Application of droplet counter-current chromatography to the isolation of natural products

Abstract

Droplet counter-current chromatography (DCC), a recently developed all-liquid separation technique, has been applied to the preparative separation of various classes of natural products. From a crude extract of Ajuga pyramidalis (Labiatae), several hundred milligrams of pure iridoid glycosides could be obtained within 8 h. The volume of mobile phase used for the elution was less than 150 ml. Another example dealilng with iridoid glycosides is given bythe isolation of several consittuents of a Castilleja species (Scrophulariaceae). DCC has also been used to separate xanthone-O-glycosides from a North-American Gentiana species (Gentianaceae) and the main alkaloids of an opium extract. Thin-layer chromatography (TLC) was found to be an ideal and quick method for the selectionof solvent systems.