Echinacea purpurea

 

Echinacea purpurea 

Synonyms

No documentation 

Vernacular Name

Eastern purple coneflower, common purple coneflower, snakeroot, scurvy root, comb flower, and hedge hog.[1],[2],[3]

Description

Echinacea purpurea is one of many species of Echinacea and is characterized by the purple color of its flowers and oval-shaped leaves. E. purpurea belongs to the Asteraceae family and is found actively growing during the spring and summer months with blooms beginning to appear during the early summer. E. purpurea and angustifolia are often referred to as ‘Echinacea’ though each species has its own characteristics.

Comprised of a single stem, green foliage, purple flowers and black fruit/seeds, E. purpurea is easily recognizable and one of the most popular botanicals used in medicinal preparations worldwide. E. purpurea has been employed as an immunomodulatory agent due to its ability to enhance the body’s natural defenses against pathogens. As a result, E. purpurea is marketed commercially for the treatment of viral infections including, but not limited to, the common cold, influenza, herpes, etc.

Origin / Habitat

Use of echinacea originated with North American Native Americans; however, there are reports its early use in Europe. It grows in Mid-West to Southern United States. Although this plant can thrive in basic, acidic, or neutral soils, it cannot grow in the shade; it needs complete sun. Echinacea can tolerate drought very well, as well as frost. It is common to see Echinacea growing in prairies and along roadsides

Chemical Constituents

Caffeic acid derivatives (e.g., cichoric acid)

Alkylamides (e.g. dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamides)

Polysaccharides (e.g. acidic arabinogalactan, acidic arabinorhamno-galactans)

Polyynes (e.g. trideca-1,11-dien-3,5,7,9,-tetraine)

Sesquiterpenes (e.g. germacrene D)

Glycoproteins (arabinogalactan-proteins)[4],[5],[6],[7],[8]

Plant Part Used

The medicinal preparations are made from the root and aerial (herb) portions; portion succus (fresh plant juice) is also utilized. E. purpurea preparations may be found in the form of teas, tablets, capsules, pressed juice and powders.

Medicinal Use

General

Prophylaxis and treatment of upper respiratory infections (URIs) and additional infections of varying etiologies.[9],[10],[11],[12]

Prophylaxis of infection and enhanced wound healing by external application to wounds and treatment of inflammatory conditions.[13],[14]

 

Most Frequently Reported Uses 

Prophylaxis and treatment of upper respiratory infections (URIs) and additional infections of varying etiologies.[9],[10],[11],[12]

Dosage

Dosage Range 

250mg (standardized extract) taken 4 times a day during flu season. Some clinicians recommend a dosing cycle. For example, use Echinacea for 3 weeks, refrain from use for 1 week and begin again. Alternatively, use for 8 weeks followed by 1 week off.

Most Common Dosage 

Acute use: 500 mg (standardized extract) taken 3 times a day for the first day; from the second day onward, 250 mg taken 4 times a day. For prevention: 250 mg (standardized extract) taken 2 times a day; a dosing cycle may be employed as discussed above. For E. purpurea liquid (succus), the recommended dose is 60 drops, 3 times a day with food for the first day; from the second day onward, 40 drops, 3 times a day with food for up to 10 days.

 

Standardization Dosage 

No documentation

Pharmacology

Pre-clinical

Ethnomedicine has long employed E. purpurea in the treatment of immune-related illnesses. E. purpurea and its constituents have been shown to possess immunostimulatory activity in laboratory investigations. These investigations have utilized in vitro methods to demonstrate that administration of E. purpurea preparations, and/or its constituents, produces activation of human and murine macrophages, increased T-cell proliferation, enhanced viability of human peripheral blood mononuclear cells, increased macrophage secretion of tumor necrosis factor-alpha and several interleukins including interleukin-1 and interleukin-6, and enhanced cytotoxicity.[4],[10],[15],[16],[17],[18] These studies illustrate the nonspecific, cell-mediated immune response attributable to administration or consumption of E. purpurea preparations and the potential for increased pathogenic resistance conferred upon its users. The immunostimulatory effects of E. purpurea preparations appear to be dose-dependent, as evidenced by quantitative assays for E. purpurea-induced increases in tumor necrosis factor-alpha, nitric oxide and human peripheral blood mononuclear cell viability.[18] E. purpurea herb processed through simulated digestion dose-dependently induced secretion of macrophage-derived tumor necrosis factor-alpha, nitric oxide, interleukin-1alpha, interleukin-1beta and interleukin-6.[18] E. purpurea preparations that failed to stimulate tumor necrosis factor-alpha production also failed to enhance human peripheral blood mononuclear cell viability.[18] Thereby, it appears that the ability of E. purpurea to alter the activities of the immune system may be due, at least in part, to the modulatory effects E. purpurea exhibits on cytokines.

