A Next Generation Synthesis of BACE1 Inhibitor Verubecestat (MK-8931)

Pharmacophore-based virtual screening of commercial databases against β-secretase 1 for drug development against Alzheimer's disease

β-secretase 1, one of the most important proteins, is an aspartate protease. This membrane-associated protein is used for treating Alzheimer's disease (AD). Several inhibitors have been pursued against β-secretase 1, but they still have not resulted effectively. Virtual screening based on pharmacophores has been shown to be useful for lead optimization and hit identification in the preliminary phase of developing a new drug. Here, we screen the commercially available databases to find the hits against β-secretase 1 for drug discovery against AD. Virtual screening for 200,000 compounds was done using the database from the Vitas-M Laboratory. The phase screen score was utilized to assess the screened hits. Molecular docking was performed on compounds with phase scores >1.9. According to the study, the 66H ligand of the crystal structure has the maximum performance against β-secretase 1. The redocking of the co-crystal ligand showed that the docked ligand was seamlessly united with the crystal structure. The reference complex had three hydrogen bonds with Asp93, Asp289, and Gly291; one van der Waals interaction with Gly74; and three hydrophobic interactions. After equilibration, the RMSD of the reference compound sustained a value of ∼1.5 Å until 30 ns and then boosted to 2.5 Å. On comparison, the RMSD of the S1 complex steadily increased to ∼2.5 Å at 15 ns, displayed slight aberrations at approximately ∼2.5-3 Å until 80 ns, and then achieved steadiness toward the end of the simulation. The arrangements of proteins stayed condensed during the mockup when bonded to these complexes as stable Rg values showed. Furthermore, the MM/GBSA technique was employed to analyze both compounds' total binding free energies (ΔGtotal). Our research study provides a new understanding of using 66H as anti-β-secretase 1 for drug development against AD.

Diversification of Pharmaceutical Manufacturing Processes: Taking the Plunge into the Non-PGM Catalyst Pool

Recent global events have led to the cost of platinum group metals (PGMs) reaching unprecedented heights. Many chemical companies are therefore starting to seriously consider and evaluate if and where they can substitute PGMs for non-PGMs in their catalytic processes. This review covers recent highly relevant applications of non-PGM catalysts in the modern pharmaceutical industry. By highlighting these selected successful examples of non-PGM-catalyzed processes from the literature, we hope to emphasize the enormous potential of non-PGM catalysis and inspire further development within this field to enable this technology to progress toward manufacturing processes. We also present some historical contexts and review the perceived advantages and challenges of implementing non-PGM catalysts in the pharmaceutical manufacturing environment.

1,3-Migrative Ring Expansion of Spiroindolenines to Azepino[3,4-b]indoles

We serendipitously found an unprecedented 5-to-7-membered ring expansion of 2-alkylspiroindolenines to azepinoindoles mediated by n-tetrabutylammonium fluoride. The starting materials can be easily prepared by the hypoiodite-catalyzed oxidative dearomative spirocyclization of indole derivatives. Mildly basic conditions and electron-deficient protecting groups for the amines were found to be crucial to promoting chemoselective reactions. Moreover, the ring expansion of aniline-derived spiroindolenines proceeds smoothly under much milder conditions using only a catalytic amount of cesium carbonate.

Unravelling the molecular basis of AM-6494 high potency at BACE1 in Alzheimer's disease: an integrated dynamic interaction investigation

β-amyloid precursor protein cleaving enzyme1 (BACE1) has prominently been an important drug design target implicated in Alzheimer's disease pathway. The failure rate of most of the already tested drugs at different clinical phases remains a major concern. Recently, AM-6494 was reported as a novel potent, highly selective, and orally effective inhibitor against BACE1. AM-6494 displayed no alteration of skin/fur colour in animal studies, an adverse effect common to previous BACE1 inhibitors. However, the atomistic molecular mechanism of BACE1 inhibition by AM-6494 remains unclear. To elucidate the binding mechanism of AM-6494 relative to umibecestat (CNP-520) as well as the structural changes when bound to BACE1, advanced computational techniques such as accelerated MD simulation and principal component analysis have been utilised. The results demonstrated higher binding affinity of AM-6494 at BACE1 with van der Waals as dominant energy contributor compared to umibecestat. Conformational monitoring of the β-hairpin flap covering the active site revealed an effective flap closure when bound with AM-6494 compared to CNP-520, which predominantly alternates between semi-open and closed conformations. The observed effective flap closure of AM-6494 explains its higher inhibitory power towards BACE1. Besides the catalytic Asp32/228 dyad, Tyr14, Leu30, Tyr71 and Gly230 represent critical residues in the potency of these inhibitors at BACE1 binding interface. The findings highlighted in this research provide a basis to explain AM-6494 high inhibitory potency and might assist in the design of new inhibitors with improved selectivity and potency for BACE1.

