Potential anti-Alzheimer Agents Research Articles

Recent development and strategies towards target interactions: Synthesis, characterization and in silico analysis of benzimidazole based thiadiazole as potential anti-Alzheimer agents

In the current research study, we aim to design and synthesize highly potent hybrid analogs of benzimidazole derived thiadiazole based Schiff base derivatives which can combat the cholinesterase enzymes (acetylcholinesterase and butyrylcholinesterase) accountable for developing Alzheimer's disease. In this context, we have synthesized 15 analogs of benzimidazole based thiadiazole derivatives, which were subsequently confirmed through spectroscopic techniques including 1H NMR, 13C NMR and HREI-MS. Biological investigation of all the analogs revealed their varied acetylcholinesterase inhibitory potency covering a range between 3.20 ± 0.10 μM to 20.50 ± 0.20 μM as well as butyrylcholinesterase inhibitory potential with a range of 4.30 ± 0.50 μM to 20.70 ± 0.50 μM when compared with the standard drug Donepezil having IC50 = 6.70 ± 0.20 μM for AChE and 7.90 ± 0.10 μM for BuChE. The promising inhibition by the analogs was evaluated in SAR analysis, where analog-1 (IC50 = 3.20 ± 0.10 μM for AChE and 4.30 ± 0.50 μM for BuChE), analog-4 (IC50 = 4.30 ± 0.30 μM for AChE and 5.50 ± 0.20 μM for BuChE) and analog-5 (IC50 = 4.10 ± 0.30 μM for AChE and 4.60 ± 0.40 μM for BuChE) were found as the lead candidates. Moreover, molecular docking and ADME analysis were conducted to explore the better binding interactions and drugs likeness respectively.

Synthesis, In Vitro Biological Evaluation and Molecular Modeling of Benzimidazole-Based Pyrrole/Piperidine Hybrids Derivatives as Potential Anti-Alzheimer Agents.

Benzimidazole-based pyrrole/piperidine analogs (1-26) were synthesized and then screened for their acetylcholinesterase and butyrylcholinesterase activities. All the analogs showed good to moderate cholinesterase activities. Synthesized compounds (1-13) were screened in cholinesterase enzyme inhibition assays and showed AChE activities in the range of IC50 = 19.44 ± 0.60 µM to 36.05 ± 0.4 µM against allanzanthane (IC50 = 16.11 ± 0.33 µM) and galantamine (IC50 = 19.34 ± 0.62 µM) and varied BuChE inhibitory activities, with IC50 values in the range of 21.57 ± 0.61 µM to 39.55 ± 0.03 µM as compared with standard allanzanthane (IC50 = 18.14 ± 0.05 µM) and galantamine (IC50 = 21.45 ± 0.21 µM). Similarly, synthesized compounds (14-26) were also subjected to tests to determine their in vitro AChE inhibitory activities, and the results obtained corroborated that all the compounds showed varied activities in the range of IC50 = 22.07 ± 0.13 to 42.01 ± 0.02 µM as compared to allanzanthane (IC50 = 20.01 ± 0.12 µM) and galantamine (IC50 = 18.05 ± 0.31 µM) and varied BuChE inhibitory activities, with IC50 values in the range of 26.32 ± 0.13 to 47.03 ± 0.15 µM as compared to standard allanzanthane (IC50 = 18.14 ± 0.05 µM) and galantamine (IC50 = 21.45 ± 0.21 µM). Binding interactions of the most potent analogs were confirmed through molecular docking studies. The active analogs 2, 4, 10 and 13 established numerous interactions with the active sites of targeted enzymes, with docking scores of -10.50, -9.3, -7.73 and -7.8 for AChE and -8.97, -8.2, -8.20 and -7.6 for BuChE, respectively.

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.

