Cerbera manghas methanol extract exerts anti-inflammatory activity by targeting c-Jun N-terminal kinase in the AP-1 pathway

Ethnopharmacological relevance Cerbera manghas L. (Apocynaceae) is a medicinal plant traditionally used to ameliorate the clinical signs of inflammatory diseases and hypertension. Aim of study Although C. manghas L. has long been used as a traditional remedy for various diseases, the underlying molecular and cellular mechanisms are poorly understood. A detailed investigation of these mechanisms is necessary to demonstrate the ethnopharmaceutical utility of this plant. Materials and Methods The effects of C. manghas methanol extract (Cm-ME) on the production of inflammatory mediators and the expression of proinflammatory cytokines and identification of molecular targets were investigated using lipopolysaccharide (LPS)-treated macrophages in vitro. In addition, the inhibitory effects of Cm-ME orally administered were tested by LPS/D-galactosamine (D-GalN)-induced hepatitis and LPS-induced peritonitis mouse models in vivo. Results Cm-ME downregulated the production of prostaglandin (PG)E₂ and the mRNA expression of cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α, and interleukin (IL)-1β in LPS-stimulated RAW264.7 cells under non-toxic concentration of Cm-ME. This extract inhibited the nuclear translocation of c-Jun and p-ATF2, the phosphorylation of JNK and p38, and AP-1 activity. Western blot analysis and in vitro kinase assay confirmed that JNK is a direct pharmacological target of Cm-ME action. In addition, Cm-ME significantly ameliorated the clinical signs of LPS/D-GalN-induced hepatitis and lowered the production of nitric oxide (NO) and the phosphorylation of JNK in LPS-induced peritonitis conditions. Conclusion Cm-ME exerts anti-inflammatory actions on LPS-stimulated macrophages and in mouse models of acute inflammatory disease. These actions are predominantly mediated by targeting JNK in the AP-1 signaling pathway.