X-Linked inhibitor of apoptosis (XIAP) is a protein which modulates several pathways, including several related to apoptosis. Embelin is a natural benzoquinone, isolated from plants of the genus Embelia, which directly binds and inhibits XIAP (IC50 = 4.1 μM). In this way, this cell-permeable inhibitor blocks growth while activating caspases and promoting apoptosis in cancer cells expressing high levels of XIAP. Presumably in an XIAP-dependent fashion, embelin (15-50 μM) also prevents NF-κB activation by inhibiting IKK. This compound also protects against XIAP- and caspase-dependent inflammation.
