Synthesis and anti-inflammatory activity of paeonol derivatives with etherized aryl urea by regulating TLR4/MyD88 signaling pathway in RAW264.7 cell.

Thirty-three novel paeonol etherized aryl urea derivatives (PEUs) were synthesized via a bromination-Williamson Ether Synthesis-deprotection-nucleophilic addition reaction sequence. The structures of PEUs were characterized by LC-MS, HRMS, 1H NMR and 13C NMR spectra. The levels of nitric oxide (NO), tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages were initially employed to evaluate the anti-inflammatory effects of all compounds. Remarkably, b16 exhibited a good anti-inflammatory activity at 2.5 μm which is the same as the potency of paeonol at 20 μm. The results of mechanism research displayed that the anti-inflammatory effect of b16 was ascribed to the inhibition of the TLR4/MyD88 signaling pathway and inflammatory factors. Additionally, b16 distinctly reduced the generation of free radicals in macrophages and strikingly increased the mitochondrial membrane potential. According to the structure-activity relationships (SAR) of PEUs, the incorporation of halogens on the benzene ring and the hydrogen of phenol hydroxyl substituted by aryl urea, were beneficial to enhance the anti-inflammatory activities. Molecular docking results illustrated that the binding ability of b16 to TLR4 was stronger than that of paeonol. In summary, the novel aryl urea-derivied paeonol b16 could be a new promising candidate for the treatment of inflammation-related diseases.