Oral Presentation Joint Annual Scientific Meeting of the Nutrition Society of NZ and the Nutrition Society of Australia

Anti-inflammatory effects of polyphenol-rich propolis extracts by modulating ubiquitination of TRAF6 during NF-κB activation (169)

Kai Wang 1 , Lin Hu 2 , Xiao-Lu Jin 1 , Michael A Conlon 3 , David L Topping 3 , Fu-Liang Hu 1
  1. College of Animal Sciences, Zhejiang University, Hangzhou, China
  2. Life Sciences Institute, Zhejiang University, Hangzhou, China
  3. CSIRO Food and Nutrition Flagship, Adelaide, Australia

Background/Aims: Propolis is a resinous product collected by honeybees from polyphenol-rich plants. It has documented antioxidant and anti-inflammatory properties although its mechanisms of action are understood poorly. In this study, the anti-inflammatory effects of polyphenol-rich propolis extracts (PPE) from China (CPPE) and Brazil (BPPE) were examined.
Methods: Folin–Ciocalteu’s method and chromatographic analysis were used to compare their chemical compositions and in vitro antioxidant activities were measured using several different indices. The anti-inflammatory effects of PPE from China and Brazil were examined in murine endotoxin-induced inflammatory lung injury as well several cellular inflammation models.
Results: CPPE and BPPE showed differences in their polyphenolic composition and in vitro free radical scavenging activities. Oral administration of PPE to lipopolysaccharide (LPS)-challenged mice decreased serum proinflammatory cytokine concentrations and inhibited pulmonary nuclear factor (NF)-κB activation. Both PPE types modulated LPS-induced key inflammatory mediators and cytokine gene expression in RAW 264.7 macrophages. Reactive oxygen species (ROS) production and several inflammatory mediators were suppressed by both PPE types in a time and dose-dependent manner. In HeLa-T6RZC stable cells where NF-κB signalling is initiated at the level of TNF receptor-associated factor 6 (TRAF6), we found PPE suppressed NF-κB activation by delaying the ubiquitination of TRAF6. In an in vitro kinase assay system, both PPE types directly disrupted polyubiquitin synthesis by TRAF6.
Conclusions: Analysis showed substantial compositional differences between CPPE and BPPE, nevertheless they both displayed similar anti-inflammatory properties which may be useful as an alternative/additive therapeutic strategy against inflammation diseases like ulcerative colitis.
Funding sources: NSFC