Neuroprotective and anti-inflammatory effects of the flavonoid-enriched fraction AF4 in a mouse model of hypoxic-ischemic brain injury

PLoS One. 2012;7(12):e51324. doi: 10.1371/journal.pone.0051324. Epub 2012 Dec 12.

Abstract

We report here neuroprotective and anti-inflammatory effects of a flavonoid-enriched fraction isolated from the peel of Northern Spy apples (AF4) in a mouse of model of hypoxic-ischemic (HI) brain damage. Oral administration of AF4 (50 mg/kg, once daily for 3 days) prior to 50 min of HI completely prevented motor performance deficits assessed 14 days later that were associated with marked reductions in neuronal cell loss in the dorsal hippocampus and striatum. Pre-treatment with AF4 (5, 10, 25 or 50 mg/kg, p.o.; once daily for 3 days) produced a dose-dependent reduction in HI-induced hippocampal and striatal neuron cell loss, with 25 mg/kg being the lowest dose that achieved maximal neuroprotection. Comparison of the effects of 1, 3 or 7 doses of AF4 (25 mg/kg; p.o.) prior to HI revealed that at least 3 doses of AF4 were required before HI to reduce neuronal cell loss in both the dorsal hippocampus and striatum. Quantitative RT-PCR measurements revealed that the neuroprotective effects of AF4 (25 mg/kg; p.o.; once daily for 3 days) in the dorsal hippocampus were associated with a suppression of HI-induced increases in the expression of IL-1β, TNF-α and IL-6. AF4 pre-treatment enhanced mRNA levels for pro-survival proteins such as X-linked inhibitor of apoptosis and erythropoietin following HI in the dorsal hippocampus and striatum, respectively. Primary cultures of mouse cortical neurons incubated with AF4 (1 µg/ml), but not the same concentrations of either quercetin or quercetin-3-O-glucose or its metabolites, were resistant to cell death induced by oxygen glucose deprivation. These findings suggest that the inhibition of HI-induced brain injury produced by AF4 likely involves a transcriptional mechanism resulting from the co-operative actions of various phenolics in this fraction which not only reduce the expression of pro-inflammatory mediators but also enhance pro-survival gene signalling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / pharmacology*
  • Chromatography, Liquid
  • Disease Models, Animal
  • Flavonoids / pharmacology*
  • Hypoxia-Ischemia, Brain / prevention & control*
  • Mice
  • Neuroprotective Agents / pharmacology*
  • Tandem Mass Spectrometry

Substances

  • Anti-Inflammatory Agents
  • Flavonoids
  • Neuroprotective Agents

Grants and funding

This work was supported by grants from the Nova Scotia Heart and Stroke Foundation (Robertson), Atlantic Innovation Funds (Rupasinghe),Proof-of-Concept Award (Springboard Atlantic Inc.; Robertson and Rupasinghe), Natural Sciences and Engineering Council of Canada (Rupasinghe) and MS Society of Canada (Robertson). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.