Alkamide Levels inEchinacea purpurea: A Rapid Analytical Method Revealing Differences among Roots, Rhizomes, Stems, Leaves and Flowers

Abstract

A rapid extraction, clean-up, and RPLC procedure suitable for routine quantitative analyses of alkamide levels in Echinacea purpurea extracts is described. The ¹³C-NMR spectra of the main diene-diyne alkamides in E. purpurea are reported. Alkamide levels differed significantly among roots, rhizomes, stems, leaves, and flowers of E. purpurea. Roots were distinguished from other plant parts by higher levels of the C₁₂ diene-diyne alkamides, whereas levels of the C₁₂ tetraene alkamides and C₁₁ diene-diynes were highest in vegetative stems. The ratio of the two stereoisomeric C₁₂ tetraene alkamides differed between flowers and all other E. purpurea parts. These results are important for standardisation of medicinal preparations of E. purpurea.