Purple coneflower (Echinacea purpurea) and Immune support: evidence and sources

Echinacea purpurea (Asteraceae) is a perennial medicinal herb with important immunostimulatory and anti-inflammatory properties, especially the alleviation of cold symptoms. The plant also attracted scientists' attention to assess other aspects of its beneficial effects. For instance, antianxiety, antidepression, cytotoxicity, and antimutagenicity as induced by the plant have been revealed in various studies. The findings of the clinical trials are controversial in terms of side effects. While some studies revealed the beneficial effects of the plant on the patients and no severe adverse effects, some others have reported serious side effects including abdominal pain, angioedema, dyspnea, nausea, pruritus, rash, erythema, and urticaria. Other biological activities of the plant such as antioxidant, antibacterial, antiviral, and larvicidal activities have been reported in previous experimental studies. Different classes of secondary metabolites of the plant such as alkamides, caffeic acid derivatives, polysaccharides, and glycoproteins are believed to be biologically and pharmacologically active. Actually, concurrent determination and single analysis of cichoric acid and alkamides have been successfully developed mainly by using high-performance liquid chromatography (HPLC) coupled with different detectors including UV spectrophotometric, coulometric electrochemical, and electrospray ionization mass spectrometric detectors. The results of the studies which were controversial revealed that in spite of major experiments successfully accomplished using E. purpurea, many questions remain unanswered and future investigations may aim for complete recognition of the plant's mechanism of action using new, complementary methods.

Echinacea purpurea (L.) Moench (EP)is a perennial herbaceous flowering plant, commonly known as purple coneflower and it belongs to the Asteraceae family. The Echinacea genus is originally from North America, in the United States, and its species are widely distributed throughout. There are nine different species of Echinacea, but only three of them are used as medicinal plants with wide therapeutic uses: Echinacea purpurea (L.) Moench, Echinacea pallida (Nutt.) Nutt. and Echinacea angustifolia DC. Several significant groups of bioactive compounds with pharmacological activities have been isolated from Echinacea species. Numerous beneficial effects have been demonstrated about these compounds. The immunomodulatory effect was initially demonstrated, but over time other effects have also been highlighted. The present review gives a comprehensive summary of the chemical constituents, bioactive compounds, biological effects and therapeutical uses of purple coneflower. Research shows that such a well-known and recognized species needs to be further studied to obtain efficient products with a guarantee of the safety.

This investigation examined the effects of Echinacea purpurea on mucosal immunity and the incidence and duration of upper respiratory tract infection (URTI). 32 subjects completed an exercise protocol known to affect mucosal immunity. Saliva was collected prior to and five minutes after completion of exercise testing. Subjects then took either a placebo (C) or Echinacea supplement (E) for 4 weeks and the testing procedure was repeated. Each time, s-IgA concentrations and saliva flow rate were measured and the secretion rate of s-IgA was calculated. In addition, standard logs indicating symptoms of URTI were completed throughout the study. Both groups demonstrated significant exercise induced reductions in s-IgA (C - 69 %; E - 43 %) and the secretion rate of s-IgA (C - 79 %; E - 53 %) at the beginning of the study (p < 0.05). Following the 4-week intervention, only the control group experienced the post intervention decrease in s-IgA (C - 45 %; E + 7 %) and the secretion rate of s-IgA (C - 45 %; E - 7 %). Further, while there was no significant difference in the number of URTI between groups, the reported duration was significantly different (C 8.6 days vs. E 3.4 days). The results suggest that Echinacea may attenuate the mucosal immune suppression known to occur with intense exercise and reduce the duration of URTI that subjects incur.

Extracts of Echinacea purpurea (EP, purple coneflower) have been used traditionally in North America for the treatment of various types of infections and wounds, and they have become very popular herbal medicines globally. Recent studies have revealed that certain standardized preparations contain potent and selective antiviral and antimicrobial activities. In addition, they display multiple immune-modulatory activities, comprising stimulation of certain immune functions such as phagocytic activity of macrophages and suppression of the proinflammatory responses of epithelial cells to viruses and bacteria, which are manifested as alterations in secretion of various cytokines and chemokines. These immune modulations result from upregulation or downregulation of the relevant genes and their transcription factors. All these bioactivities can be demonstrated at noncytotoxic concentrations of extract and appear to be due to multiple components rather than the individual chemical compounds that characterize Echinacea extracts. Potential applications of the bioactive extracts may go beyond their traditional uses.

We studied the protective effects of Echinacea purpurea against radiation by evaluating changes in the peripheral blood cell count and peripheral blood antioxidant activity. E. purpurea administration had a suppressive effect on radiation-induced leukopenia, especially on lymphocytes and monocytes, and resulted in a faster recovery of blood cell counts. Mouse peripheral blood antioxidant activity was increased by E. purpurea, and a relationship between the suppressive effect on radiation-induced leukopenia and the antioxidant effect was suggested. Furthermore, we reviewed the evidence of augmentation of found in this study humoral immunity. The effects of immune activation by E. purpurea were investigated by measuring total immunoglobulin (IgG, IgM). The radioprotective effects of immune activation by E. purpurea were investigated by measuring T lymphocyte subsets in the peripheral blood of mice following whole-body irradiation. E. purpurea activates macrophages to stimulate IFN-gamma production in association with the secondary activation of T lymphocytes, resulting in a decrease in IgG and IgM production. Cytokines released from macrophages in mouse peripheral blood after E. purpurea administration activated helper T cells to proliferate. In addition, it is reported that activated macrophages in association with the secondary T lymphocyte activation increases IFN-gamma production and stimulates proliferation of cytotoxic T cells and suppressor T cells. We think that CD 4 and CD 8 subsets were more immunologically enhanced by E. purpurea than helper T cells and suppressor T cell these results reflect activation. In addition, we think that these results reflect cell-mediated immune responses.