Taxifolin attenuates inflammation via suppressing MAPK signal pathway

Objective: Taxifolin is a natural flavonoid compound that can be isolated from onions, grapes, oranges and grapefruit. It also acts as a medicine food homology with extraordinary antioxidant and anti-inflammatory activity. This study aims to explain the protective effects and potential mechanisms of taxifolin against inflammatory reaction. Methods: Levels of interleukin (IL)-6, IL-1β and intracellular reactive oxygen species (ROS) were assessed in different time after the treatment of taxifolin in RAW264.7 cells induced by lipopolysaccharide (LPS). Subsequently, the mRNA and protein levels of inducible nitric oxide synthase (iNOS), vascular endothelial growth factor (VEGF), cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α and the phosphorylation expression levels of the MAPK signal pathway were also evaluated. A silico analysis was used to explain the binding situation for the investigation of taxifolin and MAPK signal pathway. And then MAPK inhibitors were used to reveal the expression level of iNOS, VEGF, COX-2 and TNF-α in RAW264.7 cells. Results: It was demonstrated that cell inflammatory damage induced by LPS was significantly alleviated after the treatment of taxifolin. Then, the mRNA and protein levels of iNOS, VEGF, COX-2 and TNF-α were reduced and the phosphorylation expression levels of the MAPK signal pathway were down-regulated remarkably as well. In silico analysis, taxifolin could form a relatively stable combination with MAPK signal pathway. MAPK inhibitors showed increasing or decreasing effect in the mRNA levels of iNOS, VEGF, COX-2 and TNF-α, which suggesting that taxifolin down-regulated iNOS, VEGF, COX-2 and TNF-α expressions were not entirely through the MAPK pathway. Conclusion: This finding demonstrated that taxifolin improved the inflammatory responses that partly involved in the phosphorylation expression level of MAPK signal pathway in RAW264.7 cells exposed to acute stress.