Computational modelling of potent β-secretase (BACE1) inhibitors towards Alzheimer's disease treatment

Researchers have identified the β-amyloid precursor protein cleaving enzyme 1 (BACE1) in the multifactorial pathway of Alzheimer's disease (AD) as a drug target. The design and development of molecules to inhibit BACE1 as a potential cure for AD thus remained significant. Herein, we simulated two potent BACE1 inhibitors (AM-6494 and CNP-520) to understand their binding affinity at the atomistic level. AM-6494 is a newly reported potent BACE1 inhibitor with an IC₅₀ value of 0.4 nM in vivo and now picked for preclinical considerations. Umibecestat (CNP-520), which was discontinued at human trials lately, was considered to enable a reasonable evaluation of our results. Using density functional theory (DFT) and Our Own N-layered Integrated molecular Orbital and Molecular Mechanics (ONIOM), we achieved the aim of this investigation. These computational approaches enabled the prediction of the electronic properties of AM-6494 and CNP-520 plus their binding energies when complexed with BACE1. For AM-6494 and CNP-520 interaction with protonated BACE1, the ONIOM calculation gave binding free energy of -62.849 and -33.463 kcal/mol, respectively. In the unprotonated model, we observed binding free energy of -59.758 kcal/mol in AM-6494. Taken together thermochemistry of the process and molecular interaction plot, AM-6494 is more favourable than CNP-520 towards the inhibition of BACE1. The protonated model gave slightly better binding energy than the unprotonated form. However, both models could sufficiently describe ligand binding to BACE1 at the atomistic level. Understanding the detailed molecular interaction of these inhibitors could serve as a basis for pharmacophore exploration towards improved inhibitor design.

The chemistry and biology of guanidine secondary metabolites

Covering: 2017-2019Guanidine natural products isolated from microorganisms, marine invertebrates and terrestrial plants, amphibians and spiders, represented by non-ribosomal peptides, guanidine-bearing polyketides, alkaloids, terpenoids and shikimic acid derived, are the subject of this review. The topics include the discovery of new metabolites, total synthesis of natural guanidine compounds, biological activity and mechanism-of-action, biosynthesis and ecological functions.

Acute exercise and brain BACE1 protein content: a time course study

Obesity and insulin resistance are risk factors in the development of neurodegenerative disorders. Previous work suggests that one acute bout of exercise may have beneficial neuro-protective effects in obese mice. The rate limiting enzyme in the production of amyloid-beta peptides, BACE1, was reduced in the prefrontal cortex 2 h post-exercise, however if these effects remain over time is unknown. We aimed to determine how long exercise-induced alterations persist in the prefrontal cortex and hippocampus following a single exercise bout. Male C57BL/6J mice were fed either a low (LFD, 10% kcals from lard) or a high fat diet (HFD, 60% kcals from lard) for 7 weeks. HFD mice then underwent an acute bout of treadmill running (15 m/min, 5% incline, 120 min) followed by 2-, 8-, or 24-h of recovery. The HFD increased body mass (LFD 27.8 ± 1.05 vs. HFD 41.7 ± 0.60 g; P < 0.05) and glucose intolerance (AUC LFD 63.27 ± 4.5 vs. HFD 128.9 ± 4.6; P < 0.05). Prefrontal cortex BACE1 content was reduced 2- and 8-h post-exercise compared to sedentary HFD mice, however BACE1 protein content at 24 h was not different. Hippocampal BACE1 content was reduced 8- and 24-h post-exercise. Compared to the LFD, the HFD had higher prefrontal cortex phosphorylation of p38, JNK, and AMPK, indicative of increased neuronal stress. Post-exercise prefrontal cortex p38 and JNK phosphorylation were no different between the HFD or LFD groups, while ERK phosphorylation was significantly reduced by 24 h. The HFD increased JNK phosphorylation in the hippocampus. These results demonstrate the direct and potent effects of exercise on reducing BACE1 prefrontal cortex and hippocampal content. However the reduction in prefrontal cortex BACE1 content is short lived.

Drug Development for Alzheimer's Disease: Microglia Induced Neuroinflammation as a Target?

Alzheimer's disease (AD) is one of the most common causes of dementia. Its pathogenesis is characterized by the aggregation of the amyloid-β (Aβ) protein in senile plaques and the hyperphosphorylated tau protein in neurofibrillary tangles in the brain. Current medications for AD can provide temporary help with the memory symptoms and other cognitive changes of patients, however, they are not able to stop or reverse the progression of AD. New medication discovery and the development of a cure for AD is urgently in need. In this review, we summarized drugs for AD treatments and their recent updates, and discussed the potential of microglia induced neuroinflammation as a target for anti-AD drug development.

Palladium-Catalyzed Enantioselective Synthesis of Cyclic Sulfamidates and Application to a Synthesis of Verubecestat

An enantioselective arylation reaction catalyzed by palladium complexed with substituted phosphinooxazoline (PHOX) ligands is described. Aza-quaternary stereocenters are readily accessible through the arylation reaction between cyclic iminosulfates and a wide variety of arylboronic acids, including electron-poor and ortho-substituted arylboronic acids. This reaction was applied to the preparation of verubecestat, which is currently undergoing clinical evaluation for the treatment of Alzheimer's disease.