Lack of enantiomeric influence on the brain cytoprotective effect of ibuprofen and flurbiprofen

Molecular Basis for Allosteric Inhibition of Acid-Sensing Ion Channel 1a by Ibuprofen

A growing body of evidence links certain aspects of nonsteroidal anti-inflammatory drug (NSAID) pharmacology with acid-sensing ion channels (ASICs), a small family of excitatory neurotransmitter receptors implicated in pain and neuroinflammation. The molecular basis of NSAID inhibition of ASICs has remained unknown, hindering the exploration of this line of therapy. Here, we characterized the mechanism of inhibition, explored the molecular determinants of sensitivity, and sought to establish informative structure-activity relationships, using electrophysiology, site-directed mutagenesis, and voltage-clamp fluorometry. Our results show that ibuprofen is an allosteric inhibitor of ASIC1a, which binds to a crucial site in the agonist transduction pathway and causes conformational changes that oppose channel activation. Ibuprofen inhibits several ASIC subtypes, but certain ibuprofen derivatives show some selectivity for ASIC1a over ASIC2a and vice versa. These results thus define the NSAID/ASIC interaction and pave the way for small-molecule drug design targeting pain and inflammation.

R-flurbiprofen attenuates experimental autoimmune encephalomyelitis in mice

R-flurbiprofen is the non-cyclooxygenase inhibiting R-enantiomer of the non-steroidal anti-inflammatory drug flurbiprofen, which was assessed as a remedy for Alzheimer's disease. Because of its anti-inflammatory, endocannabinoid-modulating and antioxidative properties, combined with low toxicity, the present study assessed R-flurbiprofen in experimental autoimmune encephalomyelitis (EAE) models of multiple sclerosis in mice. Oral R-flurbiprofen prevented and attenuated primary progressive EAE in C57BL6/J mice and relapsing-remitting EAE in SJL mice, even if the treatment was initiated on or after the first flare of the disease. R-flurbiprofen reduced immune cell infiltration and microglia activation and inflammation in the spinal cord, brain and optic nerve and attenuated myelin destruction and EAE-evoked hyperalgesia. R-flurbiprofen treatment increased CD4(+)CD25(+)FoxP3(+) regulatory T cells, CTLA4(+) inhibitory T cells and interleukin-10, whereas the EAE-evoked upregulation of pro-inflammatory genes in the spinal cord was strongly reduced. The effects were associated with an increase of plasma and cortical endocannabinoids but decreased spinal prostaglandins, the latter likely due to R to S inversion. The promising results suggest potential efficacy of R-flurbiprofen in human MS, and its low toxicity may justify a clinical trial.

Role of the inhibition of oxidative stress and inflammatory mediators in the neuroprotective effects of hydroxytyrosol in rat brain slices subjected to hypoxia reoxygenation

The aim of this study was to analyze the mechanism of the neuroprotective effect of hydroxytyrosol (HT) in an experimental model of hypoxia-reoxygenation in rat brain slices. After reoxygenation the increase in lactate dehydrogenase efflux was inhibited by HT in a concentration-dependent manner and dose-dependent inhibition after oral administration to rats for 7 days (1, 5 and 10 mg/kg per day). Maximum inhibition was 57.4% in vitro and 38.7% ex vivo. Hydroxytyrosol reduced oxidative stress parameters: it inhibited lipid peroxidation and increased enzymatic activities related with the glutathione system both in vitro and after oral administration to rats. The increase in prostaglandin E2 and interleukin 1β after reoxygenation were inhibited after incubation of brain slices with HT and after oral administration. The accumulation of nitric oxide in brain slices was reduced in a concentration-dependent manner. In conclusion, HT exerts a neuroprotective effect in a model of hypoxia-reoxygenation in rat brain slices, both in vitro and after 7 days of oral administration to rats. HT exerts an antioxidant activity and lowered some inflammatory markers in this model.