The genus Echinacea, indigenous to North America, belongs to the aster family (Asteraceae) and includes nine different species (Anon. 1997a). Of these species, E. purpurea, the purple coneflower, is both most commonly used as a medicinal herb and intensively studied. Less popular species of the genus include E. pallida, the pale purple coneflower, and E. angustifolia, the narrow-leafed purple coneflower (Foster 1997, Anon. 1996).
According to one source, "Echinacea seems to have been used as a remedy for more ailments than any other plant" (Anon. 1997a). All parts of this plant have been used for medicinal purposes including snakebites, common colds, toothaches, sores, wounds, and herpes. Due to its demonstrated immune-boosting properties, current research is examining its potential to treat cancer, arthritis, AIDS, and chronic fatigue syndrome. In West Germany, more than 200 pharmaceutical preparations, including extracts, salves, and tinctures, are made from Echinacea plants (Anon. 1996).
Many of the active compounds in Echinacea plants are damaged or destroyed by processing. Therefore, the most effective way to preserve the healing properties is by freeze-drying (Anon. 1997c).
Chemical analysis of plants in the genus Echinacea has identified seven groups of medically important components including polysaccharides, flavonoids, caffeic acid derivatives, essential oils, polyacetylenes, alkylamides, and miscellaneous chemicals. In general, the water-soluble polysaccharides are most useful in stimulating the cellular immune system while the fat-soluble components enhance macrophage phagocytosis (Anon. 1997a).
Several polysaccharides possessing immunostimulatory and mild anti-inflammatory properties have been isolated from several Echinacea species. It appears that the immunostimulating effects of Echinacea result from polysaccharides surrounding tissue cells and thereby providing protection from bacterial and pathogenic invasion (Anon. 1997b). The polysaccharide components have also been shown to promote tissue regeneration by stimulating fibroblasts and inhibiting the enzyme hyaluronidase, which breaks down the intracellular cement called hyaluronic acid (Anon. 1997a).
The aerial portion of E. purpurea is rich in polysaccharides and the root of E. angustifolia contains high concentrations of inulin. Inulin activates the altemate complement pathway of the immune system thereby enhancing the movement of white blood cells into areas of infection, increasing solubility of immune complexes, and destroying bacteria, viruses, and other microorganisms. However, the most powerful immune-boosting polysaccharides are, most likely, the highly branched, water-soluble heteroglycans that contain a number of different sugars rather than polysaccharides like inulin that contain only polyfructose (Anon. 1997a).
Echinacea polysaccharides enhance macrophage phagocytosis and stimulate macrophages to produce several compounds important to the immune system (Anon. 1997a). Extracts from E. purpurea, containing purified polysaccharides, caused increased proliferation of phagocytes in spleen and bone marrow as well as the migration of granulocytes to the peripheral blood in vivo. In vitro, macrophages were stimulated to produce interleuken-1, interleuken-6, and the tumor-necrosis factor alpha, causing elevated amounts of reactive oxygen intermediates and inhibiting the growth of Candida albicans (Roesler et al. 1991a). Similar research indicates that polysaccharides isolated from cell cultures of E. purpurea caused macrophages to increase production of tumor-necrosis factor alpha. This enhances cytotoxicity against the tumor target as well as the intracellular parasite Leishmania enrietti (Steinmueller 1993). Although such studies have been performed in mice, the polysaccharides could induce acute-phase reactions and activate phagocytes similarly in humans (Roesler et al. l991b).
The most important caffeic acid derivatives include cichoric acid, chlorogenic acid, cynarin, and echinacoside. Echinacoside, the most beneficial compound, accumulates in the roots and appears in minute quantities in the flower (Anon. 1997a). This compound may be as effective as penicillin in killing a wide array of viruses, bacteria, fungi, and protozoa (Anon. 1997d). Echinacoside exhibits a protective effect against the free-radical induced breakdown of Type III collagen by allowing collagen to return to its native profile. These findings provide a rationale for the topical use of Echinacea extracts for both treatment and prevention of photodamage to skin by UVA/UVB radiation (Facino et al. 1995).
