A New Cytotoxic Cembrane Diterpene from the Roots of Euphorbia Pekinensis Rupr

A new cembrane diterpene, named (−)-(1S)-15-hydroxy-18-carboxycembrene, was isolated from petroleum ether extract of the roots of the Euphorbia pekinensis Rupr. To our knowledge, this compound is the first cembrane-type diterpenoid to be found in the family Euphorbiaceae. The structure was elucidated as (−)-(1S)-15-hydroxy-cembra -2E, 4Z, 7E, 11E-tetraen-18-oic acid by a combination of IR, HR-ESIMS, 1D- and 2D-NMR techniques. (−)-(1S)-15-hydroxy-18-carboxycembrene showed cytotoxic activity against all five human cancer cell lines tested.