Eremophilane sesquiterpene Lactones from Ligularia virgaurea ssp oligocephala

From an extract of the whole plant of Ligularia virgaurea ssp. oligocephola, three new eremophilane sesquiterpene lactones, 10alpha-hydroxy-1-oxoeremophila-7(11),8(9)-dien-12,8-olide (1), 6alpha,10alpha-dihydroxy-1-oxoeremophila-7(11),8(9)-dien-12,8-olide (2), 6beta,10beta-dihydroxyeremophila-7(11),8(9)-dien-12,8-olide (3), as well as four known sesquiterpene lactones with the same carbon skeleton, named toluccanolides A-C (4, 5, 7) and 6beta-hydroxy-8alpha-methoxyeremophila-1(10),7(11)-dien-12,8beta-olide (6) were isolated. Their structures were elucidated by spectroscopic methods including intensive 2D NMR techniques (gCOSY, gHMQC, gHMBC and H-1-H-1 NOESY for 2) and HR-ESI-MS.