Découvertes récentes dans la chimie des alcaloïdes du Strychnos usambarensis GILG

Six bis-indole alkaloids have been isolated from the rootbark of Strychnos usambarensis.Four alkaloids ( usambarensine and derivatives) are unsymmetrical bis-indole products, biogenetically derived from two tryptaminic and one monoterpene units as some alkaloids of Apocynaceae (Ochrosia) and Rubiaceae ( Uncaria), two families very close to Loganiaceae from a chemotaxonomy point of view. Two other alkaloids (C-dihydrotoxiferine and C_Curarine) are symmetrical bis-indole quaternary products. These potent compounds were previously isolated from calabash-curare and some American Strychnos. Furthermore, we have isolated loganic acid and discussed the part that it could take in the biogenesis of various alkaloids.