Pharmacological evaluations of amide carboxylates as potential anti-Alzheimer agents: anti-radicals, enzyme inhibition, simulation and behavioral studies in animal models

Alzheimer’s disease (AD) is a neurological disorder that progresses gradually but irreversibly leading to dementia and is difficult to prevent and treat. There is a considerable time window in which the progression of the disease can be intervened. Scientific advances were required to help the researchers to identify the effective methods for the prevention and treatment of disease. This research was designed to investigate potential mediators for the remedy of AD, five new carboxylate amide zinc complexes (AAZ9–AAZ13) were synthesized and characterized by spectroscopic and physicochemical techniques. The biological evaluation was carried out based on the cholinesterase inhibitory mechanism. The preparation methodology provided the effective synthesis of targeted moieties. The in vitro pharmacological activities were evaluated involving AChE/BChE inhibition and antioxidant potential. All synthesized compounds displayed activity against both enzymes in higher or comparable to the standard drug Galantamine, a reversible inhibitor but the results displayed by compound AAZ10 indicated IC50 of 0.0013 µM (AChE) and 0.061 µM (BChE) as high values for dual AChE/BChE inhibition with potent anti-oxidant results. Structure activity relationship (SAR) indicated that the potent activity of compound AAZ10 appeared due to the presence of nitro clusters at the ortho position of an aromatic ring. The potent synthesized compound AAZ10 was also explored for the in-vivo Anti-Alzheimer activity and anti-oxidant activity. Binding approaches of all synthesized compounds were revealed through molecular docking studies concerning binding pockets of enzymes that analyzed the best posture interaction with amino acid (AA) residues providing an appreciable understanding of enzyme inhibitory mechanisms. Results indicate that synthesized zinc (II) amide carboxylates can behave as an effective remedy in the treatment of Alzheimer’s disease. Communicated by Ramaswamy H. Sarma

Investigation of Novel Benzoxazole-Oxadiazole Derivatives as Effective Anti-Alzheimer's Agents: In Vitro and In Silico Approaches.

Alzheimer's disease (AD) is a progressive neurological illness that is distinguished clinically by cognitive and memory decline and adversely affects the people of old age. The treatments for this disease gained much attention and have prompted increased interest among researchers in this field. As a springboard to explore new anti-Alzheimer's chemical prototypes, the present study was carried out for the synthesis of benzoxazole-oxadiazole analogues as effective Alzheimer's inhibitors. In this research work, we have focused our efforts to synthesize a series of benzoxazole-oxadiazole (1-19) and evaluating their anti-Alzheimer properties. In addition, the precise structures of synthesized derivatives were confirmed with the help of various spectroscopic techniques including 1H-NMR, 13C-NMR and HREI-MS. To find the anti-Alzheimer potentials of the synthesized compounds (1-19), in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), inhibitory activities were performed using Donepezil as the reference standard. From structure-activity (SAR) analysis, it was confirmed that any variation found in inhibitory activities of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes were due to different substitution patterns of substituent(s) at the variable position of both acetophenone aryl and oxadiazole aryl rings. The results of the anti-Alzheimer assay were very encouraging and showed moderate to good inhibitory potentials with IC50 values ranging from 5.80 ± 2.18 to 40.80 ± 5.90 µM (against AChE) and 7.20 ± 2.30 to 42.60 ± 6.10 µM (against BuChE) as compared to standard Donepezil drug (IC50 = 33.65 ± 3.50 µM (for AChE) and 35.80 ± 4.60 µM (for BuChE), respectively. Specifically, analogues 2, 15 and 16 were identified to be significantly active, even found to be more potent than standard inhibitors with IC50 values of 6.40 ± 1.10, 5.80 ± 2.18 and 6.90 ± 1.20 (against AChE) and 7.50 ± 1.20, 7.20 ± 2.30 and 7.60 ± 2.10 (against BuChE). The results obtained were compared to standard drugs. These findings reveal that benzoxazole-oxadiazole analogues act as AChE and BuChE inhibitors to develop novel therapeutics for treating Alzheimer's disease and can act as lead molecules in drug discovery as potential anti-Alzheimer agents.