The in vivo studies in mice demonstrate that consumption of E. purpurea root extract increased the number of natural-killer cells and monocytes within bone marrow and spleen, when compared to control animals; the increases were observed as early as approximately 1 week after commencement of treatment.[3],[19] Furthermore, in vivo administration of purified polysaccharides from E. purpurea produced proliferation of phagocytes within bone marrow and spleen of mice whilst also inducing migration of granulocytes to the peripheral blood.[16] These immunostimulatory activities may explain the immunoprotection against systemic infection by Listeria monocytogenes and Candida albicans observed in subsequent experiments.[16] Studies employing cyclophosphamide or cyclosporine A-induced immunosuppressed mice show that treatment with polysaccharides isolated from E. purpurea restores resistance to infection by Listeria monocytogenes and Candida albicans.[4] Extract of E. purpurea and two of its alkylamide constituents have been shown to dose-dependently inhibit interleukin-2 production through suppression of the ability of activated Jurkat T cells to produce interleukin-2; these actions may influence the infection response and amelioration of infectious symptoms attributed to E. purpurea use.[20] Despite cellular evidence of immunostimulation in laboratory studies, the precise pathways by which E. purpurea may confer resistance against infectious diseases remain elusive and it appears that the precise constituents comprising E. purpurea preparations impact the pharmacological effects associated with Echinacea use.

A plethora of research has focused on the constituents of Echinacea to elucidate the mechanisms of action by which Echinacea produces its effects. The alkylamides, detectable in human blood samples in relevant concentrations following oral E. purpurea administration, are structurally similar to anandamide, an endogenous agonist for cannabinoid receptors.[5],[21] In vitro, alkylamides have been shown to bind to cannabinoid type 2 (CB2) receptors with high affinity and to subsequently increase total intracellular calcium and activate mitogen-activated kinases, presumably through a g-protein coupled mechanism; the alkylamide-induced increased intracellular calcium is inhibited in the presence of a CB2 antagonist.[5],[21] The expression of CB2 receptors is abundant within immune and inflammatory-competent cells; hence, the interactions of constituents of E. purpurea with this receptor population and the subsequent cascades initiated may modulate the inflammatory and immunological effects associated with Echinacea use.[21],[22],[23] Furthermore, it appears that the alkylamides may influence the inflammatory and immunological effects of E. purpurea through upregulation of the expression of constitutive interleukin-6 in human whole blood and inhibition of lipopolysaccharide-induced secretion of tumor necrosis factor-alpha and interleukin-1beta but in a manner that appears to be independent of the CB2 receptor.[21] Several alkylamides isolated from E. purpurea have been shown to inhibit cyclooxygenase-I and cyclooxygenase-II enzymes in vitro and may modulate inflammation and the perception of pain through these actions.[14] In vivo experiments in rats have shown oral gavage of alkylamides isolated and purified from E. purpurea to increase the phagocytic activity of alveolar macrophages.[24]

Acidic arabinogalactan, another constituent of Echinacea, has been shown to increase the production of immunological mediators (including tumor necrosis factor-alpha, interferon-beta2, and interleukin-1) through its actions on macrophages and to produce a slight increase in T-cell proliferation.[16] Arabinogalactan has exhibited cytotoxicity against tumor cells in laboratory studies and antiparasitic activity against parasites responsible for Leishmaniasis.[16] Glycoproteins isolated and purified from the pressed juice of E. purpurea, the arabinogalactan-proteins, have shown only weak stimulation of interleukin-6 and nitrite production in alveolar mouse macrophage cultures.[8],[25] Extracts of E. purpurea have been shown to have phototoxic antimicrobial activity against clinically relevant pathogenic fungi and E. purpurea has shown antioxidant activity in assays assessing the scavenging of hydroxyl radical, 1,1-diphenyl-2-picrylhydrazyl radical and ABTS radical.[7],[26] Taken together, the biological activities of E. purpurea, and its constituents, have therapeutic implications in the treatment of infectious disease, inflammatory conditions and tumors.

