Echinacea preparations are commonly used as nonspecific immunomodulatory agents. Alcohol extracts from three widely used Echinacea species, Echinacea angustifolia, Echinacea pallida, and Echinacea purpurea, were investigated for immunomodulating properties. The three Echinacea species demonstrated a broad difference in concentrations of individual lipophilic amides and hydrophilic caffeic acid derivatives. Mice were gavaged once a day (for 7 days) with one of the Echinacea extracts (130 mg/kg) or vehicle and immunized with sheep red blood cells (sRBC) 4 days prior to collection of immune cells for multiple immunological assays. The three herb extracts induced similar, but differential, changes in the percentage of immune cell populations and their biological functions, including increased percentages of CD49+ and CD19+ lymphocytes in spleen and natural killer cell cytotoxicity. Antibody response to sRBC was significantly increased equally by extracts of all three Echinacea species. Concanavalin A-stimulated splenocytes from E. angustifolia- and E. pallida-treated mice demonstrated significantly higher T cell proliferation. In addition, the Echinacea treatment significantly altered the cytokine production by mitogen-stimulated splenic cells. The three herbal extracts significantly increased interferon-alpha production, but inhibited the release of tumor necrosis factor-gamma and interleukin (IL)-1beta. Only E. angustifolia- and E. pallida-treated mice demonstrated significantly higher production of IL-4 and increased IL-10 production. Taken together, these findings demonstrated that Echinacea is a wide-spectrum immunomodulator that modulates both innate and adaptive immune responses. In particular, E. angustifolia or E. pallida may have more anti-inflammatory potential.

Inhibition of prostaglandin E 2 (PGE 2 ) production in lipopolysaccharide-stimulated RAW264.7 mouse macrophage cells was assessed with an enzyme immunoassay following treatments with Echinacea extracts or synthesized alkamides. Results indicated that ethanol extracts diluted in media to a concentration of 15 μg/ mL from E. angustifolia, E. pallida, E. simulata, and E. sanguinea significantly inhibited PGE 2 production. In further studies, PGE 2 production was significantly reduced by all synthesized alkamides assayed at 50 μM, by Bauer alkamides 8, 12A analogue, and 14, Chen alkamide 2, and Chen alkamide 2 analogue at 25 μM and by Bauer alkamide 14 at 10 μM. Cytotoxicity did not play a role in the noted reduction of PGE 2 production in either the Echinacea extracts or synthesized alkamides. High-performance liquid chromatography analysis identified individual alkamides present at concentrations below 2.8 μM in the extracts from the six Echinacea species (15 μg/mL crude extract). Because active extracts contained 2, it is likely that alkamides may contribute toward the anti-inflammatory activity of Echinacea in a synergistic or additive manner.

The genus Echinacea is a popular herbal immunomodulator. Recent reports indicate that Echinacea products inhibit nitric oxide (NO) production in activated macrophages. In the present study we determined the inhibitory effects of alcohol extracts and individual fractions of alcohol extracts of Echinacea on NO production, and explored the mechanism underlying the pharmacological anti-inflammatory activity. The alcohol extracts of three medicinal Echinacea species, E. angustifolia, E. pallida and E. purpurea, significantly inhibited NO production by lipopolysaccharide (LPS)-activated the RAW 264.7 macrophage cell line, among them E. pallida was the most active. The Echinacea-mediated decrease in NO production was unlikely due to a direct scavenging of NO because the extracts did not directly inhibit NO released from an NO donor, sodium nitroprusside. An immunoblotting assay demonstrated that the extract of E. pallida inhibited inducible nitric oxide synthase (iNOS) protein expression in LPS-treated macrophages. The enzymes iNOS and arginase metabolize a common substrate, L-arginine, but produce distinct biological effects. While iNOS is involved in inflammatory response and host defense, arginase participates actively in anti-inflammatory activation. Arginase activity of RAW 264.7 cells stimulated with 8-bromo-cAMP was significantly increased by alcohol extracts of all three Echinacea species. The polar fraction containing caffeic acid derivatives enhanced arginase activity, while the lipophilic fraction containing alkamides exhibited a potential of inhibiting NO production and iNOS expression. These results suggest that the anti-inflammatory activity of Echinacea might be due to multiple active metabolites, which work together to switch macrophage activation from classical activation towards alternative activation.

