Purification of Alkylamides from Echinacea angustifolia (DC.) Hell. Roots by High-Speed Countercurrent Chromatography

Abstract

High-speed countercurrent chromatography (HSCCC) was used for the separation of alkylamides from the roots of Echinacea angustifolia (DC.) Hell. For this purpose, the alkylamides were extracted with hexane and subjected to semipreparative HSCCC using a two-phase solvent system consisting of n-hexane, ethyl acetate, methanol, and water (4:1:2:1). The lower aqueous phase was used as the mobile phase at a flow rate of 3 mL/min and a rotary speed of 1000 rpm. This procedure led to the isolation of four pure alkylamides, that is, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide (38.9 mg, 97% purity), dodeca-2E,4E,8Z-trienoic acid isobutylamide (4.4 mg, 92% purity), dodeca-2E,4E-dienoic acid isobutylamide (3.2 mg, 99% purity), and dodeca-2E,4E-dienoic acid 2-methylbutylamide (0.3 mg, 92% purity). The identity and purity of the isolated alkylamides were confirmed by LC-ESI-MS and (1)H NMR and (13)C NMR data. To the best of the authors' knowledge, this is the first report of dodeca-2E,4E-dienoic acid 2-methylbutylamide in E. angustifolia roots.