Extraction of Fusidine with butyl acetate

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The isolation of Fusidine from native solutions is based on the ability of this antibiotic to transfer in acid form into an organic solvent, in particular into butyl acetate.

The isolation of Fusidine from native solutions is based on the ability of this antibiotic to transfer in acid form into an organic solvent, in particular into butyl acetate. The extraction of Fusidine by an organic solvent'is carried out from acidified aqueous solution [2-41. However the extraction of Fusidine from aqueous solutions at low pH values is attended by a series of difficulties: an increased tendency of the system towards emulsification, caused by denaturation of protein contaminants, and the comparatively low selectivity of the process.

The aim of the present work was to establish the influence of the pH of the aqueous phase at the time of extraction on the distribution of Fusidine and products accompanying it between the phases, and also on the stability of the emulsions obtained during extraction

Native solutions used in this work were obtained after separation of the mycelium from the culture fluid of Fusidiumcoccineumo Aqueous solutions of Fusidine, made by dissolving in water the sodium salt of the antibiotic of activity 877 ~g/mg were also used~ The content of fusidine in the initial aqueous phase varied from 500 to 5000#g/ml. Chemically pure butyl acetate was used as solvent. Cetazole was added as de-emulsifier to the native solution in experiments to determine emulsion stability. The determination of the distribution coefficient of Fusidine between aqueous phase and butyl acetate was carried out in a thermostatted vessel with a stirrer at a liquid volume ratio of 1:1 and a temperature of 20 • 2 ~ The duration of contact was 30 min. Preliminary experiments established that in practice equilibirum had been achieved in the system after this time, The pH of the aqueous phase was established by adding aqueous solutions of sulfuric acid or sodium hydroxide.

The content of Fusidine in the aqueous phase was determined by a microbiological method. For the analysis of butyl acetate solutions a depleting extraction of the antibiotic was carried out with an aqueous alkaline solution and subsequent determination of the Fusidine content in the re-extract. The intensity of coloration of the butyl acetate extracts was measured in a photoelectric colorimeter with a blue color filter in a cuvette of 30 mm thickness.

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