One new antitumour cassane-type diterpene from Caesalpinia crista.

1α-acetoxy-5α, 7β-dihydroxycassa-11,13(15)-diene-16,12-lactone, a new cassane-type diterpene was isolated from Caesalpinia crista. The structure of this compound was elucidated by analysis of NMR spectra, and the relative configuration was established by NOE experiment. The new compound was evaluated for antitumour activity against T47D, DU145 and showed significant inhibitory activities.