No abstract

The correct spelling of the 6th's authors last name should Widrlechner.

Due to the popularity of Echinacea as a dietary supplement, researchers have been actively investigating which Echinacea constituent or groups of constituents are necessary for immune modulating bioactivities. Our prior studies indicate that alkylamides may play an important role in the inhibition of prostaglandin E2 (PGE2) production. HPLC fractionation, employed to elucidate interacting anti-inflammatory constituents from ethanol extracts of E. purpurea, E. angustifolia, E. pallida, and E. tennesseensis identified fractions containing alkylamides and ketones as key anti-inflammatory contributors using lipopolysaccharide induced PGE2 production in RAW264.7 mouse macrophage cells. Nitric oxide (NO) production and parallel cytotoxicity screens were also employed to substantiate an anti-inflammatory response. Echinacea pallida showed significant inhibition of PGE2 with a first round fraction, containing GC-MS peaks for Bauer Ketones 20, 21, 22, 23, and 24, with 23 and 24 identified as significant contributors to this PGE2 inhibition. Chemically synthesized Bauer Ketones 21 and 23 at 1 μM each significantly inhibited both PGE2 and NO production. Three rounds of fractionation were produced from an E. angustifolia extract. GC-MS analysis identified the presence of Bauer Ketone 23 in third round Fraction 3D32 and Bauer Alkylamide 11 making up 96% of third round Fraction 3E40. Synthetic Bauer Ketone 23 inhibited PGE2 production to 83 % of control and synthetic Bauer Alkylamide 11 significantly inhibited PGE2 and NO production at the endogenous concentrations determined to be present in their respective fraction, thus each constituent partially explained the in vitro anti-inflammatory activity of their respective fraction. From this study two key contributors to the anti-inflammatory properties of E. angustifolia were identified as Bauer Alkylamide 11 and Bauer Ketone 23.

It has been suggested that Echinacea has anti-inflammatory activity in vivo. Nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), and interleukin-1beta are important mediators in the inflammatory response. The effect of alcohol extracts of E. angustifolia (EA), E. pallida (EPA) and E. purpurea (EP) on the production of these inflammatory mediators in both LPS-stimulated RAW 264.7 macrophages in vitro and murine peritoneal exudate cells (PECs) in vivo were investigated. As macrophages produce these inflammatory mediators in response to pathogenic infection, parallel cultures of macrophages were studied for phagocytosis and intracellular killing of Salmonella enterica. EPA and EP in vitro inhibited NO production and TNF-α release in a dose-dependent manner. RAW 264.7 cells treated with EA or EP showed decreased killing over 24 h, although EA enhanced bacterial phagocytosis. Upon bacterial infection, RAW 264.7 cells produce high levels of NO; however, an Echinacea-mediated decrease in NO production was observed. Echinacea alcohol extracts administered orally at 130 mg/kg per day for seven days had a weak effect on NO production and phagocytosis by LPS-stimulated PECs. The results indicated that all Echinacea species significantly decreased inflammatory mediators in vitro, however, only EA and EP reduced bacterial killing. Oral administration of Echinacea alcohol extracts did not adversely affect the development and anti-bacterial function of inflammatory PECs in vivo, however, NO production was decreased during bacterial infection of PECs.

The genus Echinacea is used as an herbal medicine to treat a variety of ailments. To better understand its potential chemical variation, 40 Echinacea accessions encompassing broad geographical and morphological diversity were evaluated under controlled conditions. Metabolites of roots from these accessions were analyzed by HPLC-photo diode array (HPLC-PDA), GC-MS, and multivariate statistical methods. In total, 43 lipophilic metabolites, including 24 unknown compounds, were detected. Weighted principal component analysis (WPCA) and clustering analysis of the levels of these metabolites across Echinacea accessions, based on Canberra distances, allowed us to test two alternative taxonomic treatments of the genus, with the further goal of facilitating accession identification. A widely used system developed by McGregor based primarily on morphological features was more congruent with the dendrogram generated from the lipophilic metabolite data than the system more recently developed by Binns et al. Our data support the hypothesis that Echinacea pallida is a diverse allopolyploid, incorporating the genomes of Echinacea simulata and another taxon, possibly Echinacea sanguinea. Finally, most recognized taxa of Echinacea can be identified by their distinct lipophilic metabolite fingerprints.