Cytotoxic sesquiterpenoids from Ligularia pleurocaulis.

The phytochemical investigation of whole plants of Ligularia pleurocaulis led to isolation of five sesquiterpenoids, including an eremophilenolide dimer named biligupleurolide, along with eight known sesquiterpenoids. Their structures were determined by spectroscopic methods including 2D NMR techniques, and the structures of biligupleurolide and ligupleurolide were confirmed by X-ray diffraction analysis. All of the isolated compounds were tested for their cytotoxic activity against three cancer cell lines (HepG2, A549 and MCF-7), and biligupleurolide showed moderate inhibitory activities, with IC50 values of 5.2, 5.6 and 8.4 μM against MCF-7, HepG2 and A549, respectively.