Evaluation of derivatives of 2,3-dihydroquinazolin-4(1H)-one as inhibitors of cholinesterases and their antioxidant activity: In vitro, in silico, and kinetics studies

In search of potent inhibitors of cholinesterase enzymes and antioxidant agents, synthetic derivatives of dihydroquinazolin-4(1H)-one (1?38) were evaluated as potential anti-Alzheimer agents through in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitions and radical (DPPH and ABTS) scavenging activities. The structure?activity relationship (SAR) was mainly based on the different substituents at the aryl part which showed a significant effect on the inhibitory potential of enzymes and radical scavenging activities. The kinetic studies of most active compounds showed a noncompetitive mode of inhibition for AChE and a competitive mode of inhibition for the BChE enzyme. Additionally, molecular modelling studies were carried out to investigate the possible binding interactions of quinazolinone derivatives with the active site of both enzymes.

Synthesis, Characterisation and Docking Studies of Thioxoquinoline Derivatives as Potential Anti-Alzheimer Agents.

Alzheimer's Disease (AD) is related to the total loss of presynaptic neurotransmitters of the cholinergic system in regions of the brain related to memory. Approximately 15% of the population beyond the age of 65 years are suffering from dementia due to AD and the rate is rising exponentially with age. The objective of this research was the synthesis of a series of 1-(4-substituted-2- thioxoquinolin-1(2H)-yl)-2-substituted ethanoneV (a-c(1-4)) by undergoing acetylation at the nitrogen of 4-hydroxyquinolin-2-(1H)-one and replacing its oxygen atom with sulphur moiety via the process of thionation. To carry out-docking studies of the title compounds were carried out using Molegro Virtual Docker (MVD-2013, 6.0) software and in-vitro screening of anti-alzheimer's activity by Ellman assay method. The synthesis of the title compounds was carried out via the sequential reaction from the initial dianilide to ring closure to the substituted quinoline-2-ones using polyphosphoric acid as a cyclising agent. These substituted quinoline-2-ones on thionation by phosphorous pentasulphide in aluminium trioxide gave quinoline-2-thiones and on further condensation with chloroacetyl chloride, they resulted in compounds with a leaving group. Nucleophilic substitution reaction of chloroacetylquinoline- 2-thiones with secondary amines resulted in the title compounds 1-(4-substituted-2- thioxoquinolin-1(2H)-yl)-2-substituted ethanone V(a-c(1-4)). The pharmacophore mapping of synthesized compounds was performed by using Molegro Virtual Docker (MVD-2013,6.0). The title compounds were tested for their in vitro anti-Alzheimer's activity using the Ellman assay method. All the synthesized compounds were characterized by IR, 1H NMR, 13C NMR, and Mass spectral data. Docking studies of all the synthesized compounds were carried out using a structural mechanism for the inhibition of CDK5-p25 by roscovitine, aloisine, and indirubin (PDB ID: 1UNG), showed favourable results, with compound (Vb3) showing a MolDock score of -85.9788 that was comparable to that of the active ligand (ALH_1288 [B]) with MolDock score of - 87.7609. The synthesized derivatives possessed the potential to bind with some of the amino acid residues of the active site. Compound 2-(6-chloro-4-hydroxy-2-thioxoquinolin-1(2H)-yl-1-piperazin- 1-ethanone (Vb3) was found to be the most active among the synthesized derivatives, with IC50 values of 32 ± 0.1681. All the synthesized compounds showed potent to moderate activity in comparison to the reference standard donepezil.

Development of new donepezil analogs: synthesis, biological screening and in silico study rational

Fifteen new benzothiophene-based compounds were designed, synthesized, and evaluated as potential anti-Alzheimer agents. Most of the synthesized compounds exhibited remarkable AChE inhibitory activity and effectively inhibited self-mediated β-amyloid protein in vitro. Compound 3g (IC50 = 72.488 ± 3.69 μM) showed a significant β-amyloid inhibitory effect exceeding that of donepezil (IC50 = 87.414 ± 4.46 μM). Furthermore, compound 3j (IC50 = 0.498 ± 0.02 μM) showed the best inhibitory activity comparable to that of donepezil (IC50 = 0.404 ± 0.03 μM). The in vivo evaluation of the promising compounds (3g and 3j) confirmed a significant memory improvement in scopolamine-induced memory impairment model in mice. The molecular docking simulation of compounds 3g and 3j in Torpedo californica-AChE (TcAChE) active site showed a good agreement with the obtained screening results. The in silico ADMET and other physicochemical parameters were also reported.

