Tetronomycin, C34Hsu08, isolated from a strain of Streptomyces sp. nov. represents a novel
A novel series of bis(acridines) has been synthesized in which the two potential intercalating chromophores are separated by symmetrical amide-linked chains varying in both length and conformational flexibility. By comparison to a monointercalating adduct, mono- vs. bis-intercalative behavior has been established for the bis(acridines). Spectrophotometric (visible, circular dichroism, and fluorescence) and viscometric (linear sonicated and closed circular superhelical DNA) experiments indicate that a highly rigid 8.8 A separated bis(acridine) monointercalates, whereas the longer and more flexible bis(acridines) are capable of bis-intercalation. In addition, spectrophotometric studies suggest a correlation between the tendency of intramolecular association and the ability to bis-intercalate. The results are in agreement with predictions based on the neighbor-exclusion principle and indicate that connecting chain rigidity is capable of playing a determining role in the mono- vs. bis-intercalation mechanism.
NoboritomycinsA and B, two new polycyclic ionophoric polyethers were isolated from a strain of Streptomyces noboritoensis. The crystal structure and absolute configuration of noboritomycin A were established by X-ray analysis of its silver salt C43H63O1,Ag. Noboritomycin A is the first metabolic polyether possessing two carboxylic acid functions on the carbon backbone (C-31), namely a free acid and an additional carboxylic acid ethylestergroup. An unusual spiroketal system as well as a salicylic acid chromophore represent further remarkable elements. Noboritomycin A shows in this respect a structural relationship to salinomycin and lasalocid respectively. Comparison of physico-chemical data, in particular the interpretation of the 1H-and 13C-NMR spectra, revealed that noboritomycins A and B are structurally closely related, noboritomycin B carrying an ethyl substituent on the aromatic ring in the place of a methyl group present in noboritomycin A. Both metabolites exhibit activity against Gram-positive bacteria and against Eimeria tenella (chicken coccidiosis).In the course of our screening for new antibiotics from soil actinomycetes we isolated a strain of Streptomyces noboritoensis (NRRL 8123) which produced two metabolites effective against Grampositive bacteria. The active compounds designated as noboritomycins A and B were characterized as carboxylic acid ionophores and represent new members of the polyether antibiotic group.') This report deals with the taxonomy of the producing strain, as well as fermentation, isolation, structure and biological activities of noboritomycins A and B.
Mutalomycin is a new metal-complexing polyether antibiotic produced by a strain of Streptomyces mutabilis NRRL 8088. The metabolite, a monocarboxylic acid, was isolated as the sodium salt C41H69NaO12. The structure of this polyether was established by X-ray analysis of its potassium salt C41H69KO12. Mutalomycin contains six heterocyclic rings and is structurally related to nigericin. The metabolite is active against gram-positive bacteria and Eimeria tenella (chicken coccidiosis). In the course of our search for new antibiotics from soil actinomycetes a strain (S 11743/A) of Streptomyces mutabilis was isolated which produced a metabolite effective against gram-positive bacteria and chicken coccidiosis. The active compound S 11743/A-1 designated as mutalomycin is a new member of the polyether antibiotic group. This report presents the taxonomy of the producing strain, as well as the fermentation, isolation, characterization and biological activities of mutalomycin.
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