Protective effect of 5-hydroxy-3′,4′,7-trimethoxyflavone against inflammation induced by lipopolysaccharide in RAW 264.7 macrophage: in vitro study and in silico validation

The herb Lippia nodiflora L. (Verbenaceae) has been documented to exhibit anti-inflammatory, antipyretic, antitussive, antidiabetic, anticancer, and antimelanogenesis properties. In the present study, we aimed at evaluating the anti-inflammatory activity of 5-hydroxy-3′,4′,7-trimethoxyflavone, a flavonoid from L. nodiflora, using lipopolysaccharide induced inflammation in RAW 264.7 macrophages. 5-hydroxy-3′,4′,7-trimethoxyflavone significantly inhibited nitric oxide production and demonstrated slight reduction in prostaglandin-E2 level at tested concentrations. The production of pro-inflammatory cytokines, such as TNF-α, IL-6, and IL-1β, were obviously reduced by 5-hydroxy-3′,4′,7-trimethoxyflavone in a concentration-dependent manner. Moreover, 5-hydroxy-3′,4′,7-trimethoxyflavone significantly induced reduction in the mRNA expressions of inducible nitric oxide synthase and cyclooxygenase-2, representing that inhibition occurs at the transcriptional level. In addition, we performed molecular docking and molecular dynamic simulations to study the interaction of 5-hydroxy-3′,4′,7-trimethoxyflavone with inflammatory mediators such as inducible nitric oxide synthase and cyclooxygenase-2. Docking study showed its hydrogen bond interactions with key residues in the active site of inducible nitric oxide synthase and cyclooxygenase-2, enlightening its possible binding mode at the molecular level. The results of molecular dynamic simulations showed the stability of complexes and their interactions. Taken together, these findings envisage 5-hydroxy-3′,4′,7-trimethoxyflavone as a potential candidate molecule for the progress of therapeutic strategy against inflammation-related diseases.