Alkamide levels in Echinacea 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.