Echinacea Echinacea purpurea (L.) Moench Text by Armando González Stuart, Ph.D., 2005 Botanical family: Asteraceae. Common names: Of the 9 species contained within the genus Echinacea, 3 are currently employed medicinally: Echinacea purpurea or purple coneflower, E. pallida or pale coneflower and E. angustifolia or narrow-leaved Echinacea (Islam and Carter, 2005; Barrett, 2004; Sperber et al., 2004; Wichtl, 2004; Fugh-Berman, 2003; Hoffmann, 2003; Mahady et al., 2001). Medicinal parts: The roots, flowers or the whole plant, depending on the species used (McKenna et al., 2002; Bauer, 1998). History Echinacea is one of the best selling medicinal plants on the natural supplement market in the United States (Bauer R, Woelkart, 2005; Castleman, 2001; Karch, 1999; Tyler, 1998). Native to the central portion of the United States, Echinacea was used by many Native American tribes for a variety of ailments, ranging from respiratory infections to snakebite (Foster and Tyler, 2000; Davis and Cupp, 2000). This plant was employed extensively by the eclectic physicians in the U. S. during the nineteenth century and was officially included in the United States National Formulary until 1950 (Mahady et al., 2001; Presser, 2000). Although it is originally from the North American continent, most of the recent research on its medicinal properties has been carried out in Europe (Tyler, 1998). 1 Echinacea has been used by various Native American tribes to treat minor wounds, skin infections, as well as against arthropod bites, snakebite, and stings (Bartram, 2001; Mahady et al., 2001; Hansel et al., 2001; Brown, 2001). Some Echinacea preparations have been adulterated with another closely related plant, Parthenium integrifolium, commonly known as “Missouri snakeroot” or “prairie dock”. To confound the situation further, Echinacea is also known by the vernacular name “Missouri snakeroot” (McKenna et al., 2002). It is quite possible that much of the early research on Echinacea’s medicinal properties was done on Parthenium instead of Echinacea, due to mistaken identity (McKenna et al., 2002; Bascom, 2002; Brown, 2001;Bauer, 1998; Duke et al., 2002). Products containing Echinacea include lollipops, tablets, extracts, capsules, tinctures, teas and lozenges. Injectable (parenteral) preparations have been banned in some European countries and were never authorized in the United States (Fetrow and Avila, 2004; Wichtl, 2004) Active principles • Although the 3 medicinal species belong to the same genus, they do not have exactly the same curative properties or active principles (Bauer and Woelkart, 2005; Wichtl, 2004; Blumenthal, 2003; McKenna et al., 2002; Bauer, 1998). • The roots of E. pallida and E. angustifolia contain caffeoyl derivatives such as echinacoside, which are absent in E. purpurea (Mahady et al., 2001; Bartram, 2001). Echinacoside has both antibacterial and antiviral effects in vitro (Bauer R, Woelkart, 2005; Mahady et al., 2001). • The sesquiterpene lactone esters originally reported for E. purpurea, have subsequently been attributed to another species within the same botanical family: Parthenium integrifolium (Sandberg and Corrigan, 2002). • In Europe, research done on the species Echinacea purpurea before 1990 may have been done on another species, E. pallida, due to mistaken identification of the plant (Wichtl, 2004; Weiss and Fintelmann, 2001; Bauer, 1998). • There are conflicting opinions as to the similarity of the medicinal properties between Echinacea and its common adulterant, Parthenium. Some authors suggest Parthenium has no medicinal activity (Davis and Cupp 2000), while others suggest the curative properties of this plant are very similar to those of Echinacea (Duke et al., 2002). • Caffeic acid derivatives, such as chicoric acid and chlorogenic acid, which purportedly confer immunostimulant activity to the plant by increasing cellular phagocytosis activity. (Kraft and Hobbs, 2004; Wichtl, 2004; Hoffmann, 2003; Mahady et al., 2001; Kuhn and Winston, 2000; Bauer, 1998), although the exact confirmation of the active principles remains unknown (Weiss and Fintelmann, 2001; Foster and Tyler, 2000). 2 • Chicoric acid is a major component in E. purpurea, but is found only in small amounts in the other two medicinal species; E. pallida and E. angustifolia (Dewick, 2002). • Polyacetylenes including ketoalkynes and ketoalkenes may confer immunostimulating properties to the herb (Dewick, 2002; Kuhn and Winston, 2000). Applications in herbal therapy • Prevention and early-onset treatment of colds. • Sinusitis and upper respiratory infections (URI’s). • Inflammation of the middle ear (otitis media). • Infections of the lower urinary tract. • Coadjuvant therapy for recurring vaginal yeast (Candida albicans) infections. • Externally, Echinacea preparations are employed against skin infections and carbuncles, applied as an ointment (Barrett, 2004; Wichtl, 2004; Blumenthal, 2003; Hoffmann, 2003; Bartram, 2002; Ottariano, 1999; Blumenthal, 1998). • The wound healing properties of Echinacea