Bioactive lignan derivatives from the stems of Firmiana simplex.

The CHCl3 soluble fraction of the 80% MeOH extract of the stems of Firmiana simplex strongly inhibited nitric oxide production in lipopolysaccharide-activated BV-2 cells. A bioactivity-guided column chromatographic separation yielded two new lignans, firmianols A and B (1-2) together with seventeen known lignans (3-19). The structural elucidation of the new compounds was determined by spectroscopic methods, including 1D, 2D NMR and HR-FAB-MS. All isolated lignans were evaluated for their antineuroinflammatory effects on nitric oxide (NO) production in lipopolysaccharides (LPS)-activated murine microglia BV2 cells. Among the isolated, compounds 14 and 15 showed potent inhibitory activity against NO production (IC50 1.05 and 0.929 μM, respectively) without cell toxicity in murine microglia BV-2 cells. Compounds 11-13 and 17 also exhibited strong inhibitory effects on NO production, with IC50 values ranging from 7.07 to 15.28 μM.