New eremophilenolides from Ligulariopsis shichuana.

Four new eremophilenolides, 1-4, have been isolated from the whole plant of Ligulariopsis shichuana. Their structures were elucidated by spectroscopic methods, including 2D NMR experiments. Structures of compounds 1 and 2 were unequivocally established by X-ray diffraction experiments. All of these sesquiterpenes have eremophilane skeletons with 7(11)-en-8(12) lactone units. Compounds 1 and 2 showed moderate antibacterial activities against E. coli and B. subtilis.