are reported to be due to inhibition of the bacterial enzyme, hyaluronidase, which enables these organisms to spread within the wound. Caffeic acid derivatives such as chicoric acid, cynarin, cafteric acid and chlorogenic acid apparently are responsible for the plant’s anti-hyaluronidase activity. The other medicinal effect is by stimulation of fibroblasts to produce granulation tissue (Davis and Cupp, 2000; Bauer, 1998). • Echinacea’s anti-inflammatory action seems to be due to its high molecular weight polysaccharide constituents (Bauer R, Woelkart, 2005; Hoffmann, 2003; Tyler 1998; Tragni et al., 1988). • Some studies undertaken in Europe and the United States report that Echinacea may be effective for the prevention and treatment of colds (Barnes et al. 2002; Weiss and Fintelmann 2000; Blumenthal et al. 1998;), although in some studies, products contained not only Echinacea, but other plants as well ( Kim et al., 2002; McKenna et al., 2002; Lindenmuth and Lindenmuth, 2000; Blumenthal et al., 2000), making interpretations of the results difficult to accredit solely to Echinacea (Rotblatt and Ziment, 2002). • A recent review of clinical trials employing Echinacea for the treatment of the common cold concluded that the therapeutic effectiveness of this plant has not been established (Caruso and Gwaltney, 2005). 3 Clinical Studies with Echinacea • According to Bascom (2002), there have been more than 350 studies related to the efficacy and safety of different species of Echinacea. Most of these trials have been undertaken in Europe (Tyler, 1998). Unfortunately the methodological quality of some of these trials has not been adequate, since not all studies have been randomized or have not included the double-blind placebo procedure (Fetrow and Avila, 2004; Sperber et al., 2004; Mahady et al., 2001). • Another problem encountered in some of the trials is the great variability in the content of the purported active principles among the different brands (in some cases, even within the same brand) of Echinacea products sold as over the counter (OTC) medications. Such variation is not only present among different brands, but apparently also among products of the same brand (Sperber, et al., 2004; Davis and Cupp, 2000; Bauer, 1998). • In a systematic review of 26 controlled clinical trials which employed Echinacea as an immunomodulator, Melchart et al. (1994), concluded that most of the studies had a low score in relation to methodology and that insufficient evidence exists as to recommend individual Echinacea preparations for individual use. The authors stated the need for further well controlled studies to determine the clinical effectiveness of the plant drug. • Another 16 trials consisting of 8 prevention trials and 8 trials on treatment of upper respiratory tract infections with a total of 3396 participants were reviewed. The selection criteria consisted of randomized and quasi-randomized trials comparing preparations containing an extract of Echinacea compared with a placebo, no treatment, or alternate treatment for common colds. The great range of variation in the different preparations investigated and the lack of consistency in methodological quality shown in the trials did not meet the criteria for a quantitative meta-analysis. In general, the results suggested that some Echinacea preparations may be better than placebo for the treatment of some respiratory infections (Melchart et al., 2000). • Grimm and Muller (1999) undertook an experiment with a total of 109 patients with a history of more than 3 colds or respiratory infections in the preceding year. In a double-blind study, the test subjects were randomly assigned to receive 4 mL fluid extract of Echinacea purpurea or 4 mL placebo-juice two times a day. The incidence and severity of colds and respiratory infections were determined during 8 weeks of follow-up, based on patient reported symptoms along with the results from a physical examination. No significant differences were found between treatment groups in the number of infections in each category of severity. The authors concluded that treatment with fluid extract of Echinacea purpurea did not significantly decrease the incidence, duration or severity of respiratory infections and colds compared to placebo. • In a randomized, double-blind, placebo-controlled community-based trial set at an American university, Barret et al. (2002), evaluated the efficacy of dried, encapsulated, whole plant Echinacea as an early treatment for the common cold on a total of 148 university students afflicted with common colds of recent onset. After 10 days of treatment, the researchers 4 concluded that unrefined Echinacea did not show any detectable benefit or harm, compared with placebo in the students who suffered from the common cold. • The most reliable data come from research trials testing E. purpurea extracts for the treatment for acute upper respiratory infections or URI’s (Mahady et al., 2001). Although test results suggest a modest benefit, the trials have been generally