Dandelion (Taraxacum officinale) and Immune support: evidence and sources

Taraxasterol, a pentacyclic-triterpene, was isolated from the Chinese medicinal herb Taraxacum officinale. In the present study, we investigated the protective effect of taraxasterol on murine model of endotoxic shock and the mechanism of its action. Mice were treated with 2.5, 5 and 10 mg/kg of taraxasterol prior to a lethal dose of lipopolysaccharide (LPS) challenge. Survival of mice was monitored twice a day for 7 days. To further understand the mechanism, the serum levels of inflammatory cytokine tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-1β (IL-1β), interleukin-6 (IL-6) and mediator nitric oxide (NO), prostaglandin E₂ (PGE₂) as well as histology of lungs were examined. The results showed that taraxasterol significantly improved mouse survival and attenuated tissue injury of the lungs in LPS-induced endotoxemic mice. Further studies revealed that taraxasterol significantly reduced TNF-α, IFN-γ, IL-1β, IL-6, NO and PGE₂ levels in sera from mice with endotoxic shock. These results indicate that taraxasterol has a protective effect on murine endotoxic shock induced by LPS through modulating inflammatory cytokine and mediator secretion. This finding might provide a new strategy for the treatment of endotoxic shock and associated inflammation.

Plants of the genus Taraxacum officinale have a history of use in Korean, Chinese, Arabian and Native American traditional medicine to treat a variety of infectious diseases and cancers [1]. In Traditional Medicine, it is also known as choleretic, diuretic, anti-rheumatic and anti-inflammatory properties [2]. In the current study, in vitro immunostimulatroy effects of Taraxacum officinale have been investigated. The crude methanolic extract of the whole plant was sequentially fractionated into three subextracts; explicitly, ethyl acetate (EtOAc), n-butanol, and remaining water extracts. Further studies were carried out on the most active subextract, i.e. the EtOAc subextract, was further subjected to fractionation through successive column chromatographic applications on Silica gel 60. For the activity assessment, each extract or fraction was submitted to bioassay systems; in vitro neutrophil migration, spleen lymphocyte proliferation, nitric oxide (NO) production and phagocytosis for immunostimulatory activity assessment. Among the fractions, the ethyl acetate fraction was identified to be most effective in the migration activity of neutrophils, spleen cell proliferation, phagocytosis and NO production, significantly greater than media control. Sequential chromatographic separation of the ethyl acetate fraction on Silica gel column resulted in a more purified preparation that retained the immunostimulatory activity. From the EtOAc subextract, a major component was isolated and its structure was determined as taraxinic acid β-D-glucoside by means of spectral techniques.