New Guaiane Sesquiterpene Lactones from Ixeris dentata

Three new guaiane-type sesquiterpene lactones (1-3), together with nine related sesquiterpenes (4-12), were isolated from the whole extract of Ixeris dentata (Asteraceae). The chemical structures of isolates 1-12 were established by spectroscopic analyses as 3 beta,8 beta-dihydroxy-guaia-10(14)-en-1 alpha,4 alpha,5 alpha,6 beta,7 alpha,11 beta H-12, 6 alpha-olide (1), ixerin N 6'-O-acetate (2), ixerisoside A 6'-O-acetate (3), ixerin N(4), ixerisoside A(5), ixerin M (6), tectroside (7), 8-epidesacylcynaropicrin glucoside (8), 8-epiisolipidiol (9), 11 beta H-11, 13-dihydrointegrifolin (10) 8 beta-hydroxy-4 beta,15-dihydrozaluzanin C (11), and integrifolin (12). Compounds 1-12 were evaluated for their inhibitory effect on the proliferation of the cultured human tumor cell lines MES-SA, MES-SA/DX5, HCT-15, and HCT15/CL02 in vitro.