Investigation, scaffold hopping of novel donepezil-based compounds as anti-Alzhiemer's agents: synthesis, in-silico and pharmacological evaluations.

Alzheimer's disease (AD) is a multifaceted neurodegenerative condition. The pathogenesis of AD is highly intricate and the disease is apparent in the aged population ~ 50-70 years old. Even after > 100 years of research, the root origin of AD and its pathogenesis is unclear, complex and multifaceted. Herein, we have designed and synthesized 9 novel molecules with three different heterocyclic scaffolds namely pyrrolidone-2-one, quinoline & indoline-2-one to imitate and explore the novel chemical space around donepezil. The synthesized molecules were evaluated for their potential as anti-Alzheimer's agents through in-vitro and in-vivo studies in appropriate animal models. To further understand their interaction with acetylcholinesterase enzyme (AChE), extra-precision docking, and molecular dynamics simulation studies were carried out. As the number of compounds was limited to thoroughly explore the structure-activity relationship, atom-based 3D-quantitative structure-activity relationships (QSAR) studies were carried out to get more insights. All the designed compounds were found to inhibit AChE with IC50 in the micromolar range. From pyrrolidone-2-one series, 6-chloro-N-(1-(1-(3,4-dimethoxybenzyl)-2-oxopyrrolidin-3-yl)piperidin-4-yl)pyridine-3-sulfonamide (9), 2-(1-benzylpiperidin-4-yl)-6,7-dimethoxy-4-(4-methoxyphenyl)quinoline (18) from quinoline series and N-(1-benzylpiperidin-4-yl)-2-(2-oxoindolin-3-yl)acetamide (23) from indolin-2-one series inhibited AChE with an IC50 value of 0.01 µM. Based on other biochemical studies like lipid peroxidation, reduced glutathione, superoxide dismutase, catalase, nitrite, and behavioural studies (Morris water maze), compound 9 was found to be a potent AChE inhibitor which can be further explored as a lead molecule to design more potent and effective anti-Alzheimer's agents.

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.

Synthesis, characterization, and in silico studies of 1,8-naphthyridine derivatives as potential anti-Parkinson's agents.

1,8-Naphthyridine scaffold is a nitrogen-containing heterocyclic compound known for its versatile biological activities. The structure-activity relationship (SAR) has shown that modification at the 3rd position of the nucleus with various secondary amines enhances the binding efficiency and potency towards the Adenosine receptor (A2A type). In this paper, we have reported some newly synthesized derivatives of 1,8- Naphthyridine, and the prepared compounds were assessed for their potential to constrain A2A receptors through molecular docking. Based on the SAR studies, modifications were done at the 3rd position of the nucleus by incorporating secondary amines. The synthesized compounds were characterized by FT-IR, 1H and 13C NMR. All the synthesized compounds 10a-f and 13a-e showed good binding efficiency towards the A2A receptors and might act as an A2A receptor antagonist, as predicted by in-silico studies. 1-Ethyl-7-methyl-3-(pyrrolidine-1-carbonyl)-1,8-naphthyridine-4(1H)-one (10c) in first series showed the highest docking score of -8.407 and binding energy (MMGBSA dG bind) of -56.60 kcal/mol and N-(4-2-diethylaminoethoxyphenyl)-1-ethyl-7-methyl-4-oxo-1, 4, 4a, 8a- tetrahydro-1,8-naphthyridine-3-carboxamide (13b) showed the highest docking score of -8.562 and free binding energy (MMGBSA dG bind) score of -64.13 kcal/mol which was comparable to the bound ligand. MD simulations study also suggested that compounds 10c and 13b would form stable complex human A2A receptor. These findings need to be validated by further in vitro assays.Communicated by Ramaswamy H. Sarma.

Elucidating the Drug Repurposing Spectra of COVID-19 with its Analogues SARS and MERS.

Corona Virus Disease-2019 (COVID-19), caused by the SARS CoV-2 virus, has been announced as a pandemic by the World Health Organization. COVID-19 has affected people globally, infecting more than 39.8 million people and claiming up to 1.11 million lives, yet there is no effective treatment strategy to cure this disease. As vaccine development is a time-consuming process, currently, efforts are being made to develop alternative plans for the timely and effective management of this disease. Drug repurposing always fascinated researchers and can be utilized as the most acceptable alternative to develop the therapeutics for COVID-19 using the pre-approved drugs. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has shown resemblance with distinctive enzyme targets, such as 3CLpro/Mpro, RdRp, Cathepsin L, and TMPRSS2 present in SARS CoV and MERS CoV. Therefore, the drugs that have shown efficacy in these viruses can also be used for the treatment of COVID-19. This review focuses on why repurposing could provide a better alternative in COVID- 19 treatment. The similarity in the structure and progression of infection of SARS CoV and MERS viruses offers a direction and validation to evaluate the drugs approved for SARS and MERS against COVID-19. It has been indicated that multiple therapeutic options that demonstrate efficacy against SARS CoV 2 are available to mitigate the potential emergence of COVID-19 infection.