Isolation and characterization of a novel polyether antibiotic of the pyrrolether class, antibiotic X-14885A

Antibiotic X-14885A is a polyether antibiotic belonging to the class of these natural acid ionophores known as pyrrolethers. The structure of the antibiotic was elucidated by X-ray crystallographic analysis of the hydrated sodium salt, which crystallized as a tetramer containing four antibiotic and water molecules and four atoms of sodium. Antibiotic X-14885A differs from the most well-known member of the class, A-23187, in two respects: the aromatic N-methylamino group present in the latter is replaced by a phenolic hydroxyl, and one of the four aliphatic methyls is replaced by a proton. Antibiotic X-14885A is active against Gram-positive bacteria and the spirochete, Treponema hyodysenteriae.