Synthesis, molecular docking, acetylcholinesterase and butyrylcholinesterase inhibitory potential of thiazole analogs as new inhibitors for Alzheimer disease

Structure-Guided Design, Synthesis, and Biological Evaluation of Peripheral Anionic Site Selective and Brain Permeable Novel Oxadiazole-Piperazine Conjugates against Alzheimer's Disease with Antioxidant Potential

Alzheimer's disease (AD) is a multifactorial and emerging neurological disorder, which has invoked researchers to develop multitargeted ligands. Herein, hybrid conjugates of 5-phenyl-1,3,4-oxadiazole and piperazines were rationally designed, synthesized, and pharmacologically evaluated against hAChE, hBChE, and hBACE-1 enzymes for the management of AD. Among the series, compound 5AD comprising pyridyl substitution at terminal nitrogen of piperazine contemplated as a paramount lead compound (hAChE, IC50 = 0.103 ± 0.0172 μM, hBChE, IC50 ≥ 10 μM, and hBACE-1, IC50 = 1.342 ± 0.078 μM). Compound 5AD showed mixed-type enzyme inhibition in enzyme kinetic studies against the hAChE enzyme. In addition, compound 5AD revealed a significant displacement of propidium iodide from the peripheral anionic site (PAS) of hAChE and excellent blood-brain barrier (BBB) permeability in a parallel artificial membrane permeation assay (PAMPA). Besides, 5AD also exhibited anti-Aβ aggregation activity in self- and AChE-induced thioflavin T assay. Further, compound 5AD has shown significant improvement in learning and memory (p < 0.001) against the in vivo scopolamine-induced cognitive dysfunction mice model. The ex vivo study implied that after treatment with compound 5AD, there was a decrease in AChE and malonaldehyde (MDA) levels with an increase in catalase (CAT, oxidative biomarkers) in the hippocampal brain homogenate. Hence, compound 5AD could be regarded as a lead compound and further be explored in the treatment of AD.

Discovering phenoxy acetohydrazide derivatives as urease inhibitors and molecular docking studies

Helicobacter pylori causes severe stomach disorders and the use of enzyme inhibitors for treatment is one of the possible therapies. The great biological potential of imine analogs as urease inhibitors has been the focus of researchers in past years. In this regard, we have synthesized twenty-one derivatives of dichlorophenyl hydrazide. These compounds were characterized by different spectroscopic techniques i.e. NMR and HREI-MS. Compounds 2 and 10 were found to be the most active in the series. Structure-activity relationship has been established for all compounds based on different substituents attached to the phenyl ring that play a vital role in enzyme inhibition. From the structure-activity relationship, it has been observed that these analogs showed excellent potential for urease and can be an alternate therapy in the future. The molecular docking study was performed to further explore the binding interactions of synthesized analogs with enzyme active sites.Communicated by Ramaswamy H. Sarma.

Design, synthesis and evaluation of aminothiazole derivatives as potential anti-Alzheimer's candidates

Aim: The objective of the present study was to design, synthesize and evaluate diverse Schiff bases and thiazolidin-4-one derivatives of aminothiazole as key pharmacophores possessing acetylcholinesterase inhibitory activity. Materials & methods: Two series of compounds (13 each) were synthesized and evaluated for their acetylcholinesterase inhibition and antioxidant activity. Molecular docking of all compounds was performed to provide an insight into their binding interactions. Results: Compounds 2j (IC50 = 0.03 μM) and 3e (IC50 = 1.58 μM) were found to be the best acetylcholinesterase inhibitors among compounds of their respective series. Molecular docking analysis supported the results of in vitro activity by displaying good docking scores with the binding pocket of human acetylcholinesterase (Protein Data Bank ID: 4EY7). Conclusion: Compound 2j emerged as a potential lead compound with excellent acetylcholinesterase inhibition, antioxidant and chelation activity.

Imidazopyridine-Based Thiazole Derivatives as Potential Antidiabetic Agents: Synthesis, In Vitro Bioactivity, and In Silico Molecular Modeling Approach

A new series of thiazole derivatives (4a-p) incorporating imidazopyridine moiety was synthesized and assessed for their in vitro potential α-glucosidase potency using acarbose as a reference drug. The obtained results suggested that compounds 4a (docking score = -13.45), 4g (docking score = -12.87), 4o (docking score = -12.15), and 4p (docking score = -11.25) remarkably showed superior activity against the targeted α-glucosidase enzyme, with IC50 values of 5.57 ± 3.45, 8.85 ± 2.18, 7.16 ± 1.40, and 10.48 ± 2.20, respectively. Upon further investigation of the binding mode of the interactions by the most active scaffolds with the α-glucosidase active sites, the docking analysis was accomplished in order to explore the active cavity of the α-glucosidase enzyme. The interpretation of the results showed clearly that scaffolds 4a and 4o emerged as the most potent α-glucosidase inhibitors, with promising excellent binding interactions with the active site of the α-glucosidase enzyme. Furthermore, utilizing a variety of spectroscopic methods, such as 1H-NMR, 13C-NMR, and HREI-MS, the precise structures of the synthesized scaffolds were determined.

