Echinacea – a useful herb for allergies

The best known use for the root of Echinacea (also known as Purple Coneflower), is the prevention or treatment of upper respiratory tract infections, such as influenza and the common cold, and its pharmacological activity is often simplified down to being regarded as an ‘immuno-stimulant’.

A close look at the traditional applications for Echinacea however, suggest its most prominent uses were to reduce inflammation. The traditional uses by North America Indians and early European settlers, included inflammatory conditions such as snake bites, sore throats, swollen gums and abscesses, and other conditions where a high level of localised or systemic inflammation is characteristic. Much of Echinacea’s established pharmacology therefore also relates to an anti-inflammatory mode of action, with tongue-tingling alkylamides being the key active phytochemicals (1, 2).

Inflammation is also a major component of many allergic and autoimmune conditions, including asthma, hay fever or systemic lupus erythematosus. Anti-inflammatory drugs such as prednisone, beclomethasone and flumethasone are frequently prescribed to reduce the symptoms of these. The concept of Echinacea being used for such conditions can be hard to grasp, particularly when influential texts such as the German ‘The Complete Commission E Monographs’, the European Pharmacopoeia and websites presenting information on medicinal herbs, make statements such as:

“Because of its immunostimulating activity, Echinacea must not be used in cases of progressive systemic disorders (tuberculosis, sarcoidosis), autoimmune diseases (e.g.: collagenoses, multiple sclerosis), immunodeficiencies (e.g.: HIV infection; AIDS), immunosuppression (e.g.: oncological cytostatic therapy; history of organ or bone marrow transplant), diseases of the white blood cell system (e.g.: agranulocytosis, leukemias) and allergic diathesis (e.g.: urticaria, atopic dermatitis, asthma).

Despite such statements, there is in fact no substantiated evidence of Echinaceas absolute contraindication in any of the above immunological or autoimmune conditions, making this precautionary statement a potential theoretical, rather than clinically proven one.

Something else that European regulators are overly sensitive about is the likelihood of Echinacea triggering allergic reactions, to the point of advising against its use in children under the age of 12. The background to this however, is likely attributable to the greater prevalence in Europe of products containing either the whole plant or flowering tops of Echinacea, rather than just the root. Using just the root is more often seen in Australia, New Zealand and North America. Products made using flowering Echinacea tops contain higher pollen levels, and are therefore more likely to be associated with allergic reactions in atopic subjects, as seems to have been the case in Europe(3).

Further insight into whether Echinacea is or isn’t safe to use in autoimmune conditions, was provided by a recent American study which investigated its effects on mast cells(4).  Mast cells are a type of white blood cell and known to be important mediators of allergic and inflammatory responses. Upon exposure to an allergen and release of immunoglobulin E (IgE) antibodies, an influx of calcium occurs resulting in mast cell degranulation and the release of inflammatory mediators such as histamine, leukotrienes, and other pro-inflammatory cytokines. These actively contribute to allergic reactions and the subsequent inflammatory response, including those seen in asthma and allergic rhinitis (hay fever). The main mechanism of drugs such as sodium cromoglycate, used as an inhalation for hay fever and asthma, is to reduce mast cell release of histamine and other inflammatory mediators.

Effects of an ethanolic extract of Echinacea purpurea root were evaluated on mast cell degranulation, calcium influx, cytokine and lipid mediator production, using both bone marrow derived mast cells and a rat basophilic leukemia mast cell lines. As well as the crude Echinacea root extract, a purified alkylamide (dodeca-2E,4E-dienoic acid isobutylamide), and fractions containing both low and high alkylamide levels, were also tested for effects on mast cell function.

The Echinacea extract and isolated dodeca-2E,4E-dienoic acid isobutylamide, inhibited degranulation from both mast cell types after treatment with a calcium ionophore, as well as after stimulation with IgE. Histamine release from the rat basophilic leukaemia mast cell lines, was reduced by 47%, and that of TNF-alpha and prostaglandin E2 (PGE2), but by a lesser degree. Inhibition of calcium influx by Echinacea and its alkylamides, was implicated as a mechanism of action, and as similar actions were shown also on non-mast cells, other possible pharmacological actions of benefit in both inflammatory and autoimmune conditions, are likely.

Inhibition of mast cell degranulation and calcium influx was observed by Echinacea purpurea extracts and Echinacea fractions with high alkylamide content, but not by fractions with little to no detectable alkylamide levels. This implicates alkylamides in the anti-allergic actions of Echinacea purpurea root extract, and adds to the large existing body of evidence that they contribute significantly to the overall immunomodulatory and anti-inflammatory actions of this plant.

The combined effects of Echinacea purpurea on mast cell activation, considered together with research showing it reduces the release of inflammatory cytokines from macrophages, suggests the possible application of high alkylamide-containing Echinacea purpurea extracts for limiting inflammation associated with allergic responses, in addition to that associated with infections.

Further evidence of Echinacea’s anti-allergic effects was provided recently from results of a study by Hungarian and German researchers, who found an alkylamide-rich Echinacea extract to exert strong anti-inflammatory effects and help restore the epidermal lipid barrier, in patients with atopic (allergic) eczema. Topical application of an Echinacea cream, reduced both pruritis (itchiness) and redness in an 85 day clinical trial involving patients with atopic eczema, particularly from days 57 to 85(5).

Refs:

  1. Rasmussen PL, Phytonews 14 , Evaluation of anti-inflammatory effects of Echinacea purpurea and Hypericum perforatum, ISSN 1175-0251, published by Phytomed Medicinal Herbs Ltd, Auckland, New Zealand, Dec 2002
  2. Rasmussen PL, Phytonews 24 , Effects of Echinacea on virus-induced respiratory cytokines, ISSN 1175-0251, published by Phytomed Medicinal Herbs Ltd, Auckland, New Zealand, Feb 2006
  3. Rasmussen PL, Phytonews 38 , Safety of Echinacea in Children, ISSN 1175-0251, published by Phytomed Medicinal Herbs Ltd, Auckland, New Zealand, Dec 2012
  4. Gulledge TV, Mast cell degranulation and calcium influx are inhibited by an Echinacea purpurea extract and the alkylamide dodeca-2E,4E-dienoic acid isobutylamide. J Ethnopharmacol. 2018 Feb 15;212:166-174.
  5. Oláh A et al, Echinacea purpurea-derived alkylamides exhibit potent anti-inflammatory effects and alleviate clinical symptoms of atopic eczema. J Dermatol Sci. 2017 Oct;88(1):67-77.

 

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