Inhibition of lipopolysaccharide-induced expression of inducible nitric oxide synthase and tumor necrosis factor-alpha by 2'-hydroxychalcone derivatives in RAW 264.7 cells

In cultures of the murine macrophage cell line RAW 264.7, effects of four 2'-hydroxychalcone derivatives, 2'-hydroxy-4'-methoxychalcone (compound 1), 2',4-dihydroxy-4'-methoxychalcone (compound 2), 2',4-dihydroxy-6'-methoxychalcone (compound 3) and 2'-hydroxy-4,4'-dimethoxychalcone (compound 4), on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and tumor necrosis factor (TNF)-alpha were examined. Compounds 1, 2 and 3 at 3-30microM inhibited the production with almost the same potency. Compound 4 showed no inhibitory activity. Compounds 1, 2 and 3 at 3-30microM inhibited the LPS-induced expression of inducible nitric oxide synthase (iNOS) and TNF-alpha mRNA. To clarify the mechanism involved, effects of compounds 1, 2 and 3 on the activation of nuclear factor (NF)-kappaB and activator protein-1 (AP-1) were examined. Both the LPS-induced activation of NF-kappaB and AP-1 were blocked by compounds 1, 2 and 3 at 3-30microM. Moreover, the three compounds at such concentrations inhibited the LPS-induced IkappaB degradation and the phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun. These findings suggest that the inhibition of the LPS-induced production of NO and TNF-alpha by the 2'-hydroxychalcone derivatives is due to the inhibition of NF-kappaB and AP-1 activations.