The extraction, stability, metabolism and bioactivity of the alkylamides in Echinacea spp.

Abstract

The fatty acid amides, a structurally diverse endogenous congener of molecules active in cell signaling, may prove to have diverse activity due to their interface with a number of receptor systems, including, but not limited to cannabinoid receptor 2 (CB2) and PPARγ. Select extracts of Echinacea spp. contain the fatty acid amides known as alkylamides. These extracts were a previously popular remedy relied on by U.S. physicians, one of the top sellers in the natural products industry and are currently a frequently physician prescribed remedy in Germany. In the series of experiments contained within, Galenic ethanolic extracts of Echinacea spp. root were used for the quantification, identification, degradation and bioactivity studies. On extraction, depending on the ratio of plant to solvent and fresh or dry, the data indicate that there is variability in the alkylamide classes extracted. For example the acetylene alkylamides appear to extract under different concentrations, as well as degrade faster than the olefinic alkylamides. In addition, the alkylamides are found to degrade significantly in both cut/sift and powdered forms of echinacea root. Human liver microsome oxidation of the major alkylamide dodeca-2E,4E,8Z,10Z-tetraenoic acid isobutylamide generate hydroxylated, caboxylated and epoxidized metabolites. The carboxylated metabolite has, thus far, shown different immune activity than the native tetraene isobutylamide. Bioactivity studies, based on cytokine modulation of the alkylamides have been assumed to be due to a classic CB2 response. However, the results of experiments contained herein suggest that IL-2 inhibition by the alkylamide undeca-2E-ene-8,10-diynoic acid isobutylamide, which does not bind to CB2, is due to PPARγ activation. These data, combined with data generated by other groups, suggest that the alkylamides of Echinacea spp. are polyvalent in effect, in that they modulate multiple biochemical pathways.