A quantitative HPLC method for the quality assurance of Echinacea Products on the North American market

A rapid and quantitative method of quality assurance for marker phytochemicals in products containing material derived from Echinacea species has been developed. In order to assess the efficiency of extraction of phytochemicals from the roots and aerial parts of Echinacea purpurea and E. angustifolia, a study of solvent mixtures and extraction methods was carried out to determine the recovery of known compounds from plant materials. Ultrasonic extraction of dried samples with methanol:water (7:3) or ethanol:water (7:3) gave good yields of cichoric acid, echinacoside and the alkamides, undeca-2E,4Z-diene-8,10-diynoic acid isobutylamide and a mixture of dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamides (recoveries of 89%, 85%, 80% and 90%, respectively). The HPLC separation of the phenolic compounds cichoric acid, chlorogenic acid and echinacoside was also improved by careful attention to the pH of the mobile phase. A shortened HPLC column allowed turnaround times of 22 min for phenolic components and 15 min for alkamides with lower solvent use. Assessment of commercial raw materials from the North American market using the new method was useful for confirmation of species and showed a very large variation in concentration of markers in the products sold in this market.