The anti-inflammatory effects of E-α-(p-methoxyphenyl)-2′,3,4,4′-tetramethoxychalcone are mediated via HO-1 induction

• A novel chalcone induces HO-1 activity and protein without cytotoxic effects
• LPS-induced inflammatory cytokines are reduced in immune cells and epithelial cells.
• SOD-1, COX-2 and iNOS are suppressed by this chalcone.
• The mechanism includes regulation of NF-|B, Nrf2 and MAPK.

Inflammation plays a central role in the pathophysiology of many diseases. The inducible enzyme heme oxygenase-1 (HO-1) protects cells against inflammation and can be induced by electrophilic compounds like the chalcones (1,3-diphenylprop-2-enones) from the class of α,β-unsaturated carbonyl compounds. We hypothesized that the synthetic chalcone E-α-(p-methoxyphenyl)-2′,3,4,4′-tetramethoxychalcone (E-α-p-OMe-C6H4-TMC) exerts anti-inflammatory effects in RAW264.7, Jurkat lymphocytes and HK-2 cells via HO-1 induction.RAW264.7 cells were treated with lipopolysaccharide prior to E-α-p-OMe-C6H4-TMC treatment. Subsequently, HO-1 protein induction and activity were analyzed, as well as expression of pro- and anti-inflammatory mediators, transcription factors and mitogen-activated protein kinases to evaluate the possible molecular mechanism. These results were confirmed in human cell lines (Jurkat T-lymphocytes and HK-2 epithelial cells).We found that the E-α-p-OMe-C6H4-TMC exerts significant anti-inflammatory effects in a dose dependent manner, showing no toxic effects in LPS-treated RAW264.7 macrophages. E-α-p-OMe-C6H4-TMC induced HO-1 and SOD-1 protein expression and HO-1 enzyme activity, reduced the upregulation of COX-2 and iNOS, while inducing the translocation of Nrf2. NF-κB activity was attenuated following E-α-p-OMe-C6H4-TMC treatment accompanied by the downregulation of proinflammatory cytokines IL-1β, IL-6 and MCP-1. Pretreatment with E-α-p-OMe-C6H4-TMC revealed significant changes in phosphorylation of ERK and p38, but not JNK. These anti-inflammatory effects of E-α-p-OMe-C6H4-TMC were approved in Jurkat and HK-2 cells, furthermore revealing a downregulation of IL-8 and IL-10.In conclusion, it is tempting to speculate about E-α-p-OMe-C6H4-TMC as a new and non-toxic agent, inducing HO-1 in cells. This opens up new opportunities regarding the development of therapeutic agents using beneficial effects of HO-1 and its products.

A weak Michael acceptor is a new HO-1 inducer. Toxicity is one of the main issues when electrophiles are evaluated for drug development. The fine-tuning of enones led to the identification of a 1,2,3-triaryl-prop-2-enone as a novel HO-1 inducing molecule. This HO-1 inducer is a very weak Michael acceptor, but acts as a significant anti-inflammatory agent, activating Nrf2 and HO-1 as well as SOD-1 on the one hand, while concomitantly inhibiting NF-κB, COX-2, iNOS, IL-1β, IL-6, IL-8 and MCP-1.Figure optionsDownload as PowerPoint slide