Role of nuclear factor-κB and heme oxygenase-1 in the mechanism of action of an anti-inflammatory chalcone derivative in RAW 264.7 cells

1 The synthetic chalcone 3',4',5',3,4,5-hexamethoxy-chalcone (CH) is an anti-inflammatory compound able to reduce nitric oxide (NO) production by inhibition of inducible NO synthase protein synthesis. In this work, we have studied the mechanisms of action of this compound. 2 CH (10-30 muM) prevents the overproduction of NO in RAW 264.7 macrophages stimulated with lipopolysaccharide (1 mug ml(-1)) due to the inhibition of nuclear factor kappaB (NF-kappaB) activation. 3 We have shown that treatment of cells with CH results in diminished degradation of the NF-kappaB-IkappaB complex leading to inhibition of NF-kappaB translocation into the nucleus, DNA binding and transcriptional activity. 4 We also demonstrate the ability of this compound to activate NfE2-related factor (Nrf2) and induce heme oxygenase-1 (HO-1). 5 Our results indicate that CH determines a rapid but nontoxic increase of intracellular oxidative species, which could be responsible for Nrf2 activation and HO-1 induction by this chalcone derivative. 6 This novel anti-inflammatory agent simultaneously induces a cytoprotective response (HO-1) and downregulates an inflammatory pathway (NF-kappaB) with a mechanism of action different from antioxidant chalcones.