ISOLATION OF COLISTIN-A AND COLISTIN-B USING HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY

High-speed countercurrent chromatography was successfully applied to t he isolation of colistin-A and colistin-B from a commercial colistin p reparation. As the first step, TLC and HPLC analysis conditions for th e colistin components were established. Using these techniques, a two- phase solvent system composed of n-butanol-0.04M aqueous trifluoroacet ic acid (TFA) (1:1) was selected for high-speed CCC, where the concent ration of TFA was the major factor in controlling the partition coeffi cients of the colistin components. Yields of colistin-A and colistin-B were 9 mg each from 20 mg of the commercial sample, and the purity of each component was over 90 %. Fast atom bombardment (FAB) mass spectr ometry was utilized to confirm the nature of the isolated components.