New sesquiterpene lactones from Ambrosia cumanensis Kunth.

Eleven sesquiterpene lactones, including three new natural products (1-3), were isolated from the n-butanolic extract of Ambrosia cumanensis Kunth. aerial parts. The structure of all isolated compounds was elucidated by 1D- and 2D-NMR, and MS analyses. All compounds were tested for their antiproliferative activity on HeLa, Jurkat, and U937 cell lines. Compound 3, 2,3-dehydropsilostachyn C, showed cytotoxic activity with different potency in all cell lines. By means of flow cytometric studies, compound 3 was demonstrated to induce in Jurkat cells a G2/M cell cycle block, while in U937 elicited both cytostatic and cytotoxic responses.