Des poisons de flèches aux substances naturelles antimitoiques

The practical importanceo f arrow poisons is due to their physiological properties. Plant and animal species used in their preparation are numerous but most of the active compounds extracted from plants can be divided into threem ain chemical classes: alkaloids, cardiotonic glycosids and triterpenoids. In our laboratory, extensive studies on Strychnos usambarensis, the main constituent of an arrow poison used by the Banyambo of Rwanda, have led to the isolation of numerous quatemary or tertiary indole alkaloids. Because of the activity of a chloroformic extract of leaves on P-388 leukemia in vivo, we decided to test the antiproliferative microtest which has provebde stop ecific, selective, reproducible and quite inexpensive. Furthermore, only a few milligrams of crude extracts or pure alkaloids are necessary. The activity is determined against cultuBre 1d6 melanoma, flow 2002 normal embryonic lung, L1210 mouse ascites tumor and Hela human carcinoma cells. Thanks to this screening, we have selected the most active substances (strychnopentamine and dihydrousambarensine), on which we have performed more quantitative tests in vitro and in vivo and analysed their mode of action