Cytotoxic sesquiterpene lactones from Pseudoelephantopus spicatus.

Five new sesquiterpene lactones, spicatolides D-H (1-5), along with four known compounds, pitocarphin D (6), 8 alpha-acetoxy-10 alpha-hydroxy-13-O-methylhirsutinolide (7), spicatolide A (8), and 13-O-methylvernojalcanolide 8-O-acetate (9), were isolated from an ethyl acetate extract of the aerial parts of Pseudoelephantopus spicatus. The structures of the new compounds were elucidated on the basis of spectroscopic data interpretation. All of the compounds isolated were evaluated for their cytotoxic effects against five human cancer cell lines. Compounds 1, 3, and 4 showed cytotoxicity (IC50 < 5 micro g/mL) against the Hep3B and MCF-7 cancer cell lines.