Embelia Laeta aqueous extract suppresses acute inflammation via decreasing COX-2/iNOS expression and inhibiting NF-κB pathway

Abstract

Ethnopharmacological relevanceThe root of Embelia laeta (L.) Mez., which is called Suanjifeng in Chinese ethnic Yao medicine, is traditionally for inflammation-related diseases, such as oral ulcer, sore throat, enteritis, and rheumatoid arthritis. However, the biological properties and the underlying mechanisms of Embelia laeta still need further studies. Aim of this studyThe present study aims to investigate the anti-inflammatory effect and its underlying mechanisms of Embelia laeta. Materials and methodsIn this study, except acute toxicity experiments, Kunming (KM) mice of either sex were enrolled to establish inflammatory model induced by xylene, acetic acid and carrageenan, respectively. Mice were randomly divided into different groups and pretreated by oral gavage with different doses of Embelia laeta aqueous extract (ELAE) (2.5, 5, 10 g/kg) and 10 mg/kg of Indo for 7 days. Ear edema, vascular permeability, abdominal writhing, and paw edema degree were detected in related experiments. Moreover, in the carrageenan-induced paw edema mice model, histological changes were detected by H&E staining. MDA, MPO and NO were detected by assay kit. Proinflammatory cytokines of IFN-γ, TNF-α, IL-1β, IL-6 and PGE2 were detected by ELISA. Additionally, COX-2, iNOS and NF-κB pathway-related proteins were detected by Western blotting. ResultsResults showed that the ELAE evoked an obvious dose-dependent inhibition of ear edema induced by xylene, paw edema induced by carrageenan, as well as suppressing the increase of vascular permeability and writhing times elicited by acetic acid. Histopathological analysis indicated that ELAE could significantly decrease the cellular infiltration in paw tissue. ELAE showed antioxidant property through markedly decrease the MDA level and MPO activity in edema paw. In addition, ELAE decreased the proinflammatory cytokines IFN-γ, TNF-α, IL-1β, IL-6, PGE2 and NO that induced by carrageenan. Western blotting results also showed that ELAE could obviously downregulate the COX-2 and iNOS expression. Further analysis revealed that ELAE also inhibited NF-κB from the cytoplasm to the nucleus and stabilize the conversion of IκBα. ConclusionELAE had powerful anti-inflammatory property, which might be had a close relationship with mediating proinflammatory cytokines production, decreasing the COX-2 and iNOS expression, and inhibiting the activation of NF-κB signaling pathway.