Ethanolic Echinacea purpurea Extracts Contain a Mixture of Cytokine-Suppressive and Cytokine-Inducing Compounds, Including Some That Originate from Endophytic Bacteria.
Echinacea preparations, which are used for the prevention and treatment of upper respiratory infections, account for 10% of the dietary supplement market in the U.S., with sales totaling more than $100 million annually. In an attempt to shed light on Echinacea's mechanism of action, we evaluated the effects of a 75% ethanolic root extract of Echinacea purpurea, prepared in accord with industry methods, on cytokine and chemokine production from RAW 264.7 macrophage-like cells. We found that the extract displayed dual activities; the extract could itself stimulate production of the cytokine TNF-α, and also suppress production of TNF-α in response to stimulation with exogenous LPS. Liquid:liquid partitioning followed by normal-phase flash chromatography resulted in separation of the stimulatory and inhibitory activities into different fractions, confirming the complex nature of this extract. We also studied the role of alkylamides in the suppressive activity of this E. purpurea extract. Our fractionation method concentrated the alkylamides into a single fraction, which suppressed production of TNF-α, CCL3, and CCL5; however fractions that did not contain detectable alkylamides also displayed similar suppressive effects. Alkylamides, therefore, likely contribute to the suppressive activity of the extract but are not solely responsible for that activity. From the fractions without detectable alkylamides, we purified xanthienopyran, a compound not previously known to be a constituent of the Echinacea genus. Xanthienopyran suppressed production of TNF-α suggesting that it may contribute to the suppressive activity of the crude ethanolic extract. Finally, we show that ethanolic extracts prepared from E. purpurea plants grown under sterile conditions and from sterilized seeds, do not contain LPS and do not stimulate macrophage production of TNF-α, supporting the hypothesis that the macrophage-stimulating activity in E. purpurea extracts can originate from endophytic bacteria. Together, our findings indicate that ethanolic E. purpurea extracts contain multiple constituents that differentially regulate cytokine production by macrophages.
Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Daniel A
DA
Todd
Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States of America.
Travis V
TV
Gulledge
Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Emily R
ER
Britton
Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Martina
M
Oberhofer
Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Martha
M
Leyte-Lugo
Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Ashley N
AN
Moody
Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Tatsiana
T
Shymanovich
Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Laura F
LF
Grubbs
Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States of America.
Monika
M
Juzumaite
Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Tyler N
TN
Graf
Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Nicholas H
NH
Oberlies
Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Stanley H
SH
Faeth
Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States of America.
Scott M
SM
Laster
Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America.
Nadja B
NB
Cech
D000577:Amides / Q000494:pharmacology; D000818:Animals; D001419:Bacteria / Q000737:chemistry*; D016923:Cell Death / Q000187:drug effects; D005591:Chemical Fractionation; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D020900:Echinacea / Q000737:chemistry* / Q000254:growth & development; D060026:Endophytes / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D051379:Mice; D010936:Plant Extracts / Q000494:pharmacology*; D011714:Pyrans / Q000737:chemistry / Q000494:pharmacology; D000067996:RAW 264.7 Cells; D012639:Seeds / Q000187:drug effects; D013329:Structure-Activity Relationship; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D014970:Xanthines / Q000737:chemistry / Q000494:pharmacology
D000577:Amides; D018925:Chemokines; D016207:Cytokines; D010936:Plant Extracts; D011714:Pyrans; D014409:Tumor Necrosis Factor-alpha; D014970:Xanthines; C532419:xanthienopyran; D000431:Ethanol