Synthesis and In Vitro α-Amylase and α-Glucosidase Dual Inhibitory Activities of 1,2,4-Triazole-Bearing bis-Hydrazone Derivatives and Their Molecular Docking Study

There is an increasing prevalence of diabetes mellitus throughout the world, and new compounds are necessary to combat this. The currently available antidiabetic therapies are long-term complicated and side effect-prone, and this has led to a demand for more affordable and more effective methods of tackling diabetes. Research is focused on finding alternative medicinal remedies with significant antidiabetic efficacy as well as low adverse effects. In this research work, we have focused our efforts to synthesize a series of 1,2,4-triazole-based bis-hydrazones and evaluated their antidiabetic properties. In addition, the precise structures of the synthesized derivatives were confirmed with the help of various spectroscopic techniques including ¹H-NMR, ¹³C-NMR, and HREI-MS. To find the antidiabetic potentials of the synthesized compounds, in vitro α-glucosidase and α-amylase inhibitory activities were characterized using acarbose as the reference standard. From structure-activity (SAR) analysis, it was confirmed that any variation found in inhibitory activities of both α-amylase and α-glucosidase enzymes was due to the different substitution patterns of the substituent(s) at variable positions of both aryl rings A and B. The results of the antidiabetic assay were very encouraging and showed moderate to good inhibitory potentials with IC₅₀ values ranging from 0.70 ± 0.05 to 35.70 ± 0.80 μM (α-amylase) and 1.10 ± 0.05 to 30.40 ± 0.70 μM (α-glucosidase). The obtained results were compared to those of the standard acarbose drug (IC₅₀ = 10.30 ± 0.20 μM for α-amylase and IC₅₀ = 9.80 ± 0.20 μM for α-glucosidase). Specifically, compounds 17, 15, and 16 were found to be significantly active with IC₅₀ values of 0.70 ± 0.05, 1.80 ± 0.10, and 2.10 ± 0.10 μM against α-amylase and 1.10 ± 0.05, 1.50 ± 0.05, and 1.70 ± 0.10 μM against α-glucosidase, respectively. These findings reveal that triazole-containing bis-hydrazones act as α-amylase and α-glucosidase inhibitors, which help develop novel therapeutics for treating type-II diabetes mellitus and can act as lead molecules in drug discovery as potential antidiabetic agents.

Therapeutic potential of 1,3,4-oxadiazoles as potential lead compounds for the treatment of Alzheimer's disease

Monoamine oxidase and cholinesterase enzymes are important targets for the treatment of several neurological diseases especially depression, Parkinson disease and Alzheimer's. Here, we report the synthesis and testing of new 1,3,4-oxadiazole derivatives as novel inhibitors of monoamine oxidase enzymes (MAO-A and MAO-B) and cholinesterase enzymes (acetyl and butyryl cholinesterase (AChE, BChE). Compounds 4c, 4d, 4e, 4g, 4j, 4k, 4m, 4n displayed promising inhibitory effects on MAO-A (IC₅₀: 0.11-3.46 μM), MAO-B (IC₅₀: 0.80-3.08 μM) and AChE (IC₅₀: 0.83-2.67 μM). Interestingly, compounds 4d, 4e and 4g are multitargeting MAO-A/B and AChE inhibitors. Also, Compound 4m displayed promising MAO-A inhibition with IC₅₀ of 0.11 μM and high selectivity (∼25-fold) over MAO-B and AChE enzymes. These newly synthesized analogues represent promising hits for the development of promising lead compounds for neurological disease treatment.

