Increase in the content of secondary metabolites and antioxidant activity in purple coneflower (Echinacea purpurea) induced by seed treatment with physical stressors

Abstract

Purple coneflower, Echinacea purpurea (L.) Moench., is one of the most widely used medicinal plants and dietary supplements. Numerous attempts have been made to meet increasing demands in production of the commercially important plant biomass and to optimize composition of pharmaceutical products, including biotechnological approaches. We studied the effects of pre-sowing seed treatment, using vacuum (7 min), radio-frequency electromagnetic field (5-15 min) and cold plasma (2-7 min), on germination and growth of Echinacea purpurea by using germination tests, estimating plant morpho-physiological parameters, detecting certain metabolites and radical scavenging activity in leaf extracts. All applied treatments induced earlier and faster germination of E. purpurea seeds. Cold plasma and electromagnetic field did not change the final germination percentage, and it was decreased after vacuum treatment. The plants grown from all groups of treated seeds had larger height, developed more leaves, whereas some treatments substantially increased root weight. The content of vitamin C and phenolic acids in extracts of plant leaves from the treated groups was substantially higher in comparison to the control: the amount of cichoric acid per plant increased up to 3.8-fold, and amount of vitamin C per plant – up to 1.9 fold. Seed treatments induced an increase in radical scavenging activity (up to +114%) in leaf extracts. [...]