GB672510A - Improvements in or relating to the purification of aureomycin - Google Patents

Abstract

Aureomycin in the form of an acid salt is isolated from an aqueous aureomycin solution, having a pH of less than 4 and containing at least 0.3 mg. of aureomycin per ml., by adding to such a solution a water-soluble inorganic salt and a mono- or poly-hydric alcohol or an ester or ether thereof as solvent for the aureomycin the amount of salt being preferably substantially sufficient to saturate said aqueous solution and the amount of organic solvent being preferably insufficient to appreciably dissolve or extract the aureomycin, and separating the resulting acid salt of aureomycin. It is preferred that the aureomycin concentration be 0.3 to 30 mg. per ml., the pH between 1 and 4 and the organic solvent butanol in the proportions of not more than 10 per cent, and preferably 5 per cent, by volume. The aureomycin solution may be prepared from the fermentation mash of Streptomyces aureofaciens or other aureomycin producing organism by: (a) acidifying the mash with mineral acid to a pH below 4, adding a filtration aid, e.g. fuller's earth, filtering and evaporating the filtrate in vacuo below 50 DEG C. and preferably between 20 DEG and 40 DEG C.; (b) treating the mash with calcium, strontium, barium or magnesium ions at a pH 6 to 11, and preferably 7 to 9, adding fuller's earth and filtering, the cake so formed being extracted with mineral acid and the extract concentrated as in (a); and (c) extracting the mash with a water-miscible organic solvent containing mineral acid, e.g. ketones, such as acetone and aliphatic alcohols such as ethanol, removing the solvent from the extract and concentrating the extract as in (a). The organic solvents for the aureomycin which are used in the formation of the acid salts may be anhydrous ethanol, methanol, isopropanol, b -ethoxyethanol, n-butanol, sec.-butanol, amyl alcohol, hexyl alcohol, capryl alcohol, octyl alcohol and decanol, of which the substantially water-insoluble solvents are preferred. The inorganic salts may be sodium chloride, ammonium chloride, lithium chloride, potassium chloride, calcium chloride, sodium sulphate, ammonium sulphate, lithium sulphate, disodium hydrogen phosphate and potassium dihydrogen phosphate, of which the chlorides are preferred.