B-seco Limonoids with anti-inflammatory activity from Tetradium fraxinifolium (Hook.) T.G.Hartley.

Fraxinifolines A-F (1-6), six new B-seco limonoids, together with four known A,D-di-seco ones, were isolated from the twigs with leaves of Tetradium fraxinifolium. Their structures with absolute configurations were elucidated on the basis of analysis of MS, NMR, single-crystal X-ray diffraction and biogenetic pathway. An anti-inflammatory bioassay in vitro showed limonoids 1-3 had significant immunosuppressive effect against the production of pro-inflammatory cytokines (IL-1ß and/or TNF-α) in lipopolysaccharide (LPS)-stimulated RAW264.7 cells.