Four new eremophilanoid sesquiterpenes were siloated from Senecio oldhamianus. On the basis of spectroscopic and X-ray diffraction analysis, their structures were elucidated as : 7β,11-epoxy-9α,10α- epoxy-8-oxoeremophilane (1), 8-11-dioxol- 6-en-9α,10α-epoxy-8β- hydroxyeremophilane(2), 7(11)-en - 9α,10α-epoxy-8-oxoeremophilane (3), 6-en-9α,10α-epoxy-11- hydroxy-8-oxoeremophilane (4). The experiment of anticancer activity reveals that compound 1 promoted, while compound 2 and 3 inhibited, the growth of human hepatoma cells (SMMC-7721) and human ovarioncus cells (HO-8910).

Key words: SESQUITERPENE, X-RAY DIFFRACTION ANALYSIS, ANTINEOPLASTIC ACTIVITY, SENECIO SCANDENS