Acer barbinerve Maxim belongs to the Aceraceae tree family and is often consumed as an Oriental medicine. In this study, we investigated whether or not ethanol extract from the bark of A. barbinerve Max. (EBA) inhibits lipopolysaccharide (LPS)-induced inflammatory responses in Raw264.7 macrophages. EBA was fractionated using n-hexane, CH2Cl2, ethyl acetate (EtOAc), and water. Raw264.7 cells were treated with 20 μg/mL of EBA and the EBA fractions. EBA inhibited LPS-induced nitric oxide (NO) production. Among the three fractions, EtOAc fraction of EBA (EFEBA) was the most effective in inhibiting LPS-induced NO production without significant cytotoxicity in Raw264.7 cells. EFEBA futher reduced LPS-induced expression of inducible NO synthase (iNOS) proteins and its corresponding mRNA. Additionally, EFEBA decreased the mRNA levels of interleukin (IL)-6, IL-1β, and tumor necrosis factor-α in LPS-treated Raw264.7 cells. Lastly, EFEBA inhibited LPS-induced degradation of the inhibitor of kappaBalpha (IκBα) as well as phosphorylation of p65 nuclear factor-κB (NF-κB). These results indicate that EFEBA exhibits strong anti-inflammatory effects and can be developed as a potential anti-inflammatory agent.

Keywords: Acer barbinerve Maxim, nitric oxide, pro-inflammatory cytokines, nuclear factor-κB