Imperatorin Attenuates LPS-Induced Inflammation by Suppressing NF-κB and MAPKs Activation in RAW 264.7 Macrophages

Imperatorin is a type of coumarin compound with antibacterial and antiviral activities. In the present study, we examined the anti-inflammatory effects of imperatorin in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages by investigating its impact on the production and expression of cytokines and the major signal-transduction pathways. We found that imperatorin downregulated LPS-induced levels of TNF-α, IL-1β, and IL-6 in RAW 264.7 macrophages in a concentration-dependent manner, and it significantly inhibited expression of TNF-α and IL-6 (P < 0.05 or P < 0.01). The phosphorylation of mitogen-activated protein kinases and nuclear factor-kappaB (NF-κB) p65 protein were analyzed by western blotting. In RAW 264.7 macrophages treated with 1 mg/L of LPS, imperatorin significantly inhibited p38 and Jun N-terminal kinase phosphorylation protein expression. However, there was no significant change in p-ERK. Furthermore, imperatorin also inhibited NF-κB translocation into the nucleus through blockage of IκBα phosphorylation and degradation.