Sugaring-out strategy for counter-current chromatography isolation: podophyllotoxins and flavones from Dysosma versipellis as examples

Abstract

Counter-current chromatography is an efficient and practical liquid–liquid chromatography technique for the separation and purification of complex mixtures such as natural product extracts and synthetic chemicals. However, counter-current chromatography is a challenging approach and requires special knowledge, especially for selection of the solvent system, which may be estimated as 90% of the entire amount of work. In this work, we introduced a sugaring-out strategy for optimizing two-phase solvent systems for counter-current chromatography by using sugars as additives. Thirteen podophyllotoxins and flavones in the extract of the Traditional Chinese Medicine Dysosma versipellis were selected as model compounds, and nine sugars, including sucrose, glucose, fructose, maltose, D-galactose, D-sorbose, mannose, rhamnose, and xylopyranose, were selected as modifiers added into the two-phase solvent systems. As a result, we found that almost all of the sugars used in this work could increase the values of the partition coefficients of almost all of targets in the two-phase hexane–ethyl acetate–methanol–water solvent systems. In addition, sugars with different chemical structures seemed to have different sugaring-out effects on the resolution and selective separation of some components of Dysosma versipellis, although they were able to increase the partition coefficients of several components. Therefore, it may be an alternative strategy to quickly obtain an optimal two-phase solvent system by adding some sugars into the selected two-phase solvent system. This method is very simple and efficient for the separation and purification of single or multiple targets from natural products.