2D QSAR, design, docking study and ADMET of some N-aryl derivatives concerning inhibitory activity against Alzheimer disease

BackgroundAlzheimer disease (AD) is an ailment that disturbs mainly people of old age. The fundamental remedial way to deal with AD depends on the utilization of AChEI. The design of new intense and particular AChEI is critical in drug discovery. In silico technique will be used to solve the above problem. A new method was established to discover novel agents with better biological activity against Alzheimer disease.ResultsA validated model was established in this research to predict the biological activities of some anti-Alzheimer compounds and to design new hypothetical drugs influenced with molecular properties in the derived model; ATS4i, MATS2e, SpMax7_BhS, Energy(HOMO) and Molecular Weight and showed good correlation R2 = 0.936, R2adj = 0.907, Q2cv = 0.88, LOF = 0.0154 and R2ext = 0.881. All the descriptors in the model were in good agreement with the 15 test set predicted values. Five compounds were designed using D35rm as a template with improved activity. The compounds have higher and better binding scores (− 10.1, − 9.4, − 9.3, − 9.1 and − 8.1 all in kcal/mol) than the approved drugs (Donepezil = − 7.4 kcal/mol).ConclusionAs the outcome, every one of the selected and the designed compounds is created and improved as potential anti-Alzheimer agents. Despite this, the further test examines and in vivo investigations are recommended to assess the method of the activities and other pharmacological impacts on these compounds.

Marine Organisms as Alkaloid Biosynthesizers of Potential Anti-Alzheimer Agents.

The incidence of neurodegenerative diseases, such as Alzheimer’s disease (AD), increases continuously demanding the urgent development of anti-Alzheimer’s agents. Marine organisms (MO) have to create their own defenses due to the adverse environment where they live and so synthesize several classes of compounds, such as akaloids, to defend themselves. Therefore, the identification of marine natural products with neuroprotective effects is a necessity. Being that AD is not only a genetic but also an environmental complex disease, a treatment for AD remains to discover. As the major clinical indications (CI) of AD are extracellular plaques formed by β-amyloid (Aβ) protein, intracellular neurofibrillary tangles (NFTs) formed by hyper phosphorylated τ-protein, uncommon inflammatory response and neuron apoptosis and death caused by oxidative stress, alkaloids that may decrease CI, might be used against AD. Most of the alkalolids with those properties are derivatives of the amino acid tryptophan mainly with a planar indole scaffold. Certainly, alkaloids targeting more than one CI, multitarget-directed ligands (MTDL), have the potential to become a lead in AD treatment. Alkaloids to have a maximum of activity against CI, should be planar and contain halogens and amine quaternization.

Conformational analysis, molecular structure, spectroscopic, NBO, reactivity descriptors, wavefunction and molecular docking investigations of 5,6-dimethoxy-1-indanone: A potential anti Alzheimer's agent

The objective of the present study is focused to elucidate the structure of potential anti-Alzheimer's compound 5,6-Dimethoxy-1-indanone (5,6-DMI) and study its binding interaction towards the active site by molecular docking studies. The structural and various spectroscopic tools are used to understand the various interaction behaviors of the title compound. The theoretical calculation of 5,6-DMI molecule is computed by Gaussian 09W software with Density functional B3LYP and CAM-B3LYP method utilizing 6-311G(d,p) as basis set. The Natural Bond Orbital (NBO) analysis has been performed to find all possible transition was correlate with electronic transition. The Non covalent interaction of 5,6-DMI molecule was examined by adopt Reduced Density Gradient (RDG) analysis and colour filled ELF diagram. Molecular docking results suggest that 5,6-DMI may exhibit inhibitory activity against apoE protein and may act as potential against Alzheimer's disease.

