Anti-inflammatory Ingenane Diterpenoids from the Roots of Euphorbia kansui

Bioassay-guided fractionation of the ethanolic extract of the roots of Euphorbia kansui led to the isolation of two new ingenane diterpenoids, euphorkans A ( 1 ) and B ( 2 ), together with 16 known analogues ( 3  –  18 ). Their structures were determined by combined spectral and chemical methods. All the isolates were evaluated for their inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophage cells. Compounds 1  –  6 and 10  –  13 exhibited pronounced inhibitory activity with IC 50 values in the range of 2.78 – 10.6 µM, and were more potent than the positive control, quercetin (IC 50  = 15.8 µM). Compounds 1 and 5 were selected for further assays toward the key inflammation mediators TNF- α and IL-6, and showed a significant inhibition in a dose-dependent manner. The preliminary mechanistic study revealed that 1 and 5 inhibited NF- κ B activity, which may exert a role in their anti-inflammatory activity.