[Main anticancer substances of vegetable origin]

During the last thirty years, the systematic screening of thousands of vegetal extracts has led to the isolation of numerous antitumor agents which belong to various chemical series. This paper only deals with some of them which are either of current clinical use or under advanced clinical experimentation, e.g., ellipticine, homoharringtonine, camptothecine, acronycine and their derivatives. The origin, the biological activity and its mechanism, and the toxicity of each of these alkaloids are described. These examples highlight the interest of the Plant Kingdom as source of biologically active new structures and the importance of a good knowledge of the mechanism of the activity and toxicity of active components. This knowledge gives a rational basis to prepare compounds of increased activity or reduced toxicity and to use them at their best in therapeutic.