Echinacea (E. purpurea, pallida and angustifolia) is a group of medical herbs in the Asteraceae family used to treat common cold and infections. Because of its purple and white flower’s beauty, this plant is often used in gardens for decorative purposes, although it is also widely appreciated for its medical properties. Echinacea is an immunostimulant that activates the immune system and is thus used to treat or prevent seasonal influenza (flu), skin infections, microbial diseases other minor ailments. E. purpurea has been used in folk medicine for centuries, especially by Native American Plain Tribes who used it to treat wounds and serpent bites since it may inhibit enzymes in the hyaluronidases family. According to tradition, tribesmen learned about this herb’s healing properties by observing the wapiti elks who consumed it when they were sick or wounded.
Echinacea species are perennial, herbaceous plants that look like daisies, with large heads of composite flowers whose petals point downwards. The central disk is spiny and full of yellow pollen (white in E. pallida), and gives the name to the plant itself (“echinos” is the ancient Greek word for hedgehog). Also known as purple coneflowers, these herbs only grow in central and eastern North America. It prefers inland wooded areas and dry prairies and sunny climates.
Medical Properties and Chemical Constituents
The principal chemicals constituents of echinacea are echinacoside, essential oils, caffeic acid, caftaric acid, glycoproteins, and polysaccharides. The herb is often used to treat upper respiratory infections and chronic recurrent urinary infections due to its generalized stimulant activity on the immune system that helps fight off microbes. Topical preparations are also effective to treat many local skin conditions. Echinacoside’s weak antibiotic action is strengthened by the antimicrobial properties of the plant’s terpene-rich essential oil. Other chemical compounds are also active against leishmania and brucellosis trypanosome protozoans.
The various active substances are extracted from the black and thick roots, the leaves and the flowers. Their concentration, however, varies widely among the various commercial products available since different parts of the plant are used in different proportions, and the various sub-species are also often mixed. For this reason, the many scientific trials that tried to determine echinacea’s clinical activity showed significantly different results. Nonetheless, this herb’s anti-disease effects have been confirmed by many international agencies such as the European Medicines Agency (EMA).
Other unconfirmed researches and anecdotal studies suggest that echinacea may also possess a weak anti-inflammatory activity. Coupled with the ability to inhibit the hyaluronidases, this plant is also employed in cosmetic products as an anti-aging agent. The theory is that coneflowers extracts may strengthen the structure of dermal connective tissue by increasing the concentration of hyaluronic acid inside it. Its antimicrobial and anti-inflammatory activity may also contribute to a generalized anti-wrinkle activity.
Toxicity and Contraindications
Due to its immunostimulant activity, echinacea is contraindicated in patients taking immunosuppressive drugs, subjects that received an organ transplant, and in cases of autoimmune conditions, progressive systemic disorders, and diseases of the white blood cell system. There is a possible risk of severe hypersensitivity
reactions in allergic subjects. Some studies found evidence of possible hepatotoxicity if the herb is taken for a long period of time (10 days or more), and its use is thus not recommended in patients with compromised liver function. Coneflower may interact with several drugs, including paracetamol and other common over-the-counter medications used to treat cold. Since it induces cytochrome P450 (CYP3A) this herb may alter the metabolism and pharmacokinetics of many medications such as antidepressants, antihypertensives, proton pump inhibitors, and anticoagulants. Although echinacea it is usually safe for pediatric uses, European authorities recommended against its use in children under the age of 12. Since no convincing evidence about its safety during gestation is yet available, pregnant women should not take products containing this plant extracts. Due to its numerous contraindications and possible drug interactions, patients should always consult their pharmacist or doctor before using echinacea.
Articolo written by Dr. Butticè Claudio, PharmD.
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