Discovery of four modified classes of triterpenoids delineated a metabolic cascade: compound characterization and biomimetic synthesis

Abstract

Chemical studies onDichapetalum gelonioideshave afforded 18 highly modified complex triterpenoids belonging to four compound classes as defined by the newly adapted functional motifs associated with the A ring of the molecules. Their structures were determined by solid data acquired by diverse methods. The biosynthetic pathway for the four compound classes was rationalizedviacascade modifications involving diverse chemical events. The subsequent biomimetic syntheses afforded all the desired products, including compounds16and19that were not obtained in our purification, which validated the proposed biosynthetic pathway. Besides, some compounds exhibited strong cytotoxic activities, especially2and4showed nanomolar potency against the NAMALWA tumor cell line, and a gross structure-activity relationship (SAR) of these compounds against the tested tumor cell lines was delineated.