Synthesis, and in vitro biological evaluations of novel naphthoquinone conjugated to aryl triazole acetamide derivatives as potential anti-Alzheimer agents

Alzheimer's disease is a neurodegenerative disorder that deteriorates mental ability. Two main cholinesterases named, acetylcholinesterase and butyrylcholinesterase are potential targets against Alzheimer's disease. Cholinesterase inhibitors have beneficial effects to increase brain acetylcholine amounts resulting in neurocognitive function. In the present article, fifteen small molecules of 1, 4-naphthoquinone conjugated to aryl triazole acetamide derivatives were rationally designed, synthesized, and evaluated for their anti-ChE activities followed by molecular docking assessments. Among synthesized derivatives, 7b bearing ortho-chlorine moiety was the strongest inhibitor of acetylcholinesterase and butyrylcholinesterase with Ki values of 10.16 and 8.04 nM respectively compared to the Tacrine as a positive control with Ki = 70.61 and 64.18 nM. Docking studies confirmed the complete fitting of the 7b into the active sites of both enzymes.

Potential Anti-Alzheimer Agents from Guanidinyl Tryptophan Derivatives with Activities of Membrane Adhesion and Conformational Transition Inhibitions.

Guanidinyl tryptophan derivatives TGN1, TGN2, TGN3, and TGN4 were synthesized, and these compounds were shown to possess in vitro inhibitory activity for amyloid aggregation in a previous study. Nevertheless, the influence of the TGN series of compounds on the binding and permeation behaviors of an Aβ monomer to the cell membranes was not elucidated. In this study, we investigated the effect of compounds in the TGN series on the behavior of an Aβ monomer regarding its toxicity toward the bilayer lipid membrane using molecular dynamics (MD) simulation. MD simulations suggest that TGN4 is a potential agent that can interfere with the movement of the Aβ monomer into the membrane. The MM-GBSA result demonstrated that TGN4 exhibits the highest affinity to the Aβ1–42 monomer but has the lowest affinity to the bilayer. Moreover, TGN4 also contributes to a decrease in the binding affinity between the Aβ1–42 monomer and the POPC membrane. Regarding the results of the binding mode and conformational analyses, a high number of amino-acid residues were shown to provide the binding interactions between TGN4 and the Aβ1–42 monomer. TGN4 also reduces the conformational transition of the Aβ1–42 monomer by means of interacting with the monomer. The present study presents molecular-level insights into how the TGN series of compounds affect the membrane adsorption and the conformational transition of the Aβ1–42 monomer, which could be valuable for the further development of new anti-Alzheimer agents.

Prospective Application of Two New Pyridine-Based Zinc (II) Amide Carboxylate in Management of Alzheimer's Disease: Synthesis, Characterization, Computational and in vitro Approaches.

BackgroundAlzheimer’s disease (AD) is a neurodegenerative illness described predominantly by dementia. Even though Alzheimer’s disease has been known for over a century, its origin remains a mystery, and researchers are exploring many therapy options, including the cholinesterase technique. A decreased acetylcholine ACh neurotransmitter level is believed to be among the important factors in the progression of Alzheimer’s disease.MethodsIn continuation of synthesizing potential anti-Alzheimer agents and known appreciative pharmacological potential of amide-containing compounds, this study presents the synthesis of two novel amide-based transition metal zinc (II) complexes, AAZ7 and AAZ8, attached with a heterocyclic pyridine ring, which was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis, 1H_NMR, and 13C_NMR. FT-IR spectroscopic records showed the development of bidentate ligand as Δν value was decreased in both complexes when compared with the free ligand. Both of the synthesized complexes were analyzed for acetylcholinesterase and butyrylcholinesterase inhibitory potential along with the antioxidizing activity.ResultsImportantly, the complex of AAZ8 exhibited more potent activity giving IC50 values of 14 µg/mL and 18µg/mL as AChE and BChE cholinesterase inhibitors, respectively, when compared with standard positive control galantamine. Interestingly, AAZ8 also displayed promising antioxidant potential by showing IC50 values of 35 µg/mL for DPPH and 29 µg/mL for ABTS in comparison with positive control ascorbic acid.ConclusionHerein, we report two new amide carboxylate zinc (II) complexes which were potentially analyzed for various biological applications like acetylcholinesterase (AChE), butyrylcholinesterase (BChE) inhibitory potentials, and antioxidant assays. Computational docking studies also simulated results to understand the interactions. Additionally, thermodynamic parameters utilizing molecular dynamic simulation were performed to determine the ligand protein stability and flexibility that supported the results. Studies have shown that these compounds have the potential to be good anti-Alzheimer candidates for future studies due to inhibition of cholinesterase enzymes and display of free radical scavenging potential against DPPH as well as ABTS free radicals.

