GB708159A - A new antibiotic (erythromycin) and a process for preparing same - Google Patents

Abstract

An antibiotic, erythromycin, active against gram positive and gram negative microorganisms, Rickettsial bodies and large viruses is produced by cultivating an erythromycinproducing strain of Streptomyces erythreus, which is described, or a mutant thereof, in a culture medium containing assimilable sources of carbohydrate, nitrogen and inorganic salts. Cultivation is either surface (5-10 days) or submerged (2-5 days) with aeration at 25-37 DEG C., preferably 26-30 DEG C. The medium is adjusted to pH 6.0-7.5, preferably 6.5. Specified carbohydrates are starch, glucose, sucrose, and molasses. Nitrogen sources are corn steep solids, soybean meal, distillers' solubles, casein, amino acid mixtures, brewers' yeast and peptones, nitrates and ammonium salts. Inorganic salts are such as yield the ions sodium, potassium, calcium, phosphate, chloride, sulphate and cobalt. Erythromycin is isolated by (a) extraction with substantially water-immiscible solvents, e.g. alkyl esters of fatty acids, e.g. ethyl acetate and amyl acetate, chlorinated hydrocarbons, e.g. chloroform and ethylene dichloride, alcohols such as butyl alcohol, ketones such as methyl ethyl ketone, and ethers such as diethyl ether and dibutyl ether; and by (b) adsorption on, e.g., activated alumina, silica gel, magnesium aluminium silicate and activated carbon (which has been pretreated with acetic acid to reduce the bonding between the antibiotic and the carbon), and elution therefrom with a solvent such as 50 per cent methanol in benzene. Extraction or adsorption is at pH 9.0-10.0, preferably 9.5. Below this pH erythromycin complex forms. Salts are prepared by treating an aqueous solution of erythromycin with the appropriate acid. Specified salts are the hydrochloride, sulphate, citrate, mandelate, oleate, palmitate, myristate, stearate and oxalate. Erythromycin base has the analysis: C=60.4 per cent, H=9.26 per cent, N=2.07 per cent, and O= 28.27 per cent. It is a crystalline nitrogenous base, melting at 136-140 DEG C., having molecular weight of 725; [a ]25D=-78 DEG (C=1.99 ethanol); soluble in alcohol, acetone, chloroform, acetonitrile and ethyl acetate, less soluble in water, ether, ethylene dichloride and amyl acetate; pKa=8.8 when titrated in 2 : 1-dimethyl formamide-water solution; refractive indices in sodium light at 27 DEG C., n1=1.452, n2=1.473; ultra-violet-absorption spectrum characterized by a single broad peak-of-intensity having a maximum at 280 mm at pH 6.3; X-ray diffraction pattern and infra-red absorption spectrum given. Erythromycin hydrochloride forms needles melting at 170-173 DEG C., very soluble in water and alcohols, sparingly soluble in ether, amyl acetate and chloroform, has characteristic infra-red absorption spectrum. Erythromycin complex forms needles melting at 82-83.5 DEG C.; soluble in acetone, alcohols, chloroform and ethylene dichloride; slightly soluble in ketones and ethers; molecular weight 1130; [a ]25D= - 47 (C=2 per cent ethanol); contains C=64.71 per cent, H=10.23 per cent; N=1.35 per cent, O=23.71 per cent; ultraviolet absorption spectrum shows one maximum at 274 mm <FORM:0708159/IV (b)/1> =1.07; refractive indices in sodium light at 25 DEG C., n1=1.509, n2=1.499; X-ray diffraction pattern and infra-red absorption spectrum in chloroform is given. Specified strains of erythromycin-producing S. erythreus are NRRL-2338, NRRL 2359, NRRL 2360 and NRRL 2361.