Protective effects of syringin against lipopolysaccharide-induced acute lung injury in mice.

Background: Syringin, a major active substance isolated from Eleutherococcus senticosus, has been found to have anti-inflammatory effect. The aim of this study was to investigate the effects and underlying mechanisms of syringin on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice.

Methods: We established an LPS-induced ALI model in mice. We also detected the lung wet-to-dry ratio, myeloperoxidase activity, and inflammatory cytokines tumor necrosis factor alpha, interleukin (IL)-1β, and IL-6 to estimate the index of lung injury in mice. Furthermore, the expression of nuclear factor-erythroid 2-related factor-2 (Nrf2), heme oxygenase-1, and nuclear factor κB (NF-κB) was detected by Western blot analysis.

Results: The results showed that the increases in lung wet-to-dry ratio, myeloperoxidase activity, malondialdehyde content, and levels of tumor necrosis factor alpha, IL-1β, and IL-6 induced by LPS were significantly inhibited by treatment of syringin. The phosphorylation of IκB-α and p65 NF-κB caused by LPS was inhibited by syringin. Furthermore, syringin was found to upregulate the expression of Nrf2 and heme oxygenase 1.

Conclusions: In conclusion, the results suggest that syringin protects against LPS-induced ALI by activating Nrf2 and inhibiting NF-κB signaling pathway.