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Modulation of macrophage immune responses by Echinacea
Centre for Phytochemistry and Pharmacology, Southern Cross University, Australia
MediHerb Research Laboratories, University of Queensland, Australia
School of Health, University of New England, Australia
The Australian Centre for Complementary Medicine Education and Research, Southern Cross University, Australia
* Author to whom correspondence should be addressed.
Received: 3 December 2004; Accepted: 26 May 2005 / Published: 31 October 2005
Abstract: Echinacea preparations are widely used herbal medicines for the prevention and treatment of colds and minor infections. There is little evidence for the individual components in Echinacea that contribute to immune regulatory activity. Activity of an ethanolic Echinacea extract and several constituents, including cichoric acid, have been examined using three in vitro measures of macrophage immune function – NF-κB, TNF- α and nitric oxide (NO). In cultured macrophages, all components except the monoene alkylamide (AA1) decreased lipopolysaccharide (LPS) stimulated NF-κB levels. 0.2 μg/ml cichoric acid and 2.0μg/mL Echinacea Premium Liquid (EPL) and EPL alkylamide fraction (EPL AA) were found to significantly decrease TNF-α production under LPS stimulated conditions in macrophages. In macrophages, only the alkylamide mixture isolated from the ethanolic Echinacea extract decreased LPS stimulated NO production. In this study, the mixture of alkylamides in the Echinacea ethanolic liquid extract did not respond in the same manner in the assays as the individual alkylamides investigated. While cichoric acid has been shown to affect NF-κB, TNF-α and NO levels, it is unlikely to be relevant in the Echinacea alterations of the immune response in vivo due to its non- bioavailability – i.e. no demonstrated absorption across the intestinal barrier and no detectable levels in plasma. These results demonstrate that Echinacea is an effective modulator of macrophage immune responses in vitro.
Keywords: Echinacea; macrophages; nitric oxide; TNF-α; NF-κB; alkylamides.
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Stevenson, L.; Matthias, A.; Banbury, L.; Penman, K.; Bone, K.; Leach, D.; Lehmann, R. Modulation of macrophage immune responses by Echinacea. Molecules 2005, 10, 1279-1285.
Stevenson L, Matthias A, Banbury L, Penman K, Bone K, Leach D, Lehmann R. Modulation of macrophage immune responses by Echinacea. Molecules. 2005; 10(10):1279-1285.
Stevenson, L.; Matthias, A.; Banbury, L.; Penman, K.; Bone, K.; Leach, D.; Lehmann, R. 2005. "Modulation of macrophage immune responses by Echinacea." Molecules 10, no. 10: 1279-1285.