Synthesis and Evaluation of Novel Pyrazole Ethandiamide Compounds as Inhibitors of Human THP-1 Monocytic Cell Neurotoxicity.

Neuroinflammation and microglia-mediated neurotoxicity contribute to the pathogenesis of a broad range of neurodegenerative diseases; therefore, identifying novel compounds that can suppress adverse activation of glia is an important goal. We have previously identified a class of trisubstituted pyrazoles that possess neuroprotective and anti-inflammatory properties. Here, we describe a second generation of pyrazole analogs that were designed to improve their neuroprotective activity toward neurons under inflammatory conditions. Pyrazolyl oxalamide derivatives were designed to explore the effects of steric and electronic factors. Three in vitro assays were performed to evaluate the compounds' anti-neurotoxic, neuroprotective, and cytotoxic activity using human THP-1, PC-3, and SH-SY5Y cells. Five compounds significantly reduced the neurotoxic secretions from immune-stimulated microglia-like human THP-1 monocytic cells. One of these compounds was also found to protect SH-SY5Y neuronal cells when they were exposed to cytotoxic THP-1 cell supernatants. While one of the analogs was discarded due to its interference with the cell viability assay, most compounds were innocuous to the cultured cells at the concentrations used (1-100 µM). The new compounds reported herein provide a design template for the future development of lead candidates as novel inhibitors of neuroinflammation and neuroprotective drugs.

Pyrazole compound 2-MBAPA as a novel inhibitor of microglial activation and neurotoxicity in vitro and in vivo.

Pyrazole derivatives are well documented to possess anti-inflammatory activity but their effects on microglial activation are unknown. We determined the efficacy of the novel pyrazole compound 2-MBAPA (R/S-(±)-2-Methylbenzylamino 2-oxo-N-[4-cyano-1-phenyl-1H-pyrazol-5-yl] acetamide) on activated microglia under conditions relevant to inflammation in Alzheimer's disease (AD) brain. The compound at a non-toxic concentration inhibited secretion of tumor necrosis factor (TNF)-α by activated human microglia and attenuated toxicity of conditioned medium from activated human microglia towards human SH-SY5Y neuroblastoma cells in vitro. The 2-MBAPA neuroprotection was further demonstrated in vivo using an animal model of AD. The compound inhibited microgliosis, but not astrogliosis, in amyloid-ß peptide (Aß)(1-42)-injected rat brain. 2-MBAPA also diminished neuronal loss in the dentate gyrus caused by Aß(1-42) injection. These results indicate that this novel pyrazole compound confers neuroprotection by inhibiting microglial activation. Therefore, further studies with 2-MBAPA and novel analogues based on this lead compound are warranted in an effort to develop new pharmacological agents that may be useful for slowing down progression of AD and other neuroinflammatory disorders associated with activated microglia.

Synthesis and biological evaluation of novel pyrazole compounds.

A novel dipyrazole ethandiamide compound and acid chloride of pyrazolo[3,4-d]pyrimidine 4(5H)-one were prepared and reacted with a number of nucleophiles. The resultant novel compounds were tested in several in vitro and in vivo assays. Three compounds inhibited the secretion of neurotoxins by human THP-1 monocytic cells at concentrations that were not toxic to these cells. They also partially inhibited both cyclooxygenase-1 and -2 isoforms. In animal studies, two compounds were notable for their anti-inflammatory activity that was comparable to that of the clinically available cyclooxygenase-2 inhibitor celecoxib. Modeling studies by using the molecular operating environment module showed comparable docking scores for the two enantiomers docked in the active site of cyclooxygenase-2.