Planta Med. 2003 Apr; 69(4): 375-7.

Two cytotoxic sesquiterpene lactones from the leaves of Xanthium strumarium and their in vitro inhibitory activity on farnesyltransferase.

Kim YS, Kim JS, Park SH, Choi SU, Lee CO, Kim SK, Kim YK, Kim SH, Ryu SY.

Two xanthanolide sesquiterpene lactones, 8- epi-xanthatin (1) and 8- epi-xanthatin epoxide (2), isolated from the leaves of Xanthium strumarium (Compositae), demonstrated a significant inhibition on the proliferation of cultured human tumor cells, i. e., A549 (non-small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nervous system) and HCT-15 (colon) in vitro. They were also found to inhibit the farnesylation process of human lamin-B by farnesyltransferase (FTase), in a dose-dependent manner in vitro (IC 50 value was calculated as 64 and 58 microM, respectively). Due to the relatively high concentrations of 1 and 2 required to obtain an FTase inhibition as compared with those necessary for a cytotoxic effect on tumor cells, it remains unclear whether a relationship between these two activities exists.