Tetranortriterpenoids fromClausena excavata

Five new tetranortriterpenoids, (11beta)-21,23-dihydro-11,21-dihydroxy-23-oxoobacunone (=21,23-dihydro-21-hydroxy-231-oxozapoterin: 2), (11beta)-21,23-dihydro-11,23-dihydroxy-21-oxoobacunone (=21,23-dihydro-23-hydroxy-21-oxozapoterin; 3), (1alpha,11beta)-1,2,21,23-tetrahydro-1,11,23-trihydroxy-21-oxoobacunone (=21,23-dihydro-23-hydroxy-21-oxoclausenarin; 4), (1alpha,11beta)-23-ethoxy-1,2,21,23-tetrahydro-1,11-dihydroxy-21-oxoobacunone (=23-ethoxy-21,23-dihydro-21-oxoclausenarin; 5); (11beta)-1,2,21,23-tetrahydro-11,23-dihydroxy-21-oxoobacunoic acid; 6), were isolated from the aerial part of Clausena excavata BURM. F. (Rutaceae). All compounds possessed 3,4-seco skeletons. Their structures were established by spectroscopic studies. Tetranortriterpenoids with a 4-hydroxybut-2-eno-4-lactone moietv are rarely found in the genus Clausena.