Inhibition of lipopolysaccharide-induced inducible nitric oxide synthase and cyclooxygenase-2 expression by xanthanolides isolated from Xanthium strumarium

Three sesquiterpenoids, xanthatin (1), xanthinosin (2), and 4-oxo-bedfordia acid (3) were isolated from Xanthium strumarium as inhibitors of nitric oxide synthesis in activated microglia (IC50 values: 0.47, 11.2, 136.5 μM, respectively). Compounds 1 and 2 suppressed the expression of iNOS and COX-2 and the activity of NF-κB through the inhibition of LPS-induced I-κB-α degradation in microglia.