Cytotoxic diterpenoids from Euphorbia pekinensis.

A new diterpenoid, named euphpekinensin, along with three known diterpenoids, was isolated from the roots of Euphorbia pekinensis for the first time and the structures were elucidated by spectral analysis. The 2D-NMR techniques such as 1H-1H COSY, HMQC, HMBC and NOESY spectra were mainly applied to determine the structure of the new diterpenoid. The four diterpenoids showed cytotoxic activity against human KB cells in vitro.