Bisabolane sesquiterpenes from the roots of Ligularia cymbulifera

Eight new highly oxygenated bisabolane sesquiterpenes (1-8), of which one contains a chlorine atom, were obtained in a phytochemical investigation of the roots of Ligularia cymbulifera, and their structures were elucidated by interpretation of spectroscopic data. Their relative configurations were clarified by a detailed analysis of (1)H NMR coupling constants and by NOE experiments. Compounds 1-8 were evaluated for antimicrobial activity against three bacterial cultures and a yeast culture.