Combretum Caffrum Confers a Potential CuttingEdge Anticancer Molecule as Combretastatins

Combretum caffrum (Combretaceae) commonly known as the South African bush willow tree grows naturally along the coast region of the East Cape of South Africa. Combretastatins are emerging chemical molecules discovered from C. caffrum tree capable of targeting colchicine binding sites; thus inhibiting the tubulin polymerization for the treatment of cancer. Numerous combretastatin analogues have been found in nature and created artificially, which showed strong cytotoxicity against a variety of cancers, including breast, colorectal, lung, kidney, ovarian, thyroid, liver, leukaemia, pancreatic, and cervical. Combretastatin A-4 was revealed to be the most potent antitumor agent in an isolated extract of C. caffum. Combretastatin A-4 is a pioneer in the development of anticancer medicines because of its distinctive features, which include a simple molecular structure, simple synthesis procedure, and antitubulin and antivascular activities. The objective of the present chapter is to elucidate the chemistry and biological activity of isolated combretastatins from C. caffrum, and to explore the development, mechanism of action, computer-aided drug design studies, and current clinical status as anticancer agents. As orphan drugs, the two Combretastatin A-4 analogs CA-4P and AVE8062 have been approved by the US Food and Drug Administration and the European Medicines Agency to treat anaplastic thyroid cancer (ATC), ovarian cancer, neuroendocrine tumors, gastro-enteropancreatic neuroendocrine tumors, and gliomas.

Keywords: Combretum caffrum, Anticancer, Combretastatins, Combretastatin A4.