Synthesis, in vitro biological screening and docking study of benzo[d]oxazole bis Schiff base derivatives as a potent anti-Alzheimer agent

We have synthesized benzo[d]oxazole derivatives (1-21) through a multistep reaction. Alteration in the structure of derivatives was brought in the last step via using various substituted aromatic aldehydes. In search of an anti-Alzheimer agent, all derivatives were evaluated against acetylcholinesterase and butyrylcholinesterase enzyme under positive control of standard drug donepezil (IC₅₀ = 0.016 ± 0.12 and 4.5 ± 0.11 µM) respectively. In case of acetylcholinesterase enzyme inhibition, derivatives 8, 9 and 18 (IC₅₀ = 0.50 ± 0.01, 0.90 ± 0.05 and 0.3 ± 0.05 µM) showed very promising inhibitory potentials. While in case of butyrylcholinesterase enzyme inhibition, most of the derivatives like 6, 8, 9, 13, 15, 18 and 19 (IC₅₀ = 2.70 ± 0.10, 2.60 ± 0.10, 2.20 ± 0.10, 4.25 ± 0.10, 3.30 ± 0.10, 0.96 ± 0.05 and 3.20 ± 0.10 µM) displayed better inhibitory potential than donepezil. Moreover, derivative 18 is the most potent one among the series in both inhibitions. The binding interaction of derivatives with the active gorge of the enzyme was confirmed via a docking study. Furthermore, the binding interaction between derivatives and the active site of enzymes was correlated through the SAR study. Structures of all derivatives were confirmed through spectroscopic techniques such as ¹H-NMR, ¹³C-NMR and HREI-MS, respectively.Communicated by Ramaswamy H. Sarma.

Biologically Potent Benzimidazole-Based-Substituted Benzaldehyde Derivatives as Potent Inhibitors for Alzheimer's Disease along with Molecular Docking Study

Twenty-one analogs were synthesized based on benzimidazole, incorporating a substituted benzaldehyde moiety (1-21). These were then screened for their acetylcholinesterase and butyrylcholinesterase inhibition profiles. All the derivatives except 13, 14, and 20 showed various inhibitory potentials, ranging from IC50 values of 0.050 ± 0.001 µM to 25.30 ± 0.40 µM against acetylcholinesterase, and 0.080 ± 0.001 µM to 25.80 ± 0.40 µM against butyrylcholinesterase, when compared with the standard drug donepezil (0.016 ± 0.12 µM and 0.30 ± 0.010 µM, against acetylcholinesterase and butyrylcholinesterase, respectively). Compound 3 in both cases was found to be the most potent compound due to the presence of chloro groups at the 3 and 4 positions of the phenyl ring. A structure-activity relationship study was performed for all the analogs except 13, 14, and 20, further, molecular dynamics simulations were performed for the top two compounds as well as the reference compound in a complex with acetylcholinesterase and butyrylcholinesterase. The molecular dynamics simulation analysis revealed that compound 3 formed the most stable complex with both acetylcholinesterase and butyrylcholinesterase, followed by compound 10. As compared to the standard inhibitor donepezil both compounds revealed greater stabilities and higher binding affinities for both acetylcholinesterase and butyrylcholinesterase.

Synthesis, DFT Studies, Molecular Docking and Biological Activity Evaluation of Thiazole-Sulfonamide Derivatives as Potent Alzheimer's Inhibitors

Alzheimer's disease is a major public brain condition that has resulted in many deaths, as revealed by the World Health Organization (WHO). Conventional Alzheimer's treatments such as chemotherapy, surgery, and radiotherapy are not very effective and are usually associated with several adverse effects. Therefore, it is necessary to find a new therapeutic approach that completely treats Alzheimer's disease without many side effects. In this research project, we report the synthesis and biological activities of some new thiazole-bearing sulfonamide analogs (1-21) as potent anti-Alzheimer's agents. Suitable characterization techniques were employed, and the density functional theory (DFT) computational approach, as well as in-silico molecular modeling, has been employed to assess the electronic properties and anti-Alzheimer's potency of the analogs. All analogs exhibited a varied degree of inhibitory potential, but analog 1 was found to have excellent potency (IC₅₀ = 0.10 ± 0.05 µM for AChE) and (IC₅₀ = 0.20 ± 0.050 µM for BuChE) as compared to the reference drug donepezil (IC₅₀ = 2.16 ± 0.12 µM and 4.5 ± 0.11 µM). The structure-activity relationship was established, and it mainly depends upon the nature, position, number, and electron-donating/-withdrawing effects of the substituent/s on the phenyl rings.

