Methyl jasmonate inhibits lipopolysaccharide-induced inflammatory cytokine production via mitogen-activated protein kinase and nuclear factor-κB pathways in RAW 264.7 cells.

Methyl jasmonate is an important signaling molecule involved in plant defense as well as in the regulation of plant growth and development. Despite its various functions in plants, its effects on animal cells have not been widely studied and no report has been issued on the molecular aspects of its anti-inflammatory effect. In the present study, we investigated the in vitro anti-inflammatory properties of methyl jasmonate in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Methyl jasmonate treatment effectively inhibited LPS-induced production of pro-inflammatory mediators (nitric oxide and prostaglandin E2) and cytokines (tumor necrosis factor-α, interleukin (IL)-1β, and IL-6) in a concentration-dependent manner. Furthermore, it attenuated the LPS-induced activation of nuclear factor-κB (NF-κB) by suppressing the degradation of the inhibitor of κB-α (IκB-α). Additionally, methyl jasmonate dose-dependently blocked the phosphorylation of mitogen-activated protein kinases (MAPKs), i.e., p38 kinase, extracellular signal-regulated kinase (ERK) 1/2, and c-Jun N-terminal kinase (JNK), in these cells. These results suggest that methyl jasmonate attenuated the LPS-induced release of pro-inflammatory mediators and cytokines by suppressing the activation of MAPK (JNK, ERK and p38) and NF-κB signaling. This study not only demonstrated that methyl jasmonate exerts anti-inflammatory activities in macrophages but also revealed its potential as a candidate for the treatment of various inflammation-associated diseases.