Vilazodone-Tacrine Hybrids as Potential Anti-Alzheimer Agents: QSAR, Molecular Docking, and Molecular Dynamic (MD) Simulation Studies

Alzheimer's disease (AD) is a type of functional impairment of the brain, which gently degrades the patients' mental potency. The goal pursued in this study is to introduce novel drug candidates as acetylcholinesterase (hAChEIs) and butyl cholinesterase (hBuChE) inhibitors in the treatment of AD. In this study, more than 100 Vilazodone-Tacrin hybrids have been designed to inhibit hAchE and hBuChE. A series of chemical methods such as multiple linear regression (MLR) and GA-PLS were used to create relationships between structural features in these compounds and their hAchE/ hBuChE inhibitory activity. Molecular docking studies against hAChE (PDB ID: 1ACJ) and hBuChE (PDB ID: 4BDS) indicates the important amino acids inside the active site cavity that are responsible of essential interactions were Gly441, Ser122, Trp84, Asp72, Tyr130, and Gly117 for hAChE and Glu197, Thr120, Gly121, Asn83, Tyr332, Trp430, Trp82 and Asp70 for hBuChE. The best regression equation was obtained from GA-PLS, which predicts 92% of variances. Molecular dynamic (MD) simulations were also studied. The reliability, accuracy, and predictability of the proposed QSAR models were evaluated. Finally, an in silico screening study was conducted, and some compounds were introduced as logical candidates as novel anti-Alzheimer agents.

The translocator protein ligands as mitochondrial functional modulators for the potential anti-Alzheimer agents

Small molecule modulators of mitochondrial function have been attracted much attention in recent years due to their potential therapeutic applications for neurodegenerative diseases. The mitochondrial translocator protein (TSPO) is a promising target for such compounds, given its involvement in the formation of the mitochondrial permeability transition pore in response to mitochondrial stress. In this study, we performed a ligand-based pharmacophore design and virtual screening, and identified a potent hit compound, 7 (VH34) as a TSPO ligand. After validating its biological activity against amyloid-β (Aβ) induced mitochondrial dysfunction and in acute and transgenic Alzheimer’s disease (AD) model mice, we developed a library of analogs, and we found two most active compounds, 31 and 44, which restored the mitochondrial membrane potential, ATP production, and cell viability under Aβ-induced mitochondrial toxicity. These compounds recovered learning and memory function in acute AD model mice with improved pharmacokinetic properties.

Natural Products as Potential Anti-Alzheimer Agents.

Medicinal plants have curative properties due to the presence of various complex chemical substances of different composition, which are found as secondary metabolites in one or more parts of the plant. The diverse secondary metabolites play an important role in the prevention and cure of various diseases including neurodegenerative diseases like Alzheimer's disease. Naturally occurring compounds such as flavonoids, polyphenols, alkaloids, and glycosides found in various parts of the plant and/or marine sources may potentially protect neurodegeneration as well as improve memory and cognitive function. Many natural compounds show anti-Alzheimer activity through specific pharmacological mechanisms like targeting β-amyloid, Beta-secretase 1 and Acetylcholinesterase. In this review, we have compiled more than 130 natural products with a broad diversity in the class of compounds, which were isolated from different sources showing anti- Alzheimer properties.

Novel Benzylated (Pyrrolidin-2-one)/(Imidazolidin-2-one) Derivatives as Potential Anti-Alzheimer's Agents: Synthesis and Pharmacological Investigations.