Development of new Alzheimer's disease drug candidates using donepezil as a key model

Alzheimer's disease (AD) is one of the most prevalent geriatric diseases and a significant cause of high mortality. This crippling disorder is becoming more prevalent at an unprecedented rate, which has led to an increase in the financial cost of caring. It is a pathologically complicated, multifactorial disease characterized by β-amyloid precipitation, β-amyloid oligomer production, decrease in cholinergic function, and dysregulation of other neurotransmitter systems. Due to the pathogenic complexity of AD, multitarget drugs that can simultaneously alternate multiple biological targets may enhance the therapeutic efficacy. Donepezil (DNP) is the most potent approved drug for the treatment of AD. It has a remarkable effect on a number of AD-related processes, including cholinesterase activity, anti-Aβ aggregation, oxidative stress, and more. DNP resembles an excellent scaffold to be hybridized with other pharmacophoric moieties having biological activity against AD pathological factors. There have been significant attempts made to modify the structure of DNP to create new bioactive chemical entities with novel structural patterns. In this review, we highlight recent advances in the development of multiple-target DNP-hybridized models for the treatment of AD that can be used in the future in the rational design of new potential AD therapeutics. The design and development of new drug candidates for the treatment of AD using DNP as a molecular scaffold have also been reviewed and summarized.

Synthesis of New Triazole-Based Thiosemicarbazone Derivatives as Anti-Alzheimer's Disease Candidates: Evidence-Based In Vitro Study

Triazole-based thiosemicarbazone derivatives (6a-u) were synthesized then characterized by spectroscopic techniques, such as 1HNMR and 13CNMR and HRMS (ESI). Newly synthesized derivatives were screened in vitro for inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. All derivatives (except 6c and 6d, which were found to be completely inactive) demonstrated moderate to good inhibitory effects ranging from 0.10 ± 0.050 to 12.20 ± 0.30 µM (for AChE) and 0.20 ± 0.10 to 14.10 ± 0.40 µM (for BuChE). The analogue 6i (IC₅₀ = 0.10 ± 0.050 for AChE and IC₅₀ = 0.20 ± 0.050 µM for BuChE), which had di-substitutions (2-nitro, 3-hydroxy groups) at ring B and tri-substitutions (2-nitro, 4,5-dichloro groups) at ring C, and analogue 6b (IC₅₀ = 0.20 ± 0.10 µM for AChE and IC₅₀ = 0.30 ± 0.10 µM for BuChE), which had di-Cl at 4,5, -NO₂ groups at 2-position of phenyl ring B and hydroxy group at ortho-position of phenyl ring C, emerged as the most potent inhibitors of both targeted enzymes (AChE and BuChE) among the current series. A structure-activity relationship (SAR) was developed based on nature, position, number, electron donating/withdrawing effects of substitution/s on phenyl rings. Molecular docking studies were used to describe binding interactions of the most active inhibitors with active sites of AChE and BuChE.

Multipotent Cholinesterase Inhibitors for the Treatment of Alzheimer's Disease: Synthesis, Biological Analysis and Molecular Docking Study of Benzimidazole-Based Thiazole Derivatives

Twenty-four analogues of benzimidazole-based thiazoles (1-24) were synthesized and assessed for their in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory potential. All analogues were found to exhibit good inhibitory potential against cholinesterase enzymes, having IC50 values in the ranges of 0.10 ± 0.05 to 11.10 ± 0.30 µM (for AChE) and 0.20 ± 0.050 µM to 14.20 ± 0.10 µM (for BuChE) as compared to the standard drug Donepezil (IC50 = 2.16 ± 0.12 and 4.5 ± 0.11 µM, respectively). Among the series, analogues 16 and 21 were found to be the most potent inhibitors of AChE and BuChE enzymes. The number (s), types, electron-donating or -withdrawing effects and position of the substituent(s) on the both phenyl rings B & C were the primary determinants of the structure-activity relationship (SAR). In order to understand how the most active derivatives interact with the amino acids in the active site of the enzyme, molecular docking studies were conducted. The results obtained supported the experimental data. Additionally, the structures of all newly synthesized compounds were elucidated by using several spectroscopic methods like 13C-NMR, 1H-NMR and HR EIMS.

Synthesis, anticholinesterase activity, molecular docking, and molecular dynamic simulation studies of 1,3,4-oxadiazole derivatives

Two new series of 1,3,4-oxadiazoles bearing pyridine and thiazole heterocycles (4a-h and 5a-h) were synthesized (2,5-disubstituted-1,3,4-oxadiazoles). The structures of these newly synthesized compounds were confirmed by ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, high-resolution mass spectrometric and Fourier transform infrared spectroscopic methods. All these compounds were evaluated for their enzyme inhibitory activities against two cholinesterase enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). From the studies, we identified compounds 4a, 4h, 5a, 5d, and 5e as selective AChE inhibitors, with IC₅₀ values ranging from 0.023 to 0.037 μM. Furthermore, docking studies of these compounds were performed at the active sites of their target enzymes. The molecular docking study showed that 5e possessed an ideal docking pose with interactions inside AChE.

