Phenolic rich Cocos nucifera inflorescence extract ameliorates inflammatory responses in LPS-stimulated RAW264.7 macrophages and toxin-induced murine models.

Anti-inflammatory and antinociceptive effects of the acetone extract of Cocos nucifera (CnAE), an important ingredient in several traditional drugs, have been studied using different in vitro and in vivo models. CnAE did not show any observable toxicity in RAW264.7 macrophages by MTT assay. The calorimetric analysis (total COX, 5-LOX, MPO, iNOS and NO), ELISA (IL-1β, IL-6, TNF-α and PGE2) and qRT-PCR (IL-1β, IL-6, TNF-α and NF-κB) were performed in LPS-induced RAW264.7 macrophages. Phosphorylation of NF-κBp65 and IκB was determined by western blotting. CnAE (100 µg/mL) remarkably inhibited total COX (68.67%) and 5-LOX (63.67%) activities, and subsequent release of iNOS, NO and PGE2 (p ≤ 0.05) in RAW264.7 cells treated with LPS. ELISA showed CnAE markedly decreased the level of pro-inflammatory cytokines IL-1β (p ≤ 0.001), IL-6 (p ≤ 0.001) and TNF-α (p ≤ 0.001) in LPS treated RAW264.7 cells. CnAE (100 µg/mL) also significantly down-regulated the mRNA expressions of pro-inflammatory cytokines (IL-1β, p ≤ 0.05; IL-6, p ≤ 0.01 and TNF-α, p ≤ 0.001) and NF-κB (p ≤ 0.001) against LPS-induction. Moreover, LPS-induced phosphorylation of IκB-α and NF-κB p65 was significantly inhibited by CnAE (100 µg/mL). In vivo anti-inflammatory studies showed that CnAE (400 mg/kg) significantly inhibited carrageenan-induced acute paw oedema (59.81%, p ≤ 0.001) and formalin-induced chronic paw oedema (52.90%, p ≤ 0.001) in mice. CnAE at a dose of 400 mg/kg also showed a significant anti-nociceptive effect on acetic acid-induced writhing (48.21%, p ≤ 0.001) and Eddy's hot plate methods. These findings suggest that CnAE has significant anti-inflammatory and anti-nociceptive properties, mainly attributed to the inhibition of NF-κB/IκB signalling cascade.