Anethole blocks both early and late cellular responses transduced by tumor necrosis factor: Effect on NF-κB, AP-1, JNK, MAPKK and apoptosis

Anethole, a chief constituent of anise, camphor, and fennel, has been shown to block both inflammation and carcinogenesis, but just how these effects are mediated is not known. One possibility is TNF-mediated signaling, which has also been associated with both inflammation and carcinogenesis. In the present report we show that anethole is a potent inhibitor of TNF-induced NF-κB activation (an early response) as monitored by electrophoretic mobility shift assay, IκBα phosphorylation and degradation, and NF-κB reporter gene expression. Suppression of Iκ-Bα phosphorylation and NF-κB reporter gene expression induced by TRAF2 and NIK, suggests that anethole acts on IκBα kinase. Anethole also blocked the NF-κB activation induced by a variety of other inflammatory agents. Besides NF-κB, anethole also suppressed TNF-induced activation of the transcription factor AP-1, c-jun N-terminal kinase and MAPK-kinase. In addition, anethole abrogated TNF-induced apoptosis as measured by both caspase activation and cell viability. The anethole analogues eugenol and isoeugenol also blocked TNF signaling. Anethole suppressed TNF-induced both lipid peroxidation and ROI generation. Overall, our results demonstrate that anethole inhibits TNF-induced cellular responses, which may explain its role in suppression of inflammation and carcinogenesis.