A novel phenoxy thiophene sulphonamide molecule protects against glutamate evoked oxidative injury in a neuronal cell model

Background: Glutamate is one of the major neurotransmitters in the central nervous system. It is a potent neurotoxin capable of neuronal destruction through numerous signal pathways when present in high concentration. Glutamate-evoked excitotoxicity has been implicated in the etiology of many neurodegenerative diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), and ischemic stroke. Increasing evidence has shown that reactive oxygen species (ROS) provoked by glutamate-linked oxidative stress plays a crucial role in the pathogenesis of these disorders. We previously reported the discovery of an aryl thiophene compound, 4-chloro-N- (naphthalen-1-ylmethyl)-5-(3-(piperazin-1-yl)phenoxy)thiophene-2-sulfonamide (B355252) from a proprietary library of small molecules. We showed that this compound was capable of potentiating nerve growth factor (NGF)-primed neurite outgrowth in neuronal cell models in a low NGF environment. In the present study we investigated the neuroprotective effects and signaling pathways of B355252 on glutamate-evoked excitotoxicity in HT-22, a murine hippocampal neuronal cell line. Results: Glutamate significantly decreased HT-22 neuronal cell viability in a concentration-dependent manner as measured by the MTT assay. Co-treatment with 2, 4, and 8 μM B355252 protected against cell death caused by glutamate-induced toxicity by 9.1% (p<0.01), 26.0% (p<0.001), and 61.9% (p<0.001) respectively, compared to glutamate-treated control group. B355252 at a concentration of 8 μM fully rescued HT-22 from the neurototoxic effects of glutamate, and by itself increased cell viability by 16% (p<0.001) above untreated control. Glutamate enhanced reduction in glutathione (GSH) synthesis was reversed by 15% (p<0.01) in the presence of B355252. B355252 reduced the expression of apoptosis inducing factor (AIF) by 27%, while the proapoptotic Bcl-2 associated X protein (Bax) was strongly attenuated 3-fold. Glutamate-evoked increase in intracellular calcium (Ca2+) load and subsequent ROS production was inhibited by 71% (p<0.001) and 40% (p