Two new sesquiterpene lactones from leaves of yacon, Smallanthus sonchifolius.

The chemical constituents of 95% EtOH extract of yacon leaves were separated to yield two new sesquiterpene lactones, together with three known compounds. The two new compounds were characterized to be 8ß-angeloyloxy-13-methoxyl-11, 13-dihydromelampolid-14-oic acid methyl ester (1) and 8ß-(3-methylbut-2-enoyl) oxy-13-methoxyl-11, 13-dihydromelampolid-14-oic acid methyl ester (2) on the basis of NMR spectra, HR-MS and other spectroscopic methods. The cytotoxicity of compounds 1-5 were evaluated on human hepatoma cell Bel-7402 and all the compounds showed moderate cytotoxicity.