6-methoxyflavone suppresses neuroinflammation in lipopolysaccharide-stimulated microglia through the inhibition of TLR4/MyD88/p38 MAPK/ NF-ΚB dependent pathways and the activation of HO-1/NQO-1 signaling

Background: Microglia-related neuroinflammation is associated with a variety of neurodegenerative diseases. Flavonoids have demonstrated different pharmacological effects, such as antioxidation, neuroprotection and anti-inflammation However, the effect of flavonoid 6-methoxyflavone (6-MeOF) on microglia-mediated neuro-inflammation remain unknown.Purpose: The current study aim to study the antineuroinflammatory effects of 6-MeOF in lipopolysaccharide-(LPS-) induced microglia in vitro and in vivo.Methods: Pretreatment of BV2 microglia cells with 6-MeOF for 1 h then stimulated with LPS (100 ng/ml) for 24 h. The expression levels of pro-inflammatory factors, NO and reactive oxygen species (ROS) were performed by the enzyme-linked immunosorbent assay (ELISA), Griess assay and flow cytometry. Western blotting was used to assess MAPK, NF-Kappa B signal transducer and antioxidant enzymes-related proteins. Analysis of ROS and microglial morphology was confirmed in the zebrafish and mice brain, respectively.Results: Our results demonstrated that 6-MeOF dose-dependently prevent cell death and decreased the levels of pro-inflammatory mediators in LPS-stimulated BV2 microglia cells. Phosphorylated NF-Kappa B/I Kappa B and TLR4/ MyD88/p38 MAPK/JNK proteins after exposure to 6-MeOF was suppressed in LPS-activated BV-2 microglial cells. 6-MeOF also presented antioxidant activity by reduction of NO, ROS, iNOS and COX-2 and the induction of the level of HO-1 and NQO1 expressions in LPS-activated BV2 microglial cells. Furthermore, we demonstrated that 6-MeOF inhibited LPS-induced NO generation in an experimental zebrafish model and prevent the LPS-induced microgliosis in the prefrontal cortex and substantia nigra of mice. Conclusion: These results explored that 6-MeOF possesses potential as anti-inflammatory and anti-oxidant agents against microglia-associated neuroinflammatory disorders.

Automated summary

The study investigated the anti-inflammatory and antioxidant effects of flavonoid 6-methoxyflavone (6-MeOF) in microglia-mediated neuroinflammation. The results demonstrated that 6-MeOF reduced the expression of pro-inflammatory mediators, inhibited the activation of NF-Kappa B and MAPK signaling pathways, decreased the levels of reactive oxygen species (ROS), and induced the expression of antioxidant enzymes. Furthermore, 6-MeOF prevented the proliferation of microglia. These findings suggest that 6-MeOF has the potential to be used as a therapeutic agent for neuroinflammatory disorders.