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

ABSTRACT 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%.