limited both in size and in methodological quality. In conclusion, although there is a great deal of moderately good-quality scientific data regarding the effectiveness of E. purpurea, in treating illness or in enhancing the human immune response, this has not yet been conclusively proven (Bauer and Woelkart, 2005; Islam and Carter, 2005; Barret, 2003; Block and Mead, 2003). • Echinacea may also have health implications in veterinary medicine. A double-blind, placebocontrolled, cross-over trial investigated the effects of standardized Echinacea extract on horses. Eight animals were supplemented with Echinacea or placebo for 42 days, and their response to supplements recorded. Horses treated with Echinacea increased phagocytic ability of isolated neutrophils, increased peripheral lymphocyte counts and appeared to stimulate neutrophil migration from peripheral circulation into the tissues. The Echinacea product used in the study also increased the size and concentration of peripheral red blood cells, as well as the concentration of hemoglobin and packed cell volume. The results showed that Echinacea effectively stimulated equine immunocompetence. Additionally, the Echinacea extract acted as a hematinic agent (it improved the quality of blood by increasing hemoglobin levels and the number of erythrocytes).These effects are considered to improve parameters of exercise physiology and performance in equines (O’Neill et al., 2002). Table 1. Selected Clinical Trials Employing Echinacea . Reference HeinenKammerer et al., 2005 Turner et al., 2005 Plant Part / Herbal Product Purpose of study To evaluate whether treatment of chronic recurrent respiratory disease with a commercial Echinacea product was more effective compared to therapy Echinacin® commercial without an herbal product immunomodulator To asses the effect of chemically defined extracts from E. Chemically defined angustifolia roots on extracts from subjects Echinacea angustifolia experimentally roots infected with 5 Number of subjects Results 995 Effective 437 Not effective rhinovirus type 39 To evaluate the effectiveness and safety of a composite herbal product in the Herbal preparation prevention of (Chizukit) containing respiratory tract Cohen et al., echinacea, propolis and infections in children 2004 vitamin C aged 1-5 years To determine the efficacy of a standardized preparation of E. purpurea in reducing Freeze-dried pressed symptom severity and Yale and Liu, juice from the aerial duration of the 2004 parts of the plant common cold To evaluate the Echina Gard ability of Echinacea (Echinacin)® freezepurpurea to prevent dried pressed juice from infection with Sperber et al., the aerial parts of E. rhinovirus type 39 2004 (RV-39) purpurea To determine the effectiveness of E. purpurea in reducing Freeze-dried pressed the severity and / or juice from the aerial duration of URI’s in Taylor et al., parts of E. purpurea children 2-11 years 2003 mixed into a syrup old Lindenmuth Evaluation of and Echinacea Plus® tea, Echinacea for Lindenmuth, made from dried herb decreasing duration 2000 and root of cold symptoms Turner et al., N/A Prevention of the 2000 common cold Brinkeborn et Echinaforce® (German Treatment of al., 1999 product), symptoms of the fresh extracts common cold Grimm et al., Fluid extract Prevention of the 1999 common cold Brinkeborn et Extracts of aerial Treatment and al .,1998 parts and root reduction symptoms of colds Melchart et al., Extracts of root Prevention of the 1998 common cold Dorn et al., Root extract Treatment and 1997 duration of colds 6 430 Effective 128 Not effective 46 Not effective 407 Not effective 95 117 Effective Not effective 246 Effective 109 Not effective 199 Effective 302 Not effective 160 Effective Hoheisel et al., 1997 Braunig et al., 1993 Braunig et al., 1992 Schoneberger et al., 1992 Pressed juice Root extract Root extract Pressed juice Treatment and duration of colds Treatment and duration of colds Treatment of the common cold Prevention of the common cold 120 180 Effective Effective 160 Effective 108 Not effective Additional information about clinical trials and the products tested is available in the following publications: Coates et al. Encyclopedia of Dietary Supplements. New York: Marcel Dekker; 2005; Ulbricht C, Basch E. Natural Standard: Herb and Supplement Reference. New York: Elsevier; 2005; Barrett, M. Handbook of Clinically Tested Herbal Remedies, 2 vols.. New York: Haworth Herbal Press; 2004; Miller SC. Echinacea: The Genus Echinacea. Boca Raton, FL.: CRC Press; 2004; Blumenthal, M. ABC’s Clinical Guide to Herbs. New York: Thieme; 2003; Bratman S, Girman A. Handbook of Herbal Supplements and Their Therapeutic Uses. St. Lous: Mosby; 2003; European Scientific Cooperative On Phytotherapy (ESCOP) Monographs. New York: Thieme; 2003; Bascom A. Incorporating Herbal Medicine into Clinical Practice. Philadelphia: F. A. Davis; 2002; Yarnell, E. et al., Clinical Botanical Medicine. New York: Mary Ann Liebert; 2003; Cassileth B, Lucarelli C. HerbDrug Interactions in Oncology. London: