Undescribed sesquiterpene coumarins from the aerial parts of Ferula sinkiangensis and their anti-inflammatory activities in lipopolysaccharide-stimulated RAW 264.7 macrophages

Eight undescribed sesquiterpene coumarins (1–8) and twenty known ones (9–28), were isolated from the aerial parts of Ferula sinkiangensis K. M. Shen. Their structures were elucidated based on the comprehensive analysis of UV, IR, HRESIMS, 1D, and 2D NMR data. The absolute configuration of 1 was determined by single crystal X-Ray diffraction, while the absolute configurations of 2–8 were determined by comparisons of experimental and calculated electrostatic circular dichroism spectra. Compound 2 is the first hydroperoxy sesquiterpene coumarin from the genus Ferula, while compound 8 has an unusual 5′,8′-peroxo bridge. Griess reaction results indicated compound 18 significantly decreased nitric oxide production of the lipopolysaccharide-stimulated RAW 264.7 macrophages with an IC₅₀ value of 2.3 μM, and ELISA results revealed that compound 18 effectively inhibited tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 expressions.