The taxonomy, phytochemistry and biological activity of the genus Echinacea (Asteraceae).

Title: The taxonomy, phytochemistry and biological activity of the genus Echinacea (Asteraceae).
Authors: Binns, Shannon E.
Date: 2001
Abstract: Echinacea Moench (Asteraceae) is a native North American plant genus with a long history of use as phytomedicine in both the Indigenous and European traditions (Shemluck 1982; Bauer 1998). A taxonomic revision of the genus Echinacea was conducted for the first time using morphometric analysis of natural populations sampled throughout the entire genus range. Individual plants were grouped without a priori taxonomic labeling, by morphological similarity using non-hierarchical and hierarchical, agglomerative clustering strategies. Canonical discriminant analysis (CDA) supported the distinction of two new subgenera, four species and eight varieties in the genus according to overall morphological similarity. When the same dataset was labeled a priori according to McGregor's taxonomy (I968), his taxa were supported (with the exception of one variety) at the variety level. The new morpho-taxa were sufficiently distinguished by CDA of phytochemical variation (except for two varieties). Also, a class of outliers (including artificial hybrids) was not supported in either dataset as a taxon, and was therefore classified as 'hybrids/introgressants'. In the most parsimonious cladistic solution, one new subgenus was basally divergent to a clade of all others (70% bootstrap value) and all (four species were distinguishable by at least one synapomorphy. Phytochemical profiles and average content of each known compound were reported here for the first time from all taxa of Echinacea, and revealed that five diene alkamides, one polyyne and two phenolic compounds (cichoric acid and echinacoside) were all chemotaxonomic markers within the genus Echinacea. Some of the same chemotaxonomic markers contributed heavily to the quantitative multivariate analysis of 26 phytochemicals, which identified five chemotypes among nine wild populations of the revised E. pallida var. angustifolia in a controlled greenhouse study. The alkamides and polyynes were also induced to higher concentrations in young roots of E. pallida (Nutt.) Nutt., that were sprayed with methyl jasmonate. Furthermore, plant extracts of the Echinacea taxa were variably phototoxic to clinically relevant pathogenic fungi, such as Candida spp. The different phototoxic activities between Echinacea taxa reflected the observed phytochemical variation, especially in the polyynes. Antiviral activity to Herpes simplex was linked to the presence of polyynes and cichoric acid in fractionated Echinacea root and inflorescence extracts.
CollectionTh├Ęses, 1910 - 2010 // Theses, 1910 - 2010
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