Urolithin A attenuates pro-inflammatory mediator production by suppressing PI3-K/Akt/NF-κB and JNK/AP-1 signaling pathways in lipopolysaccharide-stimulated RAW264 macrophages: Possible involvement of NADPH oxidase-derived reactive oxygen species

Eur J Pharmacol. 2018 Aug 15:833:411-424. doi: 10.1016/j.ejphar.2018.06.023. Epub 2018 Jun 20.


Urolithin A, a gut microbial metabolite of ellagic acid, is reported to exert anti-inflammatory effects in vitro and in vivo. However, complete mechanisms underlying the regulation of inflammatory responses by urolithin A remain unclear. This study aimed to evaluate the anti-inflammatory potential of urolithin A and its underlying mechanisms in lipopolysaccharide (LPS)-stimulated RAW264 macrophages. Urolithin A significantly attenuated the pro-inflammatory mediator production in LPS-stimulated RAW264 and mouse peritoneal macrophages. This compound significantly suppressed the LPS-elicited nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activation. The phosphorylation of Akt and c-Jun N-terminal kinase (JNK) was also inhibited by the treatment with urolithin A. Through experiments using kinase inhibitors, urolithin A abolished the LPS-induced phosphatidylinositol 3-kinase (PI3-K)/Akt/NF-κB and JNK/AP-1 signaling pathways, resulting in suppression of pro-inflammatory mediator production. Furthermore, treatment with this compound significantly reduced the intracellular accumulation of reactive oxygen species, which are known to act as secondary messengers in the activation of redox-sensitive transcription factors NF-κB and AP-1. Urolithin A treatment also diminished the LPS-evoked activation of NADPH oxidase (NOX), which is the main source of reactive oxygen species in activated macrophages. The inhibition of this activity by urolithin A led to the prevention of LPS-elicited NF-κB and AP-1 activation as well as Akt and JNK phosphorylation, resulting in the reduction of pro-inflammatory mediator production. Collectively, these results indicate that urolithin A treatment attenuates pro-inflammatory mediator production by suppressing NOX-derived reactive oxygen species-mediated PI3-K/Akt/NF-κB and JNK/AP-1 signaling pathways in LPS-stimulated macrophages.

Keywords: AP-1; Anti-inflammatory; Macrophage; NADPH oxidase; NF-κB; Urolithin A.

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / pharmacology*
  • Anti-Inflammatory Agents / therapeutic use
  • Coumarins / pharmacology*
  • Coumarins / therapeutic use
  • Inflammation / drug therapy*
  • Inflammation / immunology
  • Inflammation Mediators / metabolism
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Lipopolysaccharides / immunology
  • Male
  • Mice
  • Mice, Inbred ICR
  • Models, Animal
  • NADPH Oxidases / antagonists & inhibitors*
  • NADPH Oxidases / metabolism
  • NF-kappa B / metabolism
  • Peritoneum / cytology
  • Phosphatidylinositol 3-Kinase / metabolism
  • Phosphorylation / drug effects
  • Primary Cell Culture
  • Proto-Oncogene Proteins c-akt / metabolism
  • RAW 264.7 Cells
  • Reactive Oxygen Species / immunology
  • Reactive Oxygen Species / metabolism
  • Signal Transduction / drug effects*
  • Signal Transduction / immunology
  • Transcription Factor AP-1 / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Anti-Inflammatory Agents
  • Coumarins
  • Inflammation Mediators
  • Lipopolysaccharides
  • NF-kappa B
  • Reactive Oxygen Species
  • Transcription Factor AP-1
  • 3,8-dihydroxy-6H-dibenzo(b,d)pyran-6-one
  • NADPH Oxidases
  • Phosphatidylinositol 3-Kinase
  • Proto-Oncogene Proteins c-akt
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases