Inhibitory effects of tilianin on the expression of inducible nitric oxide synthase in low density lipoprotein receptor deficiency mice

We investigated the effect of tilianin upon inducible nitric oxide synthesis in the plasma of low-density lipoprotein receptor knock-out (LdIr-/-) mice fed with high cholesterol diet and in primary peritoneal macrophages of LdIr-/- mice. High cholesterol diet induced nitric oxide production in the plasma of LdIr-/- mice. Tilianin reduced the level of nitric oxide (NO) in plasma from LdIr-/- mice induced by the high cholesterol diet. Tilianin also inhibited the NO production from the primary culture of peritoneal macrophages treated with lipopolysaccharide. The inhibition of NO production was caused by the suppression of inducible nitric oxide synthase (iNOS) gene expression in peritoneal macrophages isolated from LdIr-/- mice. Moreover, tilianin inhibited the transcriptional activation of iNOS promoter that has NF-kappa B binding element. Thus, these results provide the first evidence that tillanin inhibit iNOS expression and production of NO and may act as a potential anti-inflammatory agent.