Costunolide, a sesquiterpene from the stem bark of Magnolia sieboldii, inhibits the RAS-farnesyl-proteintransferase

Costunolide, a germacrane sesquiterpene lactone isolated from the stem bark of Magnolia sieboldii demonstrated a significant inhibition upon the farnesylation process of human lamin-B by farnesyl-proteintransferase (FPTase), in a dose dependent manner in vitro (IC50 value was calculated as 20 microM). It was also found to exhibit an inhibition upon the proliferation of cultured human tumor cells, i.e., A549 (non small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nerve system) and HCT-15 (colon), in vitro.