Discovery and Optimization of Triazolopyrimidinone Derivatives as Selective NLRP3 Inflammasome Inhibitors.

The NLRP3 inflammasome is a multiprotein complex that facilitates activation and release of the proinflammatory cytokines interleukin-1ß (IL-1ß) and IL-18 in response to infection or endogenous stimuli. It can be inappropriately activated by a range of danger signals resulting in chronic, low-grade inflammation underlying a multitude of diseases, such as Alzheimer's disease, Parkinson's disease, osteoarthritis, and gout. The discovery of potent and specific NLRP3 inhibitors could reduce the burden of several common morbidities. In this study, we identified a weakly potent triazolopyrimidone hit (1) following an in silico modeling exercise. This was optimized to furnish potent and selective small molecule NLRP3 inflammasome inhibitors. Compounds such as NDT-30805 could be useful tool molecules for a scaffold-hopping or pharmacophore generation project or used as leads toward the development of clinical candidates.

ONO-8590580, a Novel GABAAα5 Negative Allosteric Modulator Enhances Long-Term Potentiation and Improves Cognitive Deficits in Preclinical Models.

GABAA receptors containing α5 subunits (GABAAα5) are highly expressed in the hippocampus and negatively involved in memory processing, as shown by the fact that GABAAα5-deficient mice show higher hippocampus-dependent performance than wild-type mice. Accordingly, small-molecule GABAAα5 negative allosteric modulators (NAMs) are known to enhance spatial learning and memory in rodents. Here we introduce a new, orally available GABAAα5 NAM that improves hippocampal functions. ONO-8590580 [1-(cyclopropylmethyl)-5-fluoro-4-methyl-N-[5-(1-methyl-1H-imidazol-4-yl)-2-pyridinyl]-1H-benzimidazol-6-amine] binds to the benzodiazepine binding sites on recombinant human α5-containing GABAA receptors with a Ki of 7.9 nM, and showed functionally selective GABAAα5 NAM activity for GABA-induced Cl- channel activity with a maximum 44.4% inhibition and an EC50 of 1.1 nM. In rat hippocampal slices, tetanus-induced long-term potentiation of CA1 synapse response was significantly augmented in the presence of 300 nM ONO-8590580. Orally administered ONO-8590580 (1-20 mg/kg) dose-dependently occupied hippocampal GABAAα5 in a range of 40%-90% at 1 hour after intake. In the rat passive avoidance test, ONO-8590580 (3-20 mg/kg, by mouth) significantly prevented (+)-MK-801 hydrogen maleate (MK-801)-induced memory deficit. In addition, ONO-8590580 (20 mg/kg, p.o.) was also effective in improving the cognitive deficit induced by scopolamine and MK-801 in the rat eight-arm radial maze test with equal or greater activity than 0.5 mg/kg donepezil. No anxiogenic-like or proconvulsant effect was associated with ONO-8590580 at 20 mg/kg p.o. in the elevated plus maze test or pentylenetetrazole-induced seizure test, respectively. In sum, ONO-8590580 is a novel GABAAα5 NAM that enhances hippocampal memory function without an anxiogenic or proconvulsant risk.

A formal total synthesis of (+)-apicularen A: base-induced conversion of apicularen-derived intermediates into salicylihalamide-like products.

A synthesis of apicularen precursor (-)-6 in 18 steps from D-glucal is reported. As (+)-6 has been converted into the potent, naturally occurring salicylate anti-cancer agent, (-)-apicularen A in 8 steps, this study constitutes a formal total synthesis of (+)-apicularen A. Key steps in the synthetic route include: (i) useful D-glucal elaboration processes, (ii) organometallic displacements at carbohydrate C-6 triflates using Knochel-type and related functionalised, aromatic Grignard reagents, (iii) stereoselective allyltrimethylsilane-acetal reactions generating C-allyl systems, (iv) stereocontrolled aldehyde allylation processes from both substrate and reagent, and (v) a novel Keck-type macrolactonisation. In addition, preliminary studies are reported in which a procedure has been devised to convert apicularen-derived intermediates into salicylihalamide-like products.