CHEMICAL STUDIES ON MEXICAN PLANTS USED IN TRADITIONAL MEDICINE .28. NEW TETRANORTRITERPENOIDS FROM SWIETENIA-HUMILIS

Four new tetranortriterpenoids, humilinolides A [1], B [2], C [3], and D [4], were isolated from the seeds of Swietenia humilis (Meliaceae). The structures of compounds 1-4 were established by spectroscopic met hods. The structure of humilinolide A [1] was confirmed unequivocally by single crystal X-ray diffraction studies. The effect of the MeOH ex tract of the seeds and the isolated terpenoids 1-4 on the radicle grow th of Amaranthus hypochondriacus and Echinochloa crus-galli was evalua ted. The extract and compounds 1 and 3 caused significant inhibition o n radicle elongation in both target species. In addition, the MeOH ext ract of seeds of S. humilis showed moderate inhibition to the growth a nd feeding of the third instar larvae of Tenebrio molitor.