New myrsinol diterpenes from Euphorbia prolifera and their inhibitory activities on LPS-induced NO production

A phytochemical investigation of the roots of Euphorbia prolifera led to the isolation of ten new myrsinol diterpenes, named euphorbialoids A-J (1-10), and two known analogues (11 and 12). Their structures were elucidated on the basis of extensive 1D and 2D NMR (COSY, HMQC, HMBC and NOESY) spectroscopic data analyzes, and the structures of 1 and 9 were confirmed by X-ray crystallography. The inhibitory activities on LPS-induced NO production of these diterpenes were evaluated and all the compounds showed inhibitory effects.