Cytokine-Suppressive Activity of a Hydroxylated Alkylamide from Echinacea purpurea

Echinacea purpurea has been widely used to treat upper respiratory tract infections. Bioassay-guided fractionation of hexane and ethanol extracts of this plant yielded 4[(2-methylbutyl)amino]-4-oxo-2-butenoic acid ( 1 ) and 8,11-dihidroxy-dodeca-2 E ,4 E ,9 E -trienoic acid isobutylamide ( 2 ), both of which are new to Echinacea . Compound 2 suppressed the production of TNF- α from RAW 264.7 cells with an IC 50 value of 6.8 µM, while 1 was inactive. Neither compound showed cytotoxicity at concentrations up to 100 µM. These findings support a growing body of literature demonstrating that E. purpurea contains an array of compounds that suppress cytokine secretion by macrophage-type cells in vitro .