We isolated the phenolic glucoside salicortin from a Populus euramericana bark extract, and examined its ability to suppress inflammatory responses as well as the molecular mechanisms underlying these abilities, using lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Salicortin inhibited iNOS expression and the subsequent production of NO in a dose-dependent manner in the LPS-stimulated RAW 264.7 cells. Salicortin significantly suppressed LPS-induced signal cascades of NF-κB activation, such as IKK activation, IκBα phosphorylation and p65 phosphorylation in RAW 264.7 cells. In addition, salicortin inhibited the LPS-induced activation of JNK, but not ERK or p38 MAPK. Furthermore, salicortin significantly inhibited production of pro-inflammatory cytokines, such as TNF-α, IL-1β and IL-6 in the LPS-stimulated RAW 264.7 cells. These findings suggest that salicortin may show its anti-inflammatory activity by suppressing the LPS-induced expression of pro-inflammatory mediators through inhibition of NF-κB and JNK MAPK signaling cascades in macrophages. [BMB Reports 2014; 47(6): 318-323]

No abstract

BackgroundInflammatory bowel diseases (IBDs) are chronic inflammatory disorders that are mediated by pathogenic Th1 and Th17 cells. Previous studies have demonstrated that taheebo water extract (TWE) derived from Tabebuia avellanedae Lorentz ex Griseb., as folk remedy, has been used to treat various inflammatory diseases. Although TWE has been previously shown to display anti-inflammatory activities, the in vivo effects of TWE on mucosal immune responses remain unclear.MethodsWe examined the anti-inflammatory effects of TWE on innate immune cells such as dendritic cells (DCs) and macrophages and also on the differentiation of T helper cells. Lastly, adopting a method for dextran sulfate sodium (DSS)-induced colitis, we investigated whether the oral administration of TWE can modulate mucosal inflammatory responses.ResultsWe found that TWE could activate DCs to produce immunosuppressive IL10 and polarize macrophages toward an anti-inflammatory phenotype in the mesenteric lymph node (MLN). Such alterations in DCs and macrophages resulted in a significant increase in anti-inflammatory Th2 and Foxp3+ Treg cells and a dramatic decrease in pro-inflammatory Th1 and Th17 cells in the MLN. Upon induction of colitis with DSS treatment, TWE significantly reduced the clinical symptoms, including body weight loss and colonic tissue inflammation, by up-regulating type II T helper immune responses.ConclusionsTaken together, these data suggest that TWE is an excellent natural product with therapeutic effects to help improve inflammatory disorders such as colitis.