Phenylnaphthalene-type lignans have been recognized as the major anti-inflammatory constituents in V. negundo seeds, among which vitedoamine A (VA) was the first discovered lignan alkaloid bearing a γ-lactam. However, the protective effects and specific target of VA against rheumatoid arthritis (RA) have not been explored yet. Herein, our study revealed that VA could inhibit the transcriptional activity of NF-κB, and suppress the production of NO and reduce the expressions of inflammatory cytokines (IL-1β, IL-6, and TNF-α) in several inflammatory cell models, mainly via inhibiting the phosphorylation of IKKα/β and p65, and prevented the degradation of IκBα, thus restraining NF-κB activation. Meanwhile, VA considerably down-regulated the phosphorylation of IKKα/β and p65, and inhibited the degradation of IκBα in RANKL-induced osteoclasts formation and differentiation, suggesting that VA may impede osteoclastogenesis and relieve joint damage in RA. Furthermore, VA interfered IKK/IκBα/NF-κB pathway and decreased the expressions of inflammatory cytokines in IL-1β stimulated fibroblast-like synoviocytes (FLSs), suggesting that VA possessed promising in vitro anti-RA capacity, probably by direct targeting IKKβ and inhibiting its activity (IC