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Title: Activities and prevalence of proteobacteria members colonizing Echinacea purpurea fully account for in vitro macrophage activation exhibited by extracts of this botanical

item HARON, MONA - University Of Mississippi
item Tyler, Heather
item PUGH, NIRMAL - University Of Mississippi
item MORAES, RITA - University Of Mississippi
item MADDOX, VICTOR - University Of Mississippi
item JACKSON, COLIN - University Of Mississippi
item PASCO, DAVID - University Of Mississippi

Submitted to: Planta Medica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2016
Publication Date: 6/10/2016
Citation: Haron, M.H., Tyler, H.L., Pugh, N.E., Moraes, R.M., Maddox, V.L., Jackson, C.R., Pasco, D.S. 2016. Activities and prevalence of proteobacteria members colonizing Echinacea purpurea fully account for in vitro macrophage activation exhibited by extracts of this botanical. Planta Medica. DOI:10.1055/s-0042-108590.

Interpretive Summary: Echinaea purpurea is one of the most popular immune enhancing botanicals in the United States herbal market and is used in the prevention and treatment of upper respiratory tract infections. However, there is substantial variation in immune stimulating activity between batches of Echinacea plant material. Prior research has demonstrated that cell wall components of bacteria colonizing Echinacea are responsible for the majority of this herb’s immune stimulating properties and that there is a link between immune activity and the amount of bacteria present in Echinacea tissue. Scientists at the University of Mississippi in Oxford and the USDA-ARS Crop Production Systems Research Unit in Stoneville, MS conducted a study to determine if variation in the type of bacteria present in Echinacea more completely accounts for the variability in the immune stimulating response. Of the bacterial isolates identified in Echinacea tissue, Proteobacteria were found to be the most potent stimulators of immune cells. Comparison of bacterial community composition and immune stimulating activity in 13 different Echinacea samples demonstrated that prevalence of Proteobacteria could fully account for the activities exhibited by these samples. The results of this study demonstrate that the type of bacteria colonizing an Echinacea plant can influence its efficacy as an immune enhancing herbal supplement.

Technical Abstract: Evidence supports the theory that bacterial communities colonizing Echinacea purpurea contribute to the innate immune enhancing activity of this botanical. Previously we reported that only about half of the variation in in vitro monocyte stimulating activity exhibited by E. purpurea extracts could be accounted for by total bacterial load within the plant material. In the current study we test the hypothesis that the type of bacteria, in addition to bacterial load, is necessary to fully account for extract activity. Bacterial community composition within commercial and freshly harvested (wild and cultivated) E. purpurea aerial samples was determined using high-throughput 16S rRNA gene pyrosequencing. Bacterial isolates representing 38 different taxa identified to be present within E. purpurea were acquired and the activity exhibited by extracts of these isolates varied by over 8,000-fold. Members of the Proteobacteria exhibited the highest potency for in vitro macrophage activation and were the most predominant taxa. Furthermore, the mean activity exhibited by the Echinacea extracts could be solely accounted for by the activities and prevalence of Proteobacteria members comprising the plant-associated bacterial community. The efficacy of E. purpurea material for use against respiratory infections may be determined by the Proteobacterial community composition of this plant, since ingestion of bacteria (probiotics) is reported to have a protective effect against this health condition.