Pyrrolizidine Alkaloids and Bisabolane Sesquiterpenes from the Roots of Ligularia cymbulifera

The new pyrrolizidine alkaloid glycoside 1 , and the three new highly oxygenated bisabolane sesquiterpenes 4 – 6 , together with the two known pyrrolizidine alkaloids 2 and 3 , were isolated from the roots of Ligularia cymbulifera (W. W. Smith ) Hand .‐ Mazz . Their structures were established on the basis of spectroscopic analysis, especially 1D‐ and 2D‐NMR data. The cytotoxic activities of compounds 1, 2 , and 4 – 6 were evaluated against hepatoma (BEL‐7402), human leukemia (HL‐60), human ovarian carcinoma (HO‐8910), and nasopharyngeal carcinoma (KB) cell lines ( Tables 1–3 ). Compound 6 s howed weak cell‐growth inhibition of BEL‐7402 cell.