.27. Endophenazines A-D, New Phenazine Antibiotics from the Athropod Associated Endosymbiont Streptomyces anulatus. II. Structure Elucidation.

A detailed screening of the secondary metabolite pattern produced by different athropod associated strains of the species Streptomyces anulatus resulted in the isolation and structure elucidation of the endophenazines A-D (2, 4-6). The structures were assigned by spectroscopic methods and chemical transformations. 4 represents a chromophoric system based on a phenazin-7-one, 5 and 6 are new 5, 10-dihydrophenazine derivatives.

Biosynthesis of the Antibiotic Echinosporin by a Novel Branch of the Shikimate Pathway

Echinosporin (1), a known antibiotic with a unique tricyclic acetal-lactone structure, is produced by Streptomyces erythraeus (strain Tu 4015), together with the novel 7-deoxyechinosporin (2) as minor compound, which was fully characterized. The biosynthesis of 1 was established by feeding experiments with 13C-labelled precursors. The results revealed that 1 was formed by the shikimate pathway, with chorismate as a biosynthetic intermediate. The proposed mechanism for the conversion of chorismate into 1 represents a new branch of the shikimate pathway, producing a nonaromatic metabolite. In addition, the influence of aromatic amino acids and of glyphosate, an inhibitor in the shikimate pathway of plants, was investigated. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)