Preparative Enantiomer Separation of Gossypol as Chloramphenicol Derivative With Cyclodextrin as Chiral Selector by High Speed Countercurrent Chromatography

This study proposed a general strategy of "pre-column derivatization-chiral selector synergy" and achieved preparation-level separation in the gossypol derivative system for the first time. In this study, gossypol acetate was derived by chloramphenicol base (d-(-)-threo-1-(p-nitrophenyl)-2-amino-1,3-propanediol), and the derivatives were separated by high-speed countercurrent chromatography using HP-β-CD (Hydroxypropyl-β-cyclodextrin) as chiral selector. According to the test results, a two-phase solvent system with a volume ratio of 7:13:8:12 water: methanol: ethyl acetate: cyclohexane was selected. The factors influencing the separation process were investigated. The final conditions are 65% methanol content in aqueous phase, 60% ethyl acetate content in organic phase, HP-β-CD concentration was 0.05 mol/L, pH value was 2.37, and temperature was 20°C. The purity of the enantiomers of gossypol acetate is more than 95% (it was calculated by the area normalization method), and the recoveries of gossypol derivatives are between 80% and 90%.