An Efficient Synthesis of bi-Aryl Pyrimidine Heterocycles: Potential New Drug Candidates to Treat Alzheimer's Disease

Design and synthesis of new indole drug candidates to treat Alzheimer's disease and targeting neuro-inflammation using a multi-target-directed ligand (MTDL) strategy

A novel series of indole-based compounds was designed, synthesised, and evaluated as anti-Alzheimer’s and anti-neuroinflammatory agents. The designed compounds were in vitro evaluated for their AChE and BuChE inhibitory activities. The obtained results revealed that compound 3c had higher selectivity for AChE than BuChE, while, 4a, 4b, and 4d showed selectivity for BuChE over AChE. Compounds 5b, 6b, 7c, and 10b exerted dual AChE/BuChE inhibitory activities at nanomolar range. Compounds 5b and 6b had the ability to inhibit the self-induced Aβ amyloid aggregation. Different anti-inflammatory mediators (NO, COX-2, IL-1β, and TNF-α) were assessed for compounds 5b and 6b. Cytotoxic effect of 5b and 6b against human neuroblastoma (SH-SY5Y) and normal hepatic (THLE2) cell lines was screened in vitro. Molecular docking study inside rhAChE and hBuChE active sites, drug-likeness, and ADMET prediction were performed.

Inhibitory potential of nitrogen, oxygen and sulfur containing heterocyclic scaffolds against acetylcholinesterase and butyrylcholinesterase

Heterocycles are the key structures in organic chemistry owing to their immense applications in the biological, chemical, and pharmaceutical fields. Heterocyclic compounds perform various noteworthy functions in nature, medication, innovation etc. Most frequently, pure nitrogen heterocycles or various positional combinations of nitrogen, oxygen, and sulfur atoms in five or six-membered rings can be found. Inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes is a popular strategy for the management of numerous mental diseases. In this context, cholinesterase inhibitors are utilized to relieve the symptoms of neurological illnesses like dementia and Alzheimer's disease (AD). The present review focuses on various heterocyclic scaffolds and their role in designing and developing new potential AChE and BChE inhibitors to treat AD. Moreover, a detailed structure-activity relationship (SAR) has been established for the future discovery of novel drugs for the treatment of AD. Most of the heterocyclic motifs have been used in the design of new potent cholinesterase inhibitors. In this regard, this review is an endeavor to summarize the biological and chemical studies over the past decade (2010-2022) describing the pursuit of new N, O and S containing heterocycles which can offer a rich supply of promising AChE and BChE inhibitory activities.

Design and synthesis of new quinoline derivatives as selective C-RAF kinase inhibitors with potent anticancer activity

This article describes the design, synthesis, and biological screening of a new series of diarylurea and diarylamide derivatives including quinoline core armed with dimethylamino or morpholino side chain. Fifteen target compounds were selected by the National Cancer Institute (NCI, USA) for in vitro antiproliferative screening against a panel of 60 cancer cell lines of nine cancer types. Compounds 1j-l showed the highest mean inhibition percentage values over the 60-cell line panel at 10 μM with broad-spectrum antiproliferative activity. Subsequently, compounds 1j-l were subjected to a dose-response study to measure their GI₅₀ and total growth inhibition (TGI) values against the cell lines. Three of the tested molecules exerted higher potency against most of the cell lines than the reference drug, sorafenib. Compound 1l indicated a higher potency than sorafenib against 53 of tested cancer cell lines. Compounds 1j-l demonstrated promising selectivity against cancer cells than normal cells. Moreover, compound 1l induced apoptosis and necrosis in RPMI-8226 cell line in a dose-dependent manner. In addition, compounds 1j-l were tested against C-RAF kinase as a potential molecular target. The three compounds showed high potency, and the most potent C-RAF kinase inhibitor was compound 1j with an IC₅₀ value of 0.067 μM. In addition, Compounds 1j-l were further tested at 1 μM concentration against a panel of another twelve kinases and they showed a high selectivity for C-RAF kinase. Molecular modeling studies were performed to illuminate on the putative binding interactions of these motifs in the active site of C-RAF kinase. Additional studies were conducted to measure aqueous solubility, partition coefficient, and Caco-2 permeability of the most promising derivatives.

