Curcumenol isolated from Curcuma zedoaria suppresses Akt-mediated NF-κB activation and p38 MAPK signaling pathway in LPS-stimulated BV-2 microglial cells

Food Funct. 2015 Nov;6(11):3550-9. doi: 10.1039/c5fo00607d. Epub 2015 Aug 24.

Abstract

Curcumenol, a sesquiterpene isolated from Curcuma zedoaria is known to possess a variety of health and medicinal values which includes neuroprotection, anti-inflammatory, anti-tumor and hepatoprotective activities. The current study aim is to investigate the modulatory effects of curcumenol towards the lipopolysaccharides (LPS)-induced inflammation in BV-2 microglia. Curcumenol markedly decreased LPS-induced production of nitric oxide (NO), pro-inflammatory cytokines [(IL-6) and (TNF-α)] and pro-inflammatory proteins expression, iNOS and COX-2. Moreover, curcumenol inhibited NF-κB activation by suppressing the nuclear translocation of the NF-κB p65 subunit and blocking IκBα phosphorylation and degradation. Furthermore, an NF-κB inhibitor, ethyl 3,4-dihydroxycinnamate also known as caffeic acid ethyl ester (CAEE), attenuated LPS-stimulated iNOS and COX-2 expression, suggesting that NF-κB inhibition is a regulator in the expression of iNOS and COX-2 proteins. Further mechanistic study with an Akt inhibitor, triciribine hydrate (API-2), revealed that curcumenol acted through Akt-dependent NF-κB activation. Moreover, curcumenol inhibition on LPS-induced phosphorylation of p38 MAPK is confirmed by its inhibitor (SB 202190). These results indicate that curcumenol diminishes the proinflammatory mediators and the expression of the regulatory genes in LPS-stimulated BV-2 by inhibiting Akt-dependent NF-κB activation and downregulation of Akt and p38 MAPKs signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / pharmacology*
  • Curcuma / chemistry
  • Cytokines / metabolism
  • Down-Regulation / drug effects
  • Inflammation / chemically induced
  • Inflammation / drug therapy*
  • Lipopolysaccharides
  • MAP Kinase Signaling System / drug effects*
  • Mice
  • Microglia / drug effects*
  • Microglia / metabolism
  • NF-kappa B / metabolism*
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase Type II / metabolism
  • Phosphorylation / drug effects
  • Phytotherapy*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Sesquiterpenes / isolation & purification
  • Sesquiterpenes / pharmacology*
  • Signal Transduction / drug effects

Substances

  • Anti-Inflammatory Agents
  • Cytokines
  • Lipopolysaccharides
  • NF-kappa B
  • Sesquiterpenes
  • curcumenol
  • Nitric Oxide
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse
  • Proto-Oncogene Proteins c-akt