Agriculture Reference
In-Depth Information
Synonyms — Echinacea intermedia Lindl. ex Paxton., Helichroa purpurea (L.) Raf., Rudbeckia
purpurea L.
Family — Compositae
Common Names — Purple coneflower, E. angustifolia (D.C) Heller = coneflower, E. pallida
(Nutt) Britt. = black Sampson
Description — Echinacea is available in the market as roots or rhizomes, which are often
twisted with longitudinal furrows. It is grayish green in appearance, and the transverse section
reveals it is yellowish and porous with black patches. It is a slightly aromatic, has a somewhat sweet
taste at first, then bitter, and leaves an aftertaste that gives the tongue a peculiar tingling sensation.
Although the individual species are botanically very distinct, the drug is treated as one product
since the major difference lies in the quantity and type of the minor metabolites. Moreover, much
confusion exists regarding the species specificity in some of the published data.
Habitat and Distribution — The plant is indigenous to North America, from which it has been
introduced as a cultivated medicinal plant in parts of northern and eastern Africa.
Constituents — Polysaccharides, mainly heteroxylans and norrhamanogalactans, have been
isolated from the genus. 524 A triglycoside of a caffeic acid derivative, called echinacoside, has
been found present in E. angustifolia, but not in E. purpurea ; some alkanes and flavonoids were
also found in the species. 525 The essential oil contains caryophyllene, germacrene D, methyl- p-
hydroxycinnamate, and humulene. 526,529 The dried roots of E. pallida yielded polyacetylenes that
were absent in the fresh plant material, and it has been suggested that these polyacetylenes could be
artifacts generated during storage of the drug. 527,528 Other constituents found in Echinacea include
unsaturated isobutyl amides (e.g., echinacin), the alkaloids tussilagine and isotussilagine, a labdane
derivative, and vanillin linolenic acid derivatives. 123 It has been observed that commercial samples
of the drug are sometimes adulterated with American feverfew ( Parthenium intergrifolium L.), and
some of the compounds reported from commercial samples, especially the sesquiterpene esters,
may be due to the adulterant. 123,531
The immunostimulant activity of Echinacea appears to have been known to earlier scientists
since as early as 1831 the German scientist Dierbach was said to have indicated its use as an immu-
nostimulant and for healing damaged skin tissues. A modern account of its immunostimulant activ-
ity was given by Wagner and his colleagues, 529 who showed the polysaccharide fraction of the
aqueous extract of the plant possessed in vitro and in vivo immunostimulant activity. In the carbon
clearance test in mice, it was shown that the oral administration of the drug enhanced phagocytosis;
also, in the in vitro granulocyte assay, it stimulated phagocytosis. The lipophilic fractions of the
extract were more active than the polar fractions. 530 It has also been shown that an acidic arabino-
galactan with molecular weight of 75,000, isolated from cell cultures of E. purpurea, was effective
in activating to produce TNF-α, interleukin 1 (IL-1), and interferon β 2 . 531 It does appear from the
report that the acidic arabinogalactans were more active than neutral arabinogalactan. It was also
found that although arabinogalactan possessed immunostimulant activity, it neither activated B
cells nor induced the T cells to produce IL-2, interferon B 2, or interferon γ, but it did induce a slight
increase in T-cell proliferation. 531 The purified polysaccharides from the cell cultures of the plant
were effective in protecting mice against the lethal effects of infections with one predominantly
macrophage-dependent and one predominantly granulocyte-dependent pathogen, Listeria monocy-
togenes and Candida albicans, resp e ct ively. 532
Clinical Properties — Echinacea species are employed in clinical medicine as anti-inflam-
matory agents and as immunostimulants. 533,534 It has been shown that a single dose of the drug per
week as a therapeutic adjuvant is adequate for the production of phagocytosis, as evidenced by lym-
phokine production and assay using [ 3 H]-thymidine incorporation and a skin test with antigen. 534
The drug is marketed all over Europe as an ingredient in several proprietary anti-infective drugs.
Esberotox N and Echinichin, two of the most common brands, have been shown to be most useful
in phagocytosis-dependent metabolism and therapy. 535
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