RESUMO
A separation technology of catalpol from Rehmannia with macroporpus adsorbent resins was investigated. The content of catalpol in the extract was determined by high performance liquid chromatography (HPLC). Nine different kinds of macroporous adsorbent resins were studied on the static capacity of adsorption and desorption, and D101 resin was best for the separation of the extraction solution of Rehmannia. The results showed that D101 resin had the highest static adsorption capacity of 69.2mg/g dry resin and its isotherm curve can be well described by Langmuir and Freudlich equation. The 5% ethanol elution on removal of the solvent under reduced pressure provided a brown powder, which was subjected to an open column chromatography on silica gel eluted with a CHCl3–MeOH gradient. The fraction eluted with CHCl3-MeOH (8∶2) was identified as catalpol and the purity of the compound was more than 90% purity by HPLC analysis. The yield of this separation technology was 6%.
