Quantitative elimination of Flavokavines A and B from Kava Kava (Piper methysticum G. Forst) by isoelectric focused adsorptive bubble separation.

Adsorptive bubble separation, though still rarely used, is a suitable method for enrichment of surface-active macromolecules such as enzymes and proteins. There is a lack of investigations with small molecules, which can also be separated from complex mixtures by this method. In this work, an aqueous extract of Kava Kava ( Piper methysticum G. Forst) was used as a model system. Enrichment of undesirable Flavokavine A (7) and Flavokavine B (8) in the foam was influenced by the pH value, the amount of saponin as surface active substance, and the flow rate of the foam-forming gas. Efficiency was highest with diluted samples at pH 6.5. Under these conditions, transfer of Kavapyrone (1-6) to the foam was negligible.