The underlying cause of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disorder, remains unknown. However, there is strong evidence that one pathophysiological mechanism, toxic protein misfolding and/or aggregation, may trigger motor neuron dysfunction and loss. Since the clinical and pathological features of sporadic and familial ALS are indistinguishable, all forms of the disease may be better understood and ultimately treated by studying pathogenesis and therapy in models expressing mutant forms of SOD1. We developed a cellular model in which cell death depended on the expression of G93A-SOD1, a mutant form of superoxide dismutase found in familial ALS patients that produces toxic protein aggregates. This cellular model was optimized for high throughput screening to identify protective compounds from a >50,000 member chemical library. Three novel chemical scaffolds were selected for further study following screen implementation, counter-screening and secondary testing, including studies with purchased analogs. All three scaffolds blocked SOD1 aggregation in high content screening assays and data on the optimization and further characterization of these compounds will be reported separately. These data suggest that optimization of these chemicals scaffolds may produce therapeutic candidates for ALS patients.

Amyotrophic lateral sclerosis (ALS) is an orphan neurodegenerative disease currently without a cure. The arylsulfanyl pyrazolone (ASP) scaffold was one of the active scaffolds identified in a cell-based high throughput screening assay targeting mutant Cu/Zn superoxide dismutase 1 (SOD1) induced toxicity and aggregation as a marker for ALS. The initial ASP hit compounds were potent and had favorable ADME properties but had poor microsomal and plasma stability. Here, we identify the microsomal metabolite and describe synthesized analogues of these ASP compounds to address the rapid metabolism. Both in vitro potency and pharmacological properties of the ASP scaffold have been dramatically improved via chemical modification to the corresponding sulfone and ether derivatives. One of the ether analogues (13), with superior potency and in vitro pharmacokinetic properties, was tested in vivo for its pharmacokinetic profile, brain penetration, and efficacy in an ALS mouse model. The analogue showed sustained blood and brain levels in vivo and significant activity in the mouse model of ALS, thus validating the new aryloxanyl pyrazolone scaffold as an important novel therapeutic lead for the treatment of this neurodegenerative disorder.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons, leading to muscle weakness, paralysis, and death, most often from respiratory failure. The only FDA approved drug for the treatment of ALS, riluzole, only extends the median survival in patients by 2–3 months. There is an urgent need for novel therapeutic strategies for this devastating disease. Using a high-throughput screening assay targeting an ALS cultured cell model (PC12-G93A-YFP cell line), we previously identified three chemotypes that were neuroprotective. We present a further detailed analysis of one promising scaffold from that group, pyrimidine-2,4,6-triones (PYTs), characterizing a number of PYT analogs using SAR and ADME. The PYT compounds show good potency, superior ADME data, low toxicity, brain penetration, and excellent oral bioavailability. Compounds from this series show 100% efficacy in the protection assay with a good correlation in activity between the protection and protein aggregation assays. The modifications of the PYT scaffold presented here suggest that this chemical structure may be a novel drug candidate scaffold for use in clinical trials in ALS.

Amyotrophic lateral sclerosis (ALS) is a progressive and ultimately fatal neurodegenerative disease. Pyrazolone containing small molecules have shown significant disease attenuating efficacy in cellular and murine models of ALS. Pyrazolone based affinity probes were synthesized to identify high affinity binding partners and ascertain a potential biological mode of action. Probes were confirmed to be neuroprotective in PC12-SOD1G93A cells. PC12-SOD1G93A cell lysates were used for protein pull-down, affinity purification, and subsequent proteomic analysis using LC-MS/MS. Proteomics identified the 26S proteasome regulatory subunit 4 (PSMC1), 26S proteasome regulatory subunit 6B (PSMC4), and T-complex protein 1 (TCP-1) as putative protein targets. Coincubation with appropriate competitors confirmed the authenticity of the proteomics results. Activation of the proteasome by pyrazolones was demonstrated in the absence of exogenous proteasome inhibitor and by restoration of cellular protein degradation of a fluorogenic proteasome substrate in PC12-SOD1G93A cells. Importantly, supplementary studies indicated that these molecules do not induce a heat shock response. We propose that pyrazolones represent a rare class of molecules that enhance proteasomal activation in the absence of a heat shock response and may have therapeutic potential in ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. Currently, there is only one FDA-approved treatment for ALS (riluzole), and that drug only extends life, on average, by 2–3 months. Mutations in Cu/Zn superoxide dismutase (SOD1) are found in familial forms of the disease and have played an important role in the study of ALS pathophysiology. On the basis of their activity in a PC12-G93A-YFP high-throughput screening assay, several bioactive compounds have been identified and classified as cyclohexane-1,3-dione (CHD) derivatives. A concise and efficient synthetic route has been developed to provide diverse CHD analogs. The structural modification of the CHD scaffold led to the discovery of a more potent analog (26) with an EC50 of 700 nM having good pharmacokinetic properties, such as high solubility, low human and mouse metabolic potential, and relatively good plasma stability. It was also found to efficiently penetrate the blood-brain barrier. However, compound 26 did not exhibit any significant life span extension in the ALS mouse model. It was found that, although 26 was active in PC12 cells, it had poor activity in other cell types, including primary cortical neurons, indicating that it can penetrate into the brain, but is not active in neuronal cells, potentially due to poor selective cell penetration. Further structural modification of the CHD scaffold was aimed at improving global cell activity as well as maintaining potency. Two new analogs (71 and 73) were synthesized, which had significantly enhanced cortical neuronal cell permeability, as well as similar potency to that of 26 in the PC12-G93A assay. These CHD analogs are being investigated further as novel therapeutic candidates for ALS.