Abstract

Three eremophilanolides, 1?-acetoxy-8?-methoxy-10? H-eremophil-7(11)-en-8?, 12-olide (1); 1?-angeloyloxy-6?-hydroxy-8?-methoxy-10? H-eremophil-7(11)-en-8?, 12-olide (2); and 1?-angeloyloxy-8?H, 10?H-eremophil-7(11)-en-8?, 12-olide (3), and two pyrrolizidine alkaloids, integerrimine (4) and its N-oxide (5), were isolated from bioactive fractions of Senecio miser. The structures of the new compounds 1 and 2 were established by NMR spectroscopic analysis and chemical transformation. The X-ray analysis of compound 1 was also performed. Eremophilanolides 1 and 2 and alkaloids 4 and 5 were found to be strong insect antifeedants, further supporting a proposed defensive role for these classes of compounds.