Flavonoid, Phenol and Polysaccharide Contents of Echinacea Purpurea L. and Its Immunostimulant Capacity In Vitro

Abstract

Echinacea purpurea L. (EP) is a plant originally used by native Americans to treat respiratory infections and have long been used to aid in wound healing and to enhance the immune system. The purpose of this study was to demonstrate the ability of EP extracts to stimulate the production of nitric oxide (NO) and TNF-α as well as to evaluate the cell viability by the use of chicken peripheral blood mononuclear cells (PBMCs) and RAW 264.7 macrophages in vitro. The polysaccharides content of EP was 162.2±8.4 mg/g dry weight (DW)The EP extracted with a 55% ethanol at 55℃ contained 22.3 ±1.0 mg gallic acid equivalent/g DW of total phenolic compounds and 86.0 ± 4.6 mg quercetin equivalent/g of flavonoid content. The result of cell viability assay showed that 89% and 81% of chicken PBMCs and RAW 264.7 macrophages, respectively, were survived under the treatment of 3.2 mg/ml of EP extracts by microculture tetrazolium assays (MTAs). Moreover, the cell inhibitory activity did not show the 50% cyto-toxicity effect (IC50). In addition, NO production by stimulated chicken PBMCs and RAW 264.7 macrophages exhibited individually the linear relations with the concentration of EP extracts, and they were approximately 70 and 60 μM in 800 μg/ml, respectively. The tendency with the release of TNF-α by RAW 264.7 macrophages also corresponded with EP extracts concentration. It is concluded, EP extracts act as an immunostimulant for both tested cells but have no serious effect on inhibiting chicken PBMCs viability.