4,2',5'-trihydroxy-4'-methoxychalcone from Dalbergia odorifera exhibits anti-inflammatory properties by inducing heme oxygenase-1 in murine macrophages.

Dalbergia odorifera T. Chen (Leguminosae) has traditionally been used as an ingredient in East Asian medicines to treat various diseases. In the present study, 4,2',5'-trihydroxy-4'-methoxychalcone (TMC), a biologically active chalcone isolated from the heartwood of D. odorifera, inhibited cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression, leading to a reduction in COX-2-induced prostaglandin E2 (PGE2) and iNOS-induced nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated murine peritoneal macrophages. Furthermore, TMC suppressed tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) production, and the phosphorylation and degradation of IκB-α as well as the LPS-stimulated nuclear translocation of p65 in macrophages. The present study also demonstrated that TMC induced heme oxygenase-1 (HO-1) expression through the nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) in macrophages. The effects of TMC on LPS-induced NO, PGE2, tumor necrosis factor (TNF)-α, and interleukin (IL)-1β production were partially reversed by the HO inhibitor tin protoporphyrin (SnPP). These results suggest that TMC inhibits pro-inflammatory mediators by inducing the expression of anti-inflammatory HO-1 via the Nrf2 pathway.