The alkylamides, found in greatest concentration in the roots of E. angustifolia, are said to have a mild anesthetic property. The alkylamides are responsible for Echinacea's characteristic tingling sensation on the tongue (Anon. 1997a).
Echinacea extracts have been used effectively to treat chronic upper respiratory tract infections. A double-blind, placebo-controlled study treated 108 volunteers with Echinacin liquid over an eight week period. In comparison to the placebo group, those who received Echinacin exhibited an increased time between infection, a shortened duration of illness, and less severe symptoms. In addition, 36% of Echinacin patients had no further infections (Anon. 1997a).
Echinacea may become a useful adjunct to cancer treatment. Depression of white blood cell levels during both radiation and chemotherapy may be treated using Echinacea. A study involving fifty-five radiation therapy patients revealed that 85% of those who were treated with E. purpurea simultaneously showed a stable white blood cell count while those without Echinacea showed a steady decline (Anon. 1997a). Carcinoma pahents given Echinacea extracts exhibited an increase of CD4+ cells, natural killer cells, and Lymphokine Activated Killer cells. Concurrently, the level of CD8+ cells declined (Lersch et al. 1990). Specifically, (Z)-1,8-pentadecadiene found in the root of E. angustifolia and E. pallida has been shown, in vivo, to have direct anti-cancer activity (Anon. 1997a).
Extracts of E. purpurea were used in combination with Panax ginseng to treat patients with AIDS and chronic fatigue syndrome. Results indicate that E. purpurea significantly increased antibody dependant cellular cytoxicity of peripheral blood mononuclear cells from all subject groups (Broumand et al. 1997).
The anti-inflammatory properties of Echinacea have proven useful in treating rheumatoid arthritis. In one study, fifteen drops of E. purpurea extract three times a day reduced inflamation by 21.8%. While this decrease is approximately half of that associated with cortisone or prednisone, no side effects were noted as observed in the steroids (Anon. 1997a). Use of one particular Echinacea extract causes a decrease in peroxide oxidation of lipidies and an increased antioxidant protection that appears to be lacking in patients receiving nonsteroid treatment (Hryzhak et al. 1994). Further studies have shown that immune-modulating activity caused an increase in Iymphocyte content and number of IgA antibodies. However, the number of IgM antibodies and circulating immune complexes were reduced (Babynina et al. 1994).
At the recommended doses or even in higher doses, no acute or chronic toxicity has been observed. In vitro and in vivo tests revealed no mutagenic activity. The only ill effect noted involves a slight fever as a result of the intravenous use of E. purpurea extracts. Such fevers are likely due to the production of interferon and interleukin-1 by stimulated macrophages (Mengs et al. 1991, Anon. 1997a). In some individuals, excessive use causes a strange scratchy, tickling feeling in the throat (Anon. 1996). Reports indicate that Echinacea should not be taken by individuals allergic to plants in the daisy family or individuals with autoimmune disease (Bricklin 1996).
Anonymous. 1996. Guide to Medicinal Herbs Online: Echinacea. http://www.egregore.com/herb/echinacea.html
Anonymous. 1997a. Dr. James Downey's Herbal Research and Healing. http://www.herbsinfo.com/pages/echin.html
Anonymous. 1997b. Echinacea. http://www.getset.com/uptown /echin.html
Anonymous. 1997c. Echinacea. http://www.mothernature.com/echin.html
Anonymous. 1997d. Immune System, T-cells, Echinacea, Siberian, Ginseng, Pau d'arco, Mushroom, Complex, Reishi, Shitake. http://www.inteme.com/iom/team/n-immune.html
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Lersch, C., M. Zeuner, A. Bauer, K. Siebenrock, R. Hart, F. Wagner, U. Fink, H. Dancygier, and M. Classen. 1990. Stimulation of the immune response in outpatients with hepatocellular carcinomas by low doses of cyclophosphamide (LDCY), Echinacea purpurea extracts (echinacin) and thymostimulin. Arch Geschwulstforsch 60:379-383.
Mengs, U., C.B. Clare, and J.A. Poiley. 1991. Toxicity of Echinacea purpurea: Acute, subacute, and genotoxicity studies. Arzneim-Forsch 41: 1076-1081.
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cell cultures of Echinacea purpurea enhance the resistance of
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