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Recommendations for selection efforts to improve the therapeutic quality of Echinacea angustifolia crops in British Columbia Boucher, Alain

Abstract

For over a century, documented scientific research and debate has revolved around the therapeutic properties of the medicinal plant Echinacea angustifolia. With overwhelming evidence demonstrating the biological activity of its root phytochemical constituents, the genetic improvement of E. angustifolia by selecting phytochemically rich genotypes has garnered both scientific and commercial interest. This dissertation presents results of multi-disciplinary experiments intended to help establish scientifically based guidelines for breeding efforts aimed at developing therapeutically superior varieties of E. angustifolia in British Columbia. Cultivated E. angustifolia populations from British Columbia and Washington were grown in a common greenhouse environment to identify possible genetically superior populations with respect to root concentrations of therapeutically relevant caffeic acid derivatives (CAD) and alkamides. However, none of the studied cultivated E. angustifolia populations showed significant genetic differences in terms of root phytochemical traits. In the second part, an investigation into correlations between root and shoot phytochemical concentrations in field- and greenhouse-grown plants revealed that concentrations of therapeutically relevant marker compounds in shoots were generally poor predictors of concentrations in roots. Some weak yet significant positive correlations were observed between root and shoot concentrations of CADs but were inconsistent between the two environments. Significant genotype by environment interactions were documented for the first time in phytochemical traits of E. angustifolia in a study of five genetically homogeneous populations grown in three different environments, including 1 greenhouse and 2 field sites in British Columbia. For the final objective, in vitro bioassays showed that environmentally and genotypically related differences in concentrations of CADs and alkamides in E. angustifolia ethanolic root extracts did not translate into significant differences in their anti-inflammatory potential as measured by pro-inflammatory interleukin (IL-6 and IL-8) secretion in human bronchial epithelial (BEAS-2B) cells challenged with rhinovirus. When used in isolation however, pure tetraene alkamide showed a significant inhibitory effect on secretion, thereby further supporting the use of high alkamide production as a selection criterion for therapeutic E. angustifolia cultivar development. A series of recommendations derived from these findings are presented along with ideas for important future studies in the field of Echinacea research.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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