Cytotoxic constituents ofPilea mongolica.

Bioassay-guided fractionation of the aerial parts ofPilea mongolica (Urticaceae) afforded two cytotoxic triterpenoids, epi-oleanolic acid (I) and oxo-oleanolic acid (II). The structures of the compounds were confirmed by spectral and synthetic evidences. CompoundI and compoundII exhibited cytotoxicity against cultured human tumor cell lines, A549 (non small cell lung adenocarcinoma), SK-OV-3 (ovarian), SK-MEL-2 (skin melanoma), XF498 (CNS) and HCT15 (colon) with ED(50) values of 3.2 approximately 8.1 mug/ml and 0.7 approximately 6.8 mug/ml, respectively.