The anti-inflammatory effect of 3-deoxysappanchalcone is mediated by inducing heme oxygenase-1 via activating the AKT/mTOR pathway in murine macrophages

Abstract

3-Deoxysappanchalcone (3-DSC), isolated from Caesalpinia sappan (Leguminosae), is a chalcone that exerts a variety of pharmacological activities. In the present study, we demonstrated that 3-DSC exerts anti-inflammatory activity in murine macrophages by inducing heme oxygenase-1 (HO-1) expression at the translational level. Treatment of RAW264.7 cells with 3-DSC induced HO-1 protein expression in a dose- and time-dependent manner without affecting HO-1 mRNA expression. Mitogen-activated protein kinase inhibitors or actinomycin D, a transcriptional inhibitor, did not block 3-DSC-mediated HO-1 induction. However, 3-DSC-mediated HO-1 induction was completely blocked by treatment with cycloheximide, a translational inhibitor, or rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR). Strikingly, 3-DSC increased the phosphorylation level of mTOR downstream target molecules such as eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and S6 kinase 1 (S6K1), as well as AKT in a dose- and time-dependent manner, suggesting that the 3-DSC induces HO-1 expression by activating the AKT/mTOR pathway. Consistent with the notion that HO-1 has anti-inflammatory properties, 3-DSC inhibited the production of nitric oxide (NO) and interleukin (IL)-6 in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Inhibition of HO-1 activity by treatment with tin protoporphyrin IX, a specific HO-1 inhibitor, abrogated the inhibitory effects of 3-DSC on the production of NO and IL-6 in LPS-stimulated RAW264.7 cells. Taken together, 3-DSC may be an effective HO-1 inducer at the translational level that has anti-inflammatory effects, and a valuable compound for modulating inflammatory conditions.

Keywords: 3-Deoxysappanchalcone; Anti-inflammatory effect; Heme oxygenase-1; Translation; mTOR.