Securinine is a tetracyclic alkaloid isolated from the roots of Securinega suffruticosa with an unusual structure in which the piperidine ring has a skewed boat form and the diene is not coplanar. Securinine inhibits [3H]GABA binding to rat brain membranes with an IC50 of approximately 50 µM. Securinine induces toll-like receptor (TLR)-independent macrophage activation in vitro, leading to IL-8 secretion, L-selectin down-regulation, and CD11b and MHC Class II antigen up-regulation. Securinine is an active antitumor agent, inducing p73-​dependent apoptosis preferentially in p53-​deficient colon cancer cells and inhibits the cell migration​/invasion ability of DU145 prostate cancer cells.