Nuclear factor (NF)-kappa B regulates a central common signaling for immunity and cell survival. Artemisolide (ATM) was previously isolated as a NIF-kappa B inhibitor from a plant of Artemisia asiatica. However, molecular basis of ATM on NF-kappa B activation remains to be defined. Here, we demonstrate that ATM is a typical inhibitor of I kappa B kinase beta(IKK beta), resulting in inhibition of lipopolysaccharide (LPS)-induced NF-kappa B activation in RAW 264.7 macrophages. ATM inhibited the kinase activity of highly purified IKK beta and also LPS-induced IKK activity in the cells. Moreover, the effect of ATM on IKK beta activity was completely abolished by substitution of Cys-179 residue of IKK beta to Ala residue, indicating direct targeting site of ATM. ATM could inhibit I kappa B alpha. phosphorylation in LPS-activated RAW 264.7 cells and subsequently prevent NF-kappa B activation. Further, we demonstrate that ATM clown-regulates NF-kappa B-dependent TNF-alpha expression. Taken together, this study provides a pharmacological potential of ATM in NF-kappa B-dependent inflammatory disorders. (c) 2007 Elsevier Inc. All rights reserved.