Eurycomalactone is a natural product isolated from Eurycoma longifolia Jack., acts as a potent NF-κB inhibitor( IC50 of 0.5 μM). Eurycomalactone inhibits protein synthesis, depletes cyclin D1, but does not affect TNFα-induced degradation of IκBα or the phosphorylation of IKKα/β and IκBα.