Eremophilane Sesquiterpenes With Antichlamydial Activity Isolated From Ligularia macrophylla

Three new eremophilane-type sesquiterpenoids (1-3), along with two known eremophilenolides (4-5), were obtained from the whole of Ligularia macrophylla. The structures were determined by spectroscopic analysis and comparison with reported data. Compounds 1-5 were evaluated for their antichlamydial activities by an experimental model employing L929 cells infected with Chlamydia abortus. Compound 3, at a concentration of 100 µM, exhibited activity comparable to that of the positive control tetracycline at a concentration of 20 µg/mL, while showing no cytotoxicity. Preliminary structure-activity relationships for these eremophilenolides are reported.