Modulation of macrophage immune responses by Echinacea

Abstract

Echinacea preparations are widely used herbal medicines for the prevention 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 -KB, TNF-α and nitric oxide (NO). In cultured macrophages, all components except the monoene alkylamide (AA1) decreased lipopolysaccharide (LPS) stimulated NF-KB levels. 0.2 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 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 -KB, 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’.