A series of N-benzylated (pyrrolidin-2-one)/(imidazolidin-2-one) derivatives were synthesized and evaluated for anti-Alzheimer's activity. The analogs were designed and synthesized on the basis of lead compound donepezil, which is currently prescribed as a major drug for the management of mild to severe Alzheimer's disease. Considering the structure activity relationship (SAR) of the lead compound, we first replaced the 5,6-dimethoxy-1-indanone moiety with N-benzylated (pyrrolidin-2-one)/(imidazolidin-2-one) (head) without depriving the key functionality interactions like carbonyl and dimethoxyphenyl and second substituted the spacer linkage (tail) in donepezil. The newly synthesized compounds were characterized by structural conformity and purity using various techniques. The compounds were then subjected to in vivo (behavioral studies) and in vitro (biochemical assays) evaluation using appropriate animal models against the standard drug. Compounds 3-(4-(4-fluorobenzoyl)-piperidin-1-yl)-1-(4-methoxybenzyl)-pyrrolidin-2-one (10b) and 1-(3,4-dimethoxybenzyl)-3-((1-(2-(trifluoromethyl)-benzyl)-piperidin-4-yl)-methyl)-imidazolidin-2-one (18c) displayed an excellent anti-Alzheimer's profile, while the rest of the compounds showed satisfactory results in comparison to donepezil.

Design, synthesis and biological activity evaluation of novel carbazole-benzylpiperidine hybrids as potential anti Alzheimer agents

Alzheimer’s disease (AD) as the most common form of dementia in aged people, is an intricate neurodegenerative disease. Therefore, a novel strategy so-called multi-target-directed ligand has received much attention for the effective treatment of AD. In this study a series of novel carbazole-benzylpiperidine hybrids 9a-m was designed, synthesized and evaluated as acetylcholinesterase and butyrylcholinesterase inhibitors. Moreover, some of these compounds were evaluated for anti β-secretase (BACE1) activity and metal chelation properties. Among the synthesized compounds, compounds 9b (IC50 = 16.5 μM for AChE and IC50 = 0.59 μM for BuChE) and 9c (IC50 = 26.5 μM for AChE and IC50 = 0.18 μM for BuChE) showed the highest inhibitory activity against acetylcholinesterase and butyrylcholinesterase. Furthermore, these compounds (9b and 9c) displayed interaction with Zn2+ ion and compound 9c showed moderate inhibitory activity against BACE1 (24.5% at 50 μM). Kinetic and docking studies exhibited that these compounds likely act as a non-competitive inhibitor able to interact with the catalytic active site (CAS) and peripheral anionic site (PAS) of acetylcholinesterase simultaneously.

Spiro Heterocyclic Compounds as Potential Anti-Alzheimer Agents (Part 2): Their Metal Chelation Capacity, POM Analyses and DFT Studies.

One of the best methods to treat Alzheimer disease (AD) is through the effective use of cholinesterase inhibitors as vital drugs due to the identification of acetylcholine deficit in the AD patients. The present study aims the investigation of spiro heterocyclic compounds as potential AD agents supported by their metal chelation capacity, POM analyses and DFT studies, respectively. The cholinesterase inhibition and metal chelation ability were performed on ELISA microtiter assay. Whereas, the B3LYP method with 6-31+G(d,p) basis set was implemented to study HOMOLUMO energy calculations. The pharmacokinetic properties of the synthesized molecules were studied through Petra, Osiris and Molinspiration (POM). The six spiro (1-6) skeletons were tested for their inhibitory potential and metal-chelation capacity. Our findings revealed that the tested spiro skeletons exerted none or lower than 50% inhibition against both cholinesterases, while compound 4 proved to be the most active molecule with 57.21±0.89% of inhibition toward BChE. The spiro molecule 3 exhibited the highest metal-chelation capacity (9.12±5.26%). Molecular docking model for the most active molecule exhibited promising bindings with AChE and BChE's active site pertained to hydrophobic hydrogen bonds and positive ionizable interactions. The POM analyses gave the information about the flexibility at the site of coordination of spiro compounds (1-6). The screening of spirocompounds (1-6) against cholinesterases revealed that some of them show considerable potential to inhibit AChE and BChE. Herein, we propose that the spiro molecules after further derivatization could serve interesting AD inhibitor drugs.