Salinity-induced changes in caffeic acid derivatives, alkamides and ketones in three Echinacea species

A hydroponic study was carried out to investigate the changes in caffeic acid derivatives, alkamides and ketones in three Echinacea species in response to salinity stress (0, 50, 75 and 100 mM NaCl). These hydrophilic and lipophilic compounds were extracted from the roots by Accelerated Solvent Extractor and analyzed simultaneously by RP-HPLC. The characteristic phytochemical profile of caffeic acid derivatives, alkamides and/or ketones was not affected by salinity. However, significant changes in their relative amount were found depending on the species and salinity intensity. Two of the Echinacea species studied, Echinacea purpurea and Echinacea angustifolia exposed to salinity up to 75 mM NaCl for two weeks, had higher amount of caftaric acid, cynarin, and cichoric acid (E. purpurea) as well as chlorogenic acid, cynarin, echinacoside, caffeic acid and alkamides 12, 13, 14/15, 16, 17, 8/9, 18 (E. angustifolia) than the respective control plants. In contrast, in Echinacea pallida, caftaric acid, echinacoside, and major ketones 22, 24, 25 and pentadeca-8Z, 11Z-dien-2-one levels were reduced at 50 and/or 75 mM NaCl. The highest concentration of salt (100 mM NaCl) reduced the level of cynarin, cichoric acid, cichoric acid derivative and alkamides 1, 3, 6, 7, 8/9 in E. purpurea and caftaric acid, alkamide 2, ketones 24, 25 in E. pallida, as well as alkamides 1, 2, 11 in E. angustifolia. Our results suggest that the quality of the raw material obtained from both E. purpurea and E. angustifolia exposed to salinity up to 75 mM NaCl would be higher than the one obtained from E. pallida as the plants retained most of their phytochemical marker compounds.

► Our study shows the first evidence of salt induced changes in alkamides and ketones in Echinacea.
► Quantitative changes in caffeic acid derivatives, alkamides and ketones varied depending on the species and salinity intensity.
► Echinacea purpurea and Echinacea angustifolia exposed to NaCl up to 75 mM, retained or increased most of their marker compounds.
► Quality of raw material was higher in salt-stressed E. purpurea and E. angustifolia than in Echinacea pallida.