GB862685A - New antibiotic designated pa 155a - Google Patents

Abstract

<PICT:0862685/IV (b)/1> An antibiotic designated PA 155A is produced by cultivating a PA155A - producing strain of Streptomyces Albus e.g. S. Albus ATCC 126 48 in an aqueous nutrient medium containing a source of carbon, organic nitrogen and inorganic salts under aerobic and especially submerged aerobic conditions. The temperature of cultivation is 23 to 32 DEG C. and preferably 26 to 30 DEG C., the pH is 6 to 7 and the duration of cultivation 1 to 3 days. Specified carbon sources are sugar, starch and glycerol; organic nitrogen sources are soybean meal, cottonseed meal, peanut meal and corn steep liquor; mineral salts are sodium chloride, sodium nitrate, magnesium sulphate and potassium phosphate. A buffer such as calcium carbonate or potassium dihydrogen phosphate may also be present. The antibiotic PA155A is isolated from the clarified broth by (a) solvent extraction (b) absorption on cation exchange resins (c) column chromatography on acid washed alumina. In one method, the filtered broth is extracted with ethyl acetate, the extract concentrated and a mixture of PA 155A and another antibiotic PA 155B precipitated by the addition of a non-solvent such as petroleum ether. A third antibiotic PA 155X remains in the residual clarified broth. Further purification of the mixed PA 155A and B is obtained by column chromatography on acid washed alumina. Alternatively, the residue obtained by removing the solvent from the ethyl acetate extract is subjected to countercurrent distribution between benzene, methanol and water (2:1:1), the PA 115A being recovered from the aqueous layer and the PA 115B from the organic layer. PA 155X is recovered from the filtered broth by treatment with a strongly acid cation exchange resin in the hydrogen form e.g. "Amberlite" 1R-120 (Registered Trade Mark) to adsorb the PA 155A and B and then neutralising the acidic effluent by passing it through a weakly basic anion exchange resin in the hydroxyl form e.g. Amberlite 1R-4B, the final effluent being concentrated and freeze dried. PA 155A is active against gram positive and gram negative microorganisms; it is basic forming salts with both inorganic and organic acids such as hydrochloric, phosphoric, nitric, sulphuric, tartaric, glycolic, citric, glucomic, malic, maleic, succinic, glutaric, acetic, benzoic and picric acids; melting point 209-210 DEG C.; optical rotation [a ]D25= -214 DEG (C=2% methanol); contains carbon 65,7%, hydrogen 6,0%, nitrogen 16,2%, oxygen 12,1% (by difference) C-CH3 5,44%; ultraviolet absorption spectrum in methanol shows maxima at 218, 273, 281 and 288 mu with E 1% cm of 1960, 200, 233 and 186; infra red absorption spectrum shows maxima at 3.20, 3.36, 3.46, 5,82, 6.15 to 6.35, 6.67, 6.84 to 6.93, 7.08, 7.30, 7.46, 7.75, 7.86, 7.94, 8.20, 8.67, 8.91, 9.01, 9.16, 9.29, 9.53, 9.85, 10.09, 10.46, 10.78, 11.36, 11.81, 12.22, 12.81, 12.93, 13.04, 13.38, 13.42 and 13.47 to 13.56 microns. It is sparingly soluble in water, chloroform, ether, ethyl acetate and benzene, more soluble in acetone and alcohols. Specification 692,066 is referred to.ALSO:A pharmaceutical composition comprises the antibiotic PA 155A (see Group IV (b)) together with a pharmaceutical carrier. Other drugs such as antibiotics and steroids may also be present. The preparations may be in the form of tablets or liquid preparations. Specification 692,066 is referred to.