Anti-inflammatory and NF-κB inhibitory activity of aerial parts of Cestrum diurnum

Abstract Background Cestrum diurnum L. (Solanaceae) is used in various traditional medicine for pain and related disorders. The Malayali tribe of Tamil Nadu in India use the leaf in joint pain. In the Chinese traditional medicine it is used for the treatment of burns and swellings. Present study was designed to evaluate its traditional use in pain and inflammation. Methods Methanol extract of the aerial parts of C. diurnum was tested by carrageenan induced paw oedema and formalin induced paw licking test in mice at the oral doses of 150 and 300 mg/kg body weight. NF-κB inhibitory activity was evaluated by TNF-α induced NF-κB activation assay in RAW 264.7 macrophage cells at the concentration of 100 µg/ml. Results The extract, at the doses of 150 and 300 mg/kg, showed significant inhibition (p < 0.05) of carrageenan induced paw oedema and the effect persisted throughout the entire experimental period of 3 h with the highest activity (50% inhibition) at 3rd h. In formalin induced paw licking test, the extract exhibited significant (p < 0.05) inhibition of paw licking, both in the early and late phase of the experiment at the aforementioned dose levels. At the concentration of 100 µg/ml, the extract did not inhibit the nuclear translocation of NF-κB. Rather, the extract was found to downregulate NF-κB p65 protein expression. Conclusions The present work supports the folkloric use of the plant for its analgesic and anti-inflammatory action which might involve downregulation of NF-κB p65 protein expression and/or inhibition of autacoid (histamine, serotonin, prostaglandin) synthesis.