Neogenkwanine I from the flower buds of with its stereostructure confirmation using quantum calculation profiles and antitumor evaluation.

Neogenkwanine I (), a new daphnane-type diterpene with 4,7-ether group, along with four known ones (-), were isolated from . The structure including absolute configurations of was established on the basis of NMR, C-NMR and ECD calculations and CD exciton chirality analysis. C-NMR and ECD calculations of daphnane-type diterpenes were reported here for the first time. All of the diterpenes were screened for their cytotoxic activities against MCF-7 and Hep3B cell lines. The cytotoxicity structure- activity relationship of compounds was illustrated with the absence of ortho-ester group of daphnane-type diterpenes.