Diterpenoids from the Roots of Euphorbia fischeriana with Inhibitory Effects on Nitric Oxide Production

Bioactivity-guided isolation of a methanolic extract of Euphorbia fischeriana led to the isolation of four new abietane-type diterpenoids, fischeriolides A-D (1-4), together with 11 known diterpenoids. Their structures were elucidated based on the interpretation of 1D and 2D NMR spectroscopic and HRESIMS data. The absolute configuration of compound 3 was determined by single-crystal X-ray diffraction analysis and electronic circular dichroism methods. Compounds 5-9 exhibited inhibitory effects on LPS-induced nitric oxide production in RAW 264.7 macrophages with IC50 values in the range 4.9-12.6 μM.