Dimethoxyindoles based thiosemicarbazones as multi-target agents; synthesis, crystal interactions, biological activity and molecular modeling

Alzheimer's disease (AD) is known as one of the most devastating neurodegenerative disease diagnosed for the old-aged people and cholinesterase inhibitors (ChEI) can be used as an effective palliative treatment for AD. A range of novel monomeric and dimeric indole based thiosemicarbazone derivatives 17-28 was synthesized in order to target cholinesterases (ChE). Biological importance of the targeted compounds 17-28 was investigated by employing the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes along with three different antioxidant property determination assays, namely DPPH free radical scavenging, ABTS cationic radical decolarization, and CUPRAC cupric reducing antioxidant capacity. The compounds 18 and 19 displayed the best inhibitor activity against BChE with IC₅₀ values of 7.42 and 1.95 μM, respectively. The antioxidant potentials were found to be moderate for DPPH and ABTS assays and the compounds 28 and 18 were the most potent candidates for both antioxidant assays. Cupric reducing capacity was the most promising assay and the compounds 25, 26 and 28 provided better inhibition values than all the standards. Further binding mode and affinity studies performed by molecular docking and molecular dynamics simulations. Accordingly, the compound 19 is the most plausible candidate that can compete with galantamine (GNT), a common pharmaceutics targeting both cholinesterase enzymes.

Synthesis and biological evaluation of 2-(4-alkoxy-3-cyano)phenylpyrimidine derivatives with 4-amino or 4-hydroxy as a pharmacophore element binding with xanthine oxidase active site

Xanthine oxidase is the rate-limiting enzyme critical for the synthesis of uric acid, and therefore xanthine oxidase inhibitors are considered as one of the promising therapies for hyperuricemia and gout. In our previous study, series of 2-(4-alkoxy-3-cyano)phenyl-6-oxo-1,6-dihydropyrimidine-5-carboxylic acids and 2-(4-alkoxy-3-cyano)phenyl-6-imino-1,6-dihydropyrimidine-5-carboxylic acids were synthesized that presented excellent in vitro xanthine oxidase inhibitory potency. Interestingly, molecular docking studies revealed that the interaction behavior of these compounds with xanthine oxidase was changed after the conversion from a hydroxy group to amine group. To further investigate the structure-activity relationships of these pyrimidine-containing xanthine oxidase inhibitors and explore the contribution of amino or hydroxy group on xanthine oxidase inhibitory potency, several 2-phenylpyrimidine derivatives with amino or hydroxy functional group were designed and synthesized. Thereafter, the structure-activity research and molecular modeling study proved that hydroxy and amino groups could be used as pharmacophore elements for the design of 2-phenylpyrimidines xanthine oxidase inhibitors. Particularly, the optimized compound, 2-(3-cyano-4-isopentoxy)phenylpyrimidine-4-ol, emerged the strongest xanthine oxidase inhibitor potency, with an IC₅₀ value of 0.046 µM, which was approximately 120-fold more potent than that of allopurinol (IC₅₀ = 5.462 µM). Additionally, Lineweaver-Burk plot analysis revealed that the optimized compound acted as a mixed-type inhibitor. Furthermore, the in vivo hypouricemic effect of the optimized compound was investigated in a hyperuricemia rat model induced by potassium oxonate, and the results showed that the optimized compound could effectively reduce serum uric acid levels at an oral dose of 30 mg/kg.

Naturally Inspired Pyrimidines Analogues for Alzheimer's Disease

Alzheimer's disease (AD) is a multifarious and developing neurodegenerative disorder. The treatment of AD is still a challenge and availability of drug therapy on the basis of symptoms is not up to the mark. In the context of existence, which is getting worse for the human brain, it is necessary to take care of all critical measures. The disease is caused due to multidirectional pathology of the body, which demands the multi-target-directed ligand (MTDL) approach. This gives hope for new drugs for AD, summarized here in with the pyrimidine based natural product inspired molecule as a lead. The review is sufficient in providing a list of chemical ingredients of the plant to cure AD and screen them against various potential targets of AD. The synthesis of a highly functionalized scaffold in one step in a single pot without isolating the intermediate is a challenging task. In few examples, we have highlighted the importance of this kind of reaction, generally known as multi-component reaction. Multi-component is a widely accepted technique by the drug discovery people due to its high atom economy. It reduces multi-step process to a one-step process, therefore the compounds library can be made in minimum time and cost. This review has highlighted the importance of multicomponent reactions by giving the example of active scaffolds of pyrimidine/fused pyrimidines. This would bring importance to the fast as well as smart synthesis of bio-relevant molecules.

