Phytochemical investigation and cytotoxic evaluation of the components of the medicinal plant Ligularia atroviolacea.

A phytochemical investigation of the roots of Ligularia atroviolacea resulted in the isolation of 24 compounds including seven new eremophilanoids named eremophila-3,7(11),8-triene-12,8;14,6alpha-diolide (1), 3beta-(angeloyloxy)eremophil-7(11)-en-12,8beta-olid-14-oic acid (2), 1alpha-chloro-10beta-hydroxy-6beta-(2-methylpropanoyloxy)-9-oxo-7,8-furoeremophilane (3), (10betaH)-8-oxoeremophila-3(4),6(7)-diene-12,14-dioic acid (4), (10alphaH)-8-oxoeremophila-3(4),6(7)-diene-12,14-dioic acid (5), 8beta-[eremophila-3',7'(11')-diene-12',8'alpha;14',6'alpha-diolide]eremophila-3,7(11)-diene-12,8alpha;14,6alpha-diolide (6), and ligulatrovine A (7), eleven known eremophilanoids, 8-18, four steroids, one glucose derivative, and one fatty acid. The structures of these compounds were elucidated by spectroscopic methods including 2D-NMR experiments. The structure of 3 was also established by an X-ray diffraction study. The in vitro cytotoxicity evaluation of selected compounds was performed on seven cultured tumor cell lines, i.e., KB, BEL-7404, A549, HL-60, HeLa, CNE, and P-388D1. The preliminary taxonomy of this species was also discussed, and the possible biogenesis of a dimer possessing a new noreremophilanoid type skeleton, 7, is presented in a preliminary form.