A stilbenoid phenol, originally isolated from the bark of the African bush willow tree Combretum caffrum, with vascular disrupting and antineoplastic activities. Combretastatin targets and binds to the colchicine-binding site of tubulin, thereby impairs the polymerization of tubulin dimers and prevents the formation of microtubules in the endothelial cells of tumor. As a result, this may eventually lead to a destruction of the tumor vasculature, disruption of tumor blood flow and tumor cell necrosis.