New sesquiterpenoids from Ligularia duciformis

From the whole plants of Ligularia duciformis, four new sesquiterpenoids, 3 beta-acetoxy-6 beta-methoxyeremophila-7(11),9(10)-dien-12,8 beta-olide (1), 3 beta-acetoxy-8 alpha-hydroxy-6 beta-methoxyeremophila-7(11),9(10)-dien-12,8 beta-olide (2), 3 beta-acetoxy-10 beta-hydroxy-6 beta,8 beta-dimethoxyeremophil-7(11)-en-12,8 alpha-olide (3), and 3 beta-acetoxy-6 beta,8 beta,10 beta-trihydroxyeremophil-7(11)-en-12,8 alpha-olide (4) were isolated. Their structures were established by high-field NMR techniques ((1)H,(1)H-COSY, (13)C-APT, HMQC, HMBC, and NOESY) and HR-ESI-MS analysis, together with comparison of the spectroscopic data with those of structurally related compounds. In addition, the cytotoxicity of the new compounds against human hepatic cancer cells Bel-7402, human pneumonic cancer cells A-549, and human colonic cancer cells HCT-8 were evaluated, the new compounds showed no cytotoxicity against the three tumor cells (all IC(50) values > 200 mu M).