Anti-Inflammatory Effects of Abeliophyllum distichum Nakai (Cultivar Okhwang 1) Callus through Inhibition of PI3K/Akt, NF-κB, and MAPK Signaling Pathways in Lipopolysaccharide-Induced Macrophages

Abstract

One of the Korean endemic plants, Abeliophyllum distichum Nakai (Oleaceae), contains acteoside, which is a glycoside exhibiting neuroprotective, anti-inflammation effects and antibacterial capacities. We conducted an investigation on the effects of the callus of A. distichum (cultivar Okhwang 1, CAO) on pro-inflammatory mediators released following nuclear factor-кB (NF-кB), phosphatidylinositol 3-kinase/Akt (PI3K-Akt) and mitogen-activated protein kinase (MAPK) signal activation in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Immunoblotting was employed to find out the expression of cyclooxygenase-2 (COX-2), inducible nitric oxide (iNOS), and activation of MAPK molecules, NF-κB and Akt. Cytokines, COX-2, and iNOS gene expression were assessed using polymerase chain reaction techniques. Cytokines, COX-2, and iNOS gene expression were assessed using polymerase chain reaction techniques. High-performance liquid chromatography revealed that CAO was rich in acteoside and isoacteoside. As a result, CAO inhibited the generation of NO, cytokines, COX-2, and iNOS expression. Further, translocation to the nuclear of NF-κB p65 and degradation of the inhibitor of NF-кB (IкB) were alleviated by suppressing phosphorylation. Additionally, CAO significantly impacted MAPK pathway activation by potentially reducing phosphorylation of MAPKs. These results indicate that the anti-inflammatory effect of CAO is mediated via the inhibition of MAPK, PI3K/Akt, and NF-κB signaling pathways, probably via glycosides, phenolics, and flavonoids bioactivity derived from plants. CAO can serve as a potential anti-inflammatory agent, which alleviates inflammation factors and act through specific cell signaling pathways.