title: Noboritomycins A and B, new polyether antibiotics.
abstract: Noboritomycins A 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 C43/63O14Ag. 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 ethylester group. 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).
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000302:isolation & purification / Q000494:pharmacology; D055598:Chemical Phenomena; D002621:Chemistry; D004987:Ethers / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology; D005285:Fermentation; D007476:Ionophores / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D013302:Streptomyces / Q000145:classification / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004987:Ethers; D007476:Ionophores