| abstract |
The polycyclic ether antibiotics designated UK-41,637 and UK-44,579, their free acids and non-toxic cationic salts in addition to sodium, mixtures of them and dried fermentation broths containing them, are produced by culturing a strain of Actinomadura cremea. UK-41,637 is a sodium salt of the formula:- <IMAGE> UK-44,579 is a sodium salt with a close structural relationship to UK-41,637. It has a melting point of 90-93 DEG C, an optical rotation of alpha <25>589=37.4 DEG (c, 0.1, CH3OH), and is also characterised by its i.r. (KBr), <1>H and <13>CC n.m.r. spectra. |