A quantitative profile of seasonal variations of alkylamides and phenolics in organically treated Echinacea purpurea (L.) Moench

Echinacea purpurea is consumed as a natural health product around the world. Due to the genus' ethnobotanical relevance, the phytochemistry of Echinacea has been extensively studied, revealing a variety of bioactive metabolites including caffeic acid derivatives and alkylamides. Whereas seasonal trends in root chemistry have been established, trends in other plant parts are relatively understudied. Similarly, few studies have evaluated the effects of organic plant growth substances in field trials. With increased demand for organic products, industry is looking for alternative ways to optimize yields of medicinal properties. For this study, we aim to quantify the concentrations of E. purpurea's secondary metabolites across organic treatments throughout the plant's first growth year to determine optimal harvesting time and conditions in all parts of the plant. Plants were grown in field plots treated with four different organic fertilizers: chicken waste, high cytokinin, low cytokinin, and fish oils; samples were collected biweekly from May-September. Dried plants were separated into major plant parts and were extracted exhaustively in EtOH. Using HPLC, concentrations of alkylamides and select caffeic acid derivatives were quantified in all samples and compared across plant part, developmental stage, and organic fertilizers. It was determined that while there were no major differences between treatments, phytochemical concentrations changed throughout the season in all plant parts; revealing that aerial parts of the plant also contain high levels of secondary metabolites and should not be excluded from future studies. The results of this study will not only aid in industry's yield optimization but will increase the understanding of E. purpurea's chemistry and physiology.

No conflict of interest has been declared by the author(s).