BC Decker; 2003; McKenna et al., Botanical Medicines. New York: Haworth Herbal Press; 2002; Rotblatt M, Ziment I. Evidence-Based Herbal Medicine. Philadelphia: Hanley and Belfus; 2002; Mahady et al., Botanical Dietary Supplements. The Netherlands: Swets and Zeitlinger; 2001; Cupp M. Toxicology and Clinical Pharmacology of Herbal Products. Totowa, New Jersey: Humana Press; 2000. Safety/Precautions • Although toxicological information about Echinacea based products is scarce (Davis and Cupp, 2000; Bauer, 1998), the plant is considered to be safe when taken internally (Block and Mead, 2003; Meletis, 2002; Mahady et al., 2001; Brinker 2000; Presser, 2000; Libster, 2002; Rotblatt and Ziment, 2002). • Single oral or intravenous doses of the expressed juice of Echinacea purpurea proved to be virtually non-toxic to rats and mice. Tests for mutagenicity carried out in microorganisms and mammalian cells in vitro and in mice all also gave negative results (Mengs et al., 1991). • Cross sensitivity reactions between Echinacea and other members of the daisy or sunflower family, such as ragweed or chrysanthemum are possible (Mahady et al., 2001; Davis and Cupp, 2000). • Some authors suggest that the immune system of people taking Echinacea products for a long time may be over stimulated and later suppressed (Blumenthal, 2000 ;Weiss and Fintelmann, 2000), although no experimental data exist to confirm this (Bascom, 2002; Mahady et al., 2001). 7 • Preliminary testing undertaken in pregnant women did not reveal any teratogenic effects. A total of 206 women were enrolled in this prospective controlled study, after having used Echinacea products during pregnancy. Of these, 112 women used the herb in the first trimester of gestation. The authors concluded that there were no significant statistical differences between the women taking Echinacea and the control group for any of the principal endpoints analyzed (Gallo et al., 1998; Gallo and Koren, 2001). • Echinacea should not be taken during pregnancy. The plant’s effects upon lactation have not been evaluated (Huntley et al., 2005; Fetrow and Avila , 2004; Sarkar and Koren, 2004; Barnes et al., 2002; Meletis, 2002). • Patients allergic to ragweed or other members of the Composite or Daisy family, such as Marigold, Arnica or Chamomile, may show cross sensitization to Echinacea products (Mullins, 1998). Injectable preparations were available in Europe, but have been banned in some countries, due to the potential risk of anaphylactic shock in sensitive individuals (Wichtl, 2004; Vanaclocha and Cañigueral, 2003; McKenna et al., 2002). • It has been suggested that Echinacea preparations could be toxic to the liver, due to the presence of pyrrolizidine alkaloids in the plant, but this is not accurate, since Echinacea lacks the 1,2 saturated necine ring associated with hepatoxicity of various pyrrolizidine alkaloids (Miller, 1999). • The unsaturated type pyrrolizidine alkaloids which are potentially hepatotoxic and carcinogenic are not present in Echinacea (Blumenthal, 2003; Barnes et al., 2002; Duke et al., 2002; McKenna et al., 2002; Mahady et al., 2001). • The German Commission E has contraindicated the use of Echinacea in patients suffering from HIV infection or autoimmune diseases (Hoffmann, 2003; Schulz et al. 2001; Blumenthal et al. 1998), but some researchers believe that the use of Echinacea in AIDS patients may be useful and that the contraindications mentioned in the Commission’s monograph on Echinacea are either theoretical or poorly substantiated (Blumenthal, 2003; Mills and Bone, 2000; Bone, 1997-1998). • Although the Commission E monograph on Echinacea mentions that continuous treatment with Echinacea products should not exceed 8 weeks (Blumenthal, 1998; Schulz et al., 2001) this statement is not related to toxicity, but to the possibility that the plant’s effectiveness may wane with time, rendering it less effective (Blumenthal, 2003). • There is currently no clinical evidence that Echinacea use is effective in small children, especially under 12. The use of Echinacea products in infants should be undertaken only under the direction of a health professional (Hrastinger et al., 2005; Barret, 2004; Taylor et al., 2003). • There is one documented case of recurrent erythema nodosum possibly associated with Echinacea use (Soon and Crawford, 2001). 8 Herb/Drug interactions • The possible herb-drug interactions involving Echinacea are for the most part unknown. In vitro test results have reported that Echinacea could alter the effectiveness or metabolism of drugs that are substrates of various CYP 3ª4 isozymes (Gorski et al., 2004; Brinker, 2001; Mahady et al., 2001; Herr, 2002). • Echinacea preparations may theoretically reduce the efficacy of immunosuppressant medications, such as cyclosporine and tacrolimus, for example (Cassileth and Lucarelli, 2003). Literature cited Barnes J, Anderson L, Phillipson D. Herbal Medicines 2nd Edition. London: Pharmaceutical Press; 2002. Barrett M. 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