Six new tigliane diterpenoids with anti-inflammatory activity from Euphorbia kansuensis

Six new tigliane diterpenoids, euphkanoids A ? F (1–6), along with 12 known diterpenoids (7–18) were isolated from the roots of Euphorbia kansuensis, a traditional Chinese medicinal plant. Their structures were elucidated by spectroscopic analysis, ECD calculation and chemical methods. Compounds 1–3 represent the unusual examples of tigliane diterpenoids with a conjugated olefinic aldehyde moiety. 1–18 and two hydrolyzed analogues (1c and 4a) were screened for the inhibitory effects on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in RAW264.7 cells. The results showed that 1–3 and 6 markedly inhibited NO production with IC₅₀ values in the range of 4.8–11.3 μM, which were more active than the positive control quercetin (IC₅₀ = 12.3 μM).