Terpenoids from the roots of Ligularia muliensis

Three new eremophilane-type sesquiterpenes, (6 beta,8 alpha)-6-(acetyloxy)-8-hydroxyeremophil-7(11)-en-12.8-olide (1). (6 alpha,8 alpha)-6-hydroxyeremophil-7(11)-cn-12.8-olide (2), and (6 alpha,8 alpha)-6-(acetyloxy)eremophil-7(11)-en-12,8-olide (3) ((8 alpha)-eremophil-7(11)-en-12,8-olide (4aR,5S,8aR,9aS)-4a,5,6,7,8,8a,9,9a-octahydro-3.4a.5-trimethylnaphtho[2,3-b]furan-2(4H)-one), besides the recently elucidated eremoliguarin (4) and bieremoligularolide (5), as well as a new highly oxygenated monoterpene, rel-(1R.2R.3R.4S,5S)-p-menthane-1,2,3,5-tetrol (12), together with six known constituents, i.e., the sesquiterpenes 6 and 7. the norsesquiterpenes 8-10, and the monoterpene 13, were isolated from the roots of Ligulariu mulietisis. In addition, an attempt to dimerize 1 to a bieremophilenolide (Scheme) resulted in the generation of the new derivative (6 beta,8 beta)-6-(acetyloxy)-8-chlorocremophil-7(11)-en-12,8-olide (11). The new structures were established by means of detailed spectroscopic analysis (IR, FAB-, El-, or HR-ESI-MS as well as 1D- and 2D-NMR experiments). Compounds 4 and 5 were evaluated for their antitumor effects in vitro (Table 3).