TOP 1 and 2, Taraxacum officinale polysaccharide, inhibit LPS stimulated inflammatory mediators via the NF‐κB and Akt inactivation in RAW 264.7 cells

It has been proposed that Taraxacum officinale polysaccharides (TOPs) have anti‐inflammatory and antioxidative effects in animal model. In this study, anti‐inflammatory activity of TOPs was investigated in lipopolysaccharide (LPS) stimulated RAW 264.7 cell line. TOPs were preincubated with various concentrations (0–4 mg/ml) and stimulated with LPS to induce inflammation. TOPs reduced LPS induced inducible nitric oxide synthase (iNOS), corresponding enzyme for NO production, and inflammatory cytokine, tumor necrosis factor (TNF)‐α, in macrophages than LPS‐only treated cells. TOP2 suppressed iNOS and TNF‐α expressions in a dose dependent manner, while TOP1 slightly suppressed them at the highest concentraiton. Phosphorylation of IκBα and p65, subunits of nuclear factor (NF)‐κB, was inhibited by both polysaccharides. Upstream signaling molecules, mitogen‐activated protein kinases (MAPKs) and Akt, of transcription factor were also measured and TOPs inhibited phosphorylation of Akt, but had no effect on extracellular signal‐regulated kinase (ERK), c‐Jun NH2‐terminal kinase (JNK), and p38. These results suggest that TOP 1 and 2 ameliorate LPS induced inflammation via inactivation of the NF‐κB and Akt pathways in RAW 264.7 cells; indeed, TOP 2 shows more potent anti‐inflammatory activity than that of TOP1.