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

Wu-Fu Chen; Yao-Hsiang Shih; Hsuan-Chih Liu; Cheng-I Cheng; Chi-I Chang; Chung-Yi Chen; In-Pin Lin; Mei-Ying Lin; Chien-Hsing Lee

doi:10.1016/j.phymed.2022.154025

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

Phytomedicine. 2022 May:99:154025. doi: 10.1016/j.phymed.2022.154025. Epub 2022 Mar 1.

Authors

Wu-Fu Chen¹, Yao-Hsiang Shih², Hsuan-Chih Liu³, Cheng-I Cheng⁴, Chi-I Chang⁵, Chung-Yi Chen⁶, In-Pin Lin⁷, Mei-Ying Lin⁸, Chien-Hsing Lee⁹

Affiliations

¹ Department of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, No. 123 Dapi Road, Niaosong District, Kaohsiung, 83300, Taiwan; Department of Marine Biotechnology and Resources, National Sun Yat-sen University, No. 70 Lianhai Road, Gushan District, Kaohsiung City, 80424, Taiwan.
² Department of Anatomy, School of Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Sanmin District, Kaohsiung, 80708, Taiwan; Department of Medical Research, Kaohsiung Medical University Hospital, 100, Tzyou 1st Road, Sanmin District, Kaohsiung, 80756, Taiwan.
³ Department of Orthopedics, Chi Mei medical center, Liouying, Tainan, 73659, Taiwan.
⁴ Department of Medical Imaging, Sin-Lau Medical Foundation the Presbyterian Church, Tainan, 70142, Taiwan.
⁵ Department of Biological Science and Technology, National Pingtung University of Science and Technology, Pingtung, 91201, Taiwan; Research Center for Active Natural Products Development, National Pingtung University of Science and Technology, Pingtung, 91201, Taiwan.
⁶ Department of Nutrition and Health Science, School of Medical and Health Sciences, Fooyin University, Kaohsiung, 83102, Taiwan.
⁷ Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
⁸ Community Health Promotion Center, Kaohsiung Municipal Ci-Jin Hospital, Kaohsiung, 80708, Taiwan.
⁹ Department of Pharmacology, School of Post-Baccalaureate Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan; Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, 80708, Taiwan; Department of Biological Science and Technology, National Pingtung University of Science and Technology, Pingtung, 91201, Taiwan; Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: chlee0818@kmu.edu.tw.

PMID: 35272244
DOI: 10.1016/j.phymed.2022.154025

Abstract

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 neuroinflammation 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-κB 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-κB/IκB 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.

Keywords: 6-methoxyflavone; Anti-neuroinflammatory; Anti-oxidant; LPS; Microglia.