ent-trachyloban-3beta-ol, a new cytotoxic diterpene from Croton zambesicus

The dichloromethane extract of leaves of Croton zambesicus (Euphorbiaceae) showing in vitro cytotoxicity against human cervix carcinoma cells was investigated in order to identify its active compounds. A bio-guided fractionation by HSCCC followed by MPLC led us to isolate a trachylobane diterpene, ent-trachyloban-3beta-ol, with cytotoxic properties (IC50 on HeLa cells = 7.3 microg/ml). This is the first report on the cytotoxicity of a trachylobane diterpene.