Microwave Assisted Reactions of Azaheterocycles Formedicinal Chemistry Applications

Microwave (MW) assisted reactions have became a powerful tool in azaheterocycles chemistry during the last decades. Five and six membered ring azaheterocycles are privileged scaffolds in modern medicinal chemistry possessing a large variety of biological activity. This review is focused on the recent relevant advances in the MW assisted reactions applied to azaheterocyclic derivatives and their medicinal chemistry applications from the last five years. The review is divided according to the main series of azaheterocycles, more precisely 5- and 6-membered ring azaheterocycles (with one, two, and more heteroatoms) and their fused analogues. In each case, the reaction pathways, the advantages of using MW, and considerations concerning biological activity of the obtained products were briefly presented.

Organocatalyzed Solvent Free and Efficient Synthesis of 2,4,5-Trisubstituted Imidazoles as Potential Acetylcholinesterase Inhibitors for Alzheimer's Disease

The catalytic potential of pyridine-2-carboxlic acid has been evaluated for efficient, green and solvent free synthesis of 2,4,5-trisubstituted imidazole derivatives 3a-3m. The compounds 3a-3m were synthesized by one pot condensation reaction of substituted aromatic aldehydes, benzil, and ammonium acetate in good to excellent yields (74-96 %). To explore the potential of these compounds against Alzheimer's disease, their inhibitory activities against acetylcholinesterase (AChE) were evaluated. In this series of compounds, compound 3m, bearing one ethoxy and a hydroxy group on the phenyl ring on 2,4,5-trisubstituted imidazoles, proved to be a potent AChE inhibitor (102.56±0.14). Structure-activity relationship (SAR) of these compounds was developed. Molecular dockings were carried out for the compounds 3m, 3e, 3k, 3c, 3a, 3d, 3j, and 3f in order to further investigate the binding mechanism. The inhibitor molecule was molecularly docked with acetylcholinesterase to further study its binding mechanism. The amino group of the compound 3m forms an H-bond with the oxygen atom of the residue (i. e., THR121) which has a bond length of 3.051 Å.

Development of benzochalcone derivatives as selective CYP1B1 inhibitors and anticancer agents

A series of benzochalcone derivatives have been synthesized and evaluated for CYP1 inhibitory activity and cytotoxic properties against wild type cell lines (MCF-7 and MDA-MB-231) and drug resistant cell lines (LCC6/P-gp and MCF-7/1B1). All of these compounds were found to have selective inhibition towards CYP1B1 and the most potent two possessed single-digit nanomolar CYP1B1 potency. In addition, some of them showed promising cytotoxic activities not only against wild type cells, but also against drug resistant cells at low micromolar concentrations. More importantly, these multi-functional compounds may surmount drug-drug interactions that frequently occur during the combination of CYP1B1/P-gp inhibitors and anticancer drugs to overcome drug resistance. This study may provide a good starting point for the further development of more potent multi-functional agents with CYP1B1 inhibitory activity and cytotoxic potency in cancer prevention and treatment.

Pharmaceutical and medicinal significance of sulfur (SVI)-Containing motifs for drug discovery: A critical review

Sulfur (S^VI) based moieties, especially, the sulfonyl or sulfonamide based analogues have showed a variety of pharmacological properties, and its derivatives propose a high degree of structural diversity that has established useful for the finding of new therapeutic agents. The developments of new less toxic, low cost and highly active sulfonamides containing analogues are hot research topics in medicinal chemistry. Currently, more than 150 FDA approved Sulfur (S^VI)-based drugs are available in the market, and they are widely used to treat various types of diseases with therapeutic power. This comprehensive review highlights the recent developments of sulfonyl or sulfonamides based compounds in huge range of therapeutic applications such as antimicrobial, anti-inflammatory, antiviral, anticonvulsant, antitubercular, antidiabetic, antileishmanial, carbonic anhydrase, antimalarial, anticancer and other medicinal agents. We believe that, this review article is useful to inspire new ideas for structural design and developments of less toxic and powerful Sulfur (S^VI) based drugs against the numerous death-causing diseases.