Design, synthesis and evaluation of 2-(2-oxoethyl)pyrimidine-5-carboxamide derivatives as acetylcholinesterase inhibitors

Progress in the study of anti-Alzheimer's disease activity of pyrimidine-containing bioactive molecules

Pyrimidines are aromatic, heterocyclic organic compounds characterized by a six-membered ring that contains four carbon atoms and two nitrogen atoms. They have been reported to exhibit a variety of biological activities such as antifungal, antiviral, and anti-Parkinsonian effects. Recently, there has been an increased focus on their potential anti-Alzheimer's properties. Several pyrimidine-based drugs and their analogs are currently undergoing various phases of clinical trials, indicating pyrimidine as a promising chemical structure for drug development. Notably, modifications to the pyrimidine structure significantly influence their activity against Alzheimer's disease. For instance, the introduction of heteroatoms into the pyrimidine ring or alternations in the length of the linkage region have been shown to enhance therapeutic efficacy. This review provides a comprehensive overview of pyrimidine derivatives as potential therapeutics for Alzheimer's disease, with a focus on structure-activity relationship (SAR) studies, design strategies, and binding mechanisms. These insights could pave the way for the development of more effective anti-Alzheimer's medications.

Discovery and structure - activity relationships of 2,4,5-trimethoxyphenyl pyrimidine derivatives as selective D5 receptor partial agonists

Dopamine receptors are therapeutic targets for the treatment of various neurological and psychiatric disorders, including Parkinson's and Alzheimer's. Previously, PF-06649751 (tavapadon), PF-2562 and PW0464 have been discovered as potent and selective G protein-biased D1/D5 receptor agonists with optimal pharmacokinetic properties. However, no selective D5R agonist has been reported yet. In this context, we designed and synthesized forty non-catecholamines-based pyrimidine derivatives and identified four pyrimidine derivatives as selective D5R partial agonists. Using cAMP-based GloSensor assay in transiently transfected HEK293T cells with human D1 or D5 receptors, we discovered that compound 5c (4-(4-bromophenyl)-6-(2,4,5-trimethoxyphenyl)pyrimidin-2-amine) exhibited modest D5R agonist activity. This leads us to explore various modifications of this scaffold to improve the D5 agonist potency and efficacy. Using molecular docking, and rational design followed by their evaluation at D1 and D5 receptors for agonist activity, we identified three new derivatives, 5j, 5h, and 5e. The most potent compound of this series 5j (4-(4-iodophenyl)-6-(2,4,5-trimethoxyphenyl)pyrimidin-2-amine), exhibited EC50 of 269.7 ± 6.6 nM. Mice microsomal stability studies revealed that 5j is quite stable (>70 % at 1 hr). Furthermore, pharmacokinetic analysis of 5j (20 mg/kg, p.o) in C57BL/6j mice showed that 5j is readily absorbed via oral route of dosing and also enters into the brain (plasma Tmax: 1 h, Cmax: 51.10 ± 13.51 ng/ml; Brain Tmax: 0.5 h, Cmax: 22.54 ± 4.08 ng/ml). We further determined the in-vivo effect of 5j on cognition in scopolamine-induced amnesia in C57BL/6j mice. We observed that 5j (10 mg/kg, p.o) alleviated scopolamine-induced impairment in short-term memory and social recognition, which were blocked by D1/D5 antagonist SCH23390 (0.1 mg/kg, i.p.). Furthermore, 5j did not exhibit any cytotoxicity (up to 10 µM) or in vivo acute toxicity up to 200 mg/kg (p.o). These results strongly suggest that 5j could be further developed for treating neurological disorders wherein the D5 receptors play pivotal roles.

Sulfonyl thiourea derivatives from 2-aminodiarylpyrimidines: In vitro and in silico evaluation as potential carbonic anhydrase I, II, IX, and XII inhibitors

