A Novel Naturally Occurring Salicylic Acid Analogue Acts as an Anti-Inflammatory Agent by Inhibiting Nuclear Factor-kappaB Activity in RAW264.7 Macrophages

Methyl salicylate 2-O-beta-D-lactoside (DL0309), is a molecule chemically related to salicylic acid that is isolated from Gaultheria yunnanensis (FRANCH.) REHDER (G. yunnanensis). G. yunnanensis, a traditional Chinese herbal medicine, is widely used for treating rheumatoid arthritis, swelling, pain, trauma, and chronic tracheitis. In the present study, we explored the mechanism whereby DL0309 exerts anti-inflammatory effects, using the model of lipopolysaccharide (LPS)-treated RAW264.7 cells. We examined the effects of DL0309 on LPS-induced nuclear factor-kappaB (NF-kappa B) activity by Western blot analysis, cell imaging analysis and an electrophoretic mobility shift assay (EMSA). Production of pro-inflammatory cytokines was also measured. Our observations indicate that DL0309 suppressed production of nitric oxide (NO), reactive oxygen species (ROS) and the pro-inflammatory cytokines, such as tumor necrosis factor-a (TNF-alpha), interleukin-6 (IL-6), and interleukin-1 beta (IL-1 beta), in a concentration-dependent manner. The phosphorylation of IKK-beta and degradation of I kappa B-alpha by LPS were both inhibited by DL0309 in the cytoplasm. The increased protein level of NF-kappa B by LPS in the nucleus was also reduced by DL0309. Consistent with these results, we found that DL0309 prevents the nuclear translocation and DNA binding activity of NF-kappa B. Finally, our results demonstrate that DL0309 exerts anti-inflammatory effects, by inhibiting the production of pro-inflammatory cytokines and suppressing of the activation of the NF-kappa B signaling pathway in LPS-treated macrophage cells. Therefore, DL0309 may have therapeutic potential for treating inflammatory diseases by regulating the NF-kappa B pathway and pro-inflammatory cytokine production.