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Semi-preparative separation and purification of taxol analogs by high-speed countercurrent chromatography.

High-speed countercurrent chromatography (HSCCC) was applied to the semi-preparative separation of taxol and its analogs, such as cephalomannine and 7-epi-10-deacetyltaxol from the extract of the bark of Taxus yunnannesis. The experiments were performed with a quaternary two-phase solvent system composed of n-hexane-thyl acetate-ethanol-water through two steps. In the first step, the four components were separated into two groups at a volume ratio of 1:1:1:1 and, in the second step, two components in each group were separated at different volume ratios of 3:3:2:3 or 4:4:3:4. The present method also allows consecutive injections with reproducible results. HPLC analysis showed that the purity of the four components obtained from a partially purified sample, containing taxol at 10%, ranged from 85 to 99%. The results indicated that HSCCC can be effectively used for the semi-preparative separation and purification of taxol and its analogs.