A series of synthesized sulfonyl thiourea derivatives (7a-o) of substituted 2-amino-4,6-diarylpyrimidines (4a-o) exhibited the remarkable inhibitory activity against some the human carbonic anhydrases (hCAs), including hCA I, II, IX, and XII isoforms. The inhibitory efficacy of synthesized sulfonyl thiourea derivatives were experimentally validated by in vitro enzymatic assays. 7a (KI  = 46.14 nM), 7j (KI  = 48.92 nM), and 7m (KI  = 62.59 nM) (for isoform hCA I); 7f (KI  = 42.72 nM), 7i (KI  = 40.98 nM), and 7j (KI  = 33.40 nM) (for isoform hCA II); 7j (KI  = 228.5 nM), 7m (KI  = 195.4 nM), and 7n (KI  = 210.1 nM) (for isoform hCA IX); 7l (KI  = 116.9 nM), 7m (KI  = 118.8 nM), and 7n (KI  = 147.2 nM) (for isoform hCA XII) in comparison with KI values of 452.1, 327.3, 437.2, and 338.9 nM, respectively, of the standard drug AAZ. These compounds also had significantly more potent inhibitory action against cytosolic isoform hCA I and tumor-associated isoforms hCA IX and hCA XII. Furthermore, the potential inhibitory compounds were subjected to in silico screening for molecular docking and molecular dynamics simulations. The results of in vitro and in silico studies revealed that compounds 7a, 7j, and 7m were the most promising derivatives in this series due to their significant effects on studied hCA I, II, IX, and XII isoforms, respectively. The results showed that the sulfonyl thiourea moiety was accommodated deeply in the active site and interacted with the zinc ion in the receptors.

Novel Substituted Pyrimidine Derivatives as Potential Anti-Alzheimer's Agents: Synthesis, Biological, and Molecular Docking Studies

The most frequent type of age-related dementia is Alzheimer's disease. To discover novel therapeutic agents for Alzheimer's disease, a series of substituted pyrimidine derivatives were synthesized and evaluated for anti-Alzheimer's activity. All the synthesized compounds were validated by 1HNMR, 13CNMR, and HRMS to assess the structural conformance of the newly synthesized compounds. The synthesized compounds were then evaluated for their in vivo acute toxicity study. Evaluation of acute toxicity showed that none of the synthesized compounds showed toxicity up to 1000 mg/kg. After in vivo acute toxicity studies, the compounds were subjected to behavioral and biochemical studies. Compound N4-(4-chlorophenyl)-N2-(2-(piperidin-1-yl)ethyl)pyrimidine-2,4-diamine 5b (SP-2) displayed an excellent anti-Alzheimer's profile, while the rest of the compounds showed satisfactory results in comparison to donepezil. Docking studies confirmed the results obtained through in vivo experiments and showed that 5b (SP-2) showed a similar interaction to that of donepezil. Further, in silico molecular property predictions showed that 5b (SP-2) possesses favorable drug-likeness and ADME properties for CNS activity. These results implied that 5b could serve as an appropriate lead molecule for the development of anti-Alzheimer's agent.

Design, synthesis, extra-precision docking, and molecular dynamics simulation studies of pyrrolidin-2-one derivatives as potential acetylcholinesterase inhibitors

Inhibition of acetylcholinesterase (AChE) has been widely explored to develop novel molecules for management of Alzheimer's disease. In past research finding reported molecule 3-(4-(4-fluorobenzoyl)piperidin-1-yl)-1-(4-methoxybenzyl)pyrrolidin-2-one displayed a spectrum of anti-Alzheimer's properties herein, we report a library of 18 novel molecules that were rationally designed and synthesized employing known literature to mimic and explore the novel chemical space around the lead compound 6e and donepezil. All the compounds were docked in extra-precision mode with AChE (PDB ID 4EY7) using the Glide module. Molecular dynamics (MD) simulation studies were carried out for 100 ns along with MM-PBSA studies of the trajectory frames generated post-MD simulations. Docking and MD simulation studies suggested that the synthesized compounds showed a good binding affinity with AChE. and might form stable complexes. 3-(4-(benzyl(methyl)amino)piperidin-1-yl)-1-(3,4-dimethoxybenzyl)pyrrolidin-2-one (14a; docking score: -18.59) and 1-(3,4-dimethoxybenzyl)-3-(4-(methyl(thiazol-2-ylmethyl)amino)piperidin-1-yl)pyrrolidin-2-one (14d; docking score: -18.057) showed higher docking score than donepezil (docking score: -17.257) while most of the compounds had docking score >-10.0. ADMET study predicted these compounds to be CNS active and most of the compounds were drug-like molecules with no HERG blockade and good to excellent oral absorption. We developed an atom-based 3 D-QSAR model with R^2 and Q^2 values of 0.9639 and 0.8779 to predict the activity of the synthesized compounds. The model predicted these compounds to be potent AChE inhibitors with IC₅₀ values in the lower micromolar range. Based on the in silico findings, we report these newly synthesized compounds 3-(4-(benzyl(methyl)amino)piperidin-1-yl)-1-(3,4-dimethoxybenzyl)pyrrolidin-2-one (14a) and 7-(2,6-difluorobenzyl)-2-(4-methoxybenzyl)-2,7-diazaspiro[4.5]decan-1-one (20 b) as potential AChE inhibitors.Communicated by Ramaswamy H. Sarma.