Clinical

Reviews of available literature detail the clear controversy regarding the clinical effectiveness of Echinacea; several studies have shown Echinacea to be effective in the prophylaxis and/or attenuation of illnesses such as the common cold, while several other studies have reported no clinical benefits.[12],[27],[28],[29] Preclinical studies provide support for the immunostimulatory effects associated with Echinacea use; clinical trials assessing Echinacea preparations in the prophylaxis and treatment of upper respiratory infections have demonstrated favorable differences in the treatment versus control groups.[3],[9] The conflicting conclusions of these studies may be attributable to varying factors within the experimental designs, such as the use of different doses and/or preparations of Echinacea, different animal models employed, and/or differing parameters measured to evaluate outcome in patients. The discrepancy in findings may also be due to failure of Echinacea products to meet recognized pharmaceutical quality standards.[9] The immunostimulatory activity of Echinacea preparations has been found to vary significantly by preparation and even raw material obtained from the same supplier varied greatly by lot when examined for immunostimulatory activity.[18] This occurrence may explain why some studies have shown immunostimulatory activity to be specific to E. purpurea herb and root powder preparations (when compared to extracts or fresh pressed juice) whilst others have demonstrated that the extracts display immunostimulatory activity (when compared to whole herb preparations).[18],[30]

Interaction and Depletions

Interaction with other Herbs

No documentation

Interaction with Drugs

Agents with potential or established hepatotoxicity (e.g. alcohol, methotrexate

acetaminophen/paracetamol, naltrexone, phenothiazines, black cohosh etc.)

Immunosuppressive agents (e.g. corticosteroids, cyclosporine)

Non-steroidal anti-inflammatory agents (e.g. aspirin, ibuprofen)

Chemotherapeutic agents

Interferon preparations

Antimicrobial agents

Antiplatelet agents

Anticoagulant agents

Agents with antioxidant activity

Precautions and Contraindications

Side effects

Patients possessing allergies to members of the Asteraceae family (e.g. sunflower, safflower, ragweed, chamomile and mugwort) should use E. purpurea with caution due to an established cross-reactivity between members within this family.  Allergic reactions have been documented in individuals with sensitivities to other members of the Asteraceae family following use of Echinacea; following exposure to Echinacea, allergic patients present with symptoms that range in severity from localized symptoms (rhinitis and/or urticaria) to acute asthma attack to generalized, life-threatening anaphylaxis.[9],[11],[35],[36]

Pregnancy

Patients planning to become pregnant, who are pregnant or breastfeeding should not use Echinacea supplements without first consulting their medical practitioner due to the lack of information concerning the use of supplements during pregnancy and lactation.[37]

Age limitation

Echinacea supplements should not be used in pediatric patients without first consulting a medical practitioner due to the insufficiency of scientific studies specific to the pediatric population.

Adverse reaction

The parental administration of Echinacea preparations has produced adverse reactions, including but not limited to urticaria, pyrexia and muscle weakness.[2]

Patients suffering from kidney, liver, immunosuppressive or chronic diseases should not begin any medicinal therapy without a consultation with their medical practitioner.

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References

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  3. Barrett B. Medicinal properties of Echinacea: a critical review. Phytomedicine. 2003;10:66-86.
  4. Steinmuller C, Roesler J, Grottrup E, Franke G, Wagner H, Lohmann-Matthes ML. Polysaccharides isolated from plant cell cultures of Echinacea purpurea enhance the resistance of immunosuppressed mice against systemic infections with Candida albicans and Listeria monocytogenes. International Journal of Immunopharmacology. 1993;15:605-614.
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