Harvest strategies for optimization of the content of bioactive alkamides and caffeic acid derivatives in aerial parts and in roots of Echinacea purpurea

Aerial parts and roots of Echinacea purpurea were harvested consecutively in order to find the best strategy for harvest of both types of plant material for an optimal content of bioactive alkamides and caffeic acid derivatives. Four caffeic acid derivatives and 15 alkamides were identified and quantified. The aerial parts were harvested in bud, bloom, and wilting stage and the roots were harvested 1 week, 1 month, and 3 months after each harvest of aerial parts. The highest yield per area of both alkamides and caffeic acid derivatives is achieved when the aerial parts are harvested late (wilting stage). To obtain an optimal content of alkamides and caffeic acid derivatives it is not recommendable to harvest the aerial parts and the roots in the same year. If the aerial parts must be harvested, the roots should be harvested 1 week after because this will result in the most optimal concentration of bioactive compounds in both products.