Chapter two Supercritical fluid extraction of alkaloids

Abstract

This chapter reviews the supercritical fluid extraction (SFE) method as an extraction technique for alkaloids emphasizing the usage of basic modifiers. Till recently, most of the published work on the SFE of natural products was concerned primarily with nonpolar substances such as essential oils, lipids, flavor, and fragrance ingredients. However, recent reports have shown that some polar plant constituents such as flavonoid glycosides, proteins, and steroidal glycosides can be extracted by SFE as effectively as conventional organic solvent extraction. The chapter documents enhancements of the efficiency of SFE extraction of alkaloids from plant matrices using basified modifiers. The pure compound solubility of some free bases in pure supercritical CO 2 is measured by investigating the effects of temperature, pressure or density of CO 2 ; and the solubilities of the alkaloidal salts are compared with those of their free bases to evaluate the difference of their solubilities influenced by a changing from free bases to salts. Polar solvents such as methanol and water, as initial modifiers, are used for the enhancement of the solubilities and the solubilities of the salts by non-basified modifiers such as neat methanol or water are compared with those of methanol or water basified with diethylamine.