Anti-inflammatory evaluation of the methanolic extract of Taraxacum officinale in LPS-stimulated human umbilical vein endothelial cells

BACKGROUND: Atherosclerosis is a chronic vascular inflammatory disease. Since even low-level endotoxemia constitutes a powerful and independent risk factor for the development of atherosclerosis, it is important to find therapies directed against the vascular effects of endotoxin to prevent atherosclerosis. Taraxacum officinale (TO) is used for medicinal purposes because of its choleretic, diuretic, antioxidative, anti-inflammatory, and anti-carcinogenic properties, but its anti-inflammatory effect on endothelial cells has not been established. METHODS: We evaluated the anti-inflammatory activity of TO filtered methanol extracts in LPS-stimulated human umbilical vein endothelial cells (HUVECs) by monocyte adhesion and western blot assays. HUVECs were pretreated with 100 μg/ml TO for 1 h and then incubated with 1 μg/ml LPS for 24 h. The mRNA and protein expression levels of the targets (pro-inflammatory cytokines and adhesion molecules) were analyzed by real-time PCR and western blot assays. We also preformed HPLC analysis to identify the components of the TO methanol extract. RESULTS: The TO filtered methanol extracts dramatically inhibited LPS-induced endothelial cell-monocyte interactions by reducing vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1, and pro-inflammatory cytokine expression. TO suppressed the LPS-induced nuclear translocation of NF-κB, whereas it did not affect MAPK activation. CONCLUSIONS: Our findings demonstrated that methanol extracts of TO could attenuate LPS-induced endothelial cell activation by inhibiting the NF-κB pathway. These results indicate the potential clinical benefits and applications of TO for the prevention of vascular inflammation and atherosclerosis.