Separation of Ginkgolide Homologues by Liquid-Liquid Extraction Using Ionic Liquid As Extractant

Gingkgolides are unique natural compounds isolated from the leaves and root bark of Ginkgo biloba L.. They have shown to have a specific and selective antagonism of the platelet-activating-factor (PAF) receptor, of which GB is considered the most active one. Their chemical structures differ only in the number and position of the substituted hydroxyl groups. The intramolecular hydrogen bonding of the hydroxyls at C-1 and C-10 makes them more difficult to be separated. In this study, liquid-liquid extraction method for the separation of ginkgolides A, B and C was performed using ionic liquid as extractant and water as diluent. The results suggest that the  distribution coefficients of ginkgolides between the extraction phase and reffinate phase are most likely attributed to the hydrophobic interactions between ionic liquid and ginkgolides while the selectivity coefficients, are influenced by the dipolarity/polarizability and hydrogen bond basicity of the extraction solute.