Phytochemical and immunomodulatory properties of an Echinacea laevigata (Asteraceae) tincture.

Echinacea preparations are consumed for the prevention or treatment of upper respiratory infections. The objective of this study was to provide the first data regarding the in vitro immunomodulatory properties of the American federally endangered species Echinacea laevigata (Asteraceae). Human peripheral blood mononuclear cells were cultured with root tinctures from E. laevigata, E. angustifolia, E. pallida, and E. purpurea. Cytokine production (tumor necrosis factor [TNF], interleukin [IL]-2, IL-10) and mononuclear cell proliferation were measured. High-performance liquid chromatography was used to assay levels of known bioactive compounds from all extracts tested to statistically determine whether there were relationships between extract phytochemical content and observed immune effects. E. laevigata extract was most similar to E. pallida extract and able to augment IL-10 and mononuclear cell proliferation, but not TNF or IL-2. Echinacoside, a caffeic acid derivative, correlated most strongly with results. This species may deserve continued investigation in both experimental and therapeutic contexts.