2-amino thiazole derivatives as inhibitors of some metabolic enzymes: An In Vitro and In Silico study

The thiazole derivatives are desirable compounds in the evaluation of their biological activities such as antiprotozoal antibacterial, antifungal, antituberculosis. Considering the medical application potential of 2-amino thiazole compounds, we aimed to determine the effects of 2-amino thiazole derivatives on the activities of carbonic anhydrase I-II isoenzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Among the chemicals we used in our study, 2-Amino-4-(4-chlorophenyl)thiazole compound exhibited the best inhibition against hCA I with K_i of 0.008±0.001 μM. The 2-Amino-4-(4-bromophenyl)thiazole compound exhibited the best inhibition against hCA II, AChE and BChE with K_i of 0.124±0.017 μM, 0.129±0.030 μM and 0.083±0.041 μM, respectively. Molecular docking analysis showed that compound 2-Amino-4-(5,6,7,8-tetrahydro-2-naphthyl)thiazole had the highest inhibitory potency against hCA I, hCA II, AChE, BChE with the estimated binding energy of -6.75 , -7.61, -7.86, -7.96 kcal/mol, respectively. This article is protected by copyright. All rights reserved.

Thiazole: A Versatile Standalone Moiety Contributing to the Development of Various Drugs and Biologically Active Agents

For many decades, the thiazole moiety has been an important heterocycle in the world of chemistry. The thiazole ring consists of sulfur and nitrogen in such a fashion that the pi (π) electrons are free to move from one bond to other bonds rendering aromatic ring properties. On account of its aromaticity, the ring has many reactive positions where donor–acceptor, nucleophilic, oxidation reactions, etc., may take place. Molecules containing a thiazole ring, when entering physiological systems, behave unpredictably and reset the system differently. These molecules may activate/stop the biochemical pathways and enzymes or stimulate/block the receptors in the biological systems. Therefore, medicinal chemists have been focusing their efforts on thiazole-bearing compounds in order to develop novel therapeutic agents for a variety of pathological conditions. This review attempts to inform the readers on three major classes of thiazole-bearing molecules: Thiazoles as treatment drugs, thiazoles in clinical trials, and thiazoles in preclinical and developmental stages. A compilation of preclinical and developmental thiazole-bearing molecules is presented, focusing on their brief synthetic description and preclinical studies relating to structure-based activity analysis. The authors expect that the current review may succeed in drawing the attention of medicinal chemists to finding new leads, which may later be translated into new drugs.

Pharmacophore mapping of the crucial mediators of acetylcholinesterase and butyrylcholinesterase dual inhibition in Alzheimer's disease

Optimization and re-optimization of bioactive molecules using in silico methods have found application in the design of more active ones. Herein, we applied a pharmacophore modeling approach to screen potent dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) aimed at Alzheimer's disease (AD) treatment. The investigation entails molecular dynamics simulation, docking, pharmacophore modeling, drug-like screening, and binding energy analysis. We prepared a pharmacophore model from approved inhibitors of AChE and BuChE to predict the crucial moieties required for optimum molecular interaction with these proteins. The obtained pharmacophore model, used for database screening via some critical criteria, showed 229 hit molecules. Further analyses showed 42 likely dual inhibitors of AChE/BuChE with drug-like and pharmacokinetics properties the same as the approved cholinesterase inhibitors. Finally, we identified 14 dual molecules with improved potentials over the existing inhibitors and simulated ZINC92385797 bound to human AChE and BuChE structure after noticing that these 14 molecules are similar. The selected compound maintained relative stability at the active sites of both proteins over 120 ns simulation. Our integrated protocols showed the pertinent recipes of anti-AD drug design through the in silico pipeline.

New biologically dynamic hybrid pharmacophore triazinoindole-based-thiadiazole as potent α-glucosidase inhibitors: In vitro and in silico study

Triazinoindole bearing thiadiazole derivatives (1-25) have been synthesized and characterized through different spectroscopic techniques such as ¹H, ¹³C-NMR and HREI-MS. The purpose of the study was to investigate the anti-diabetic activity of the synthesized triazinoindole bearing thiadiazole derivatives by inhibition of α-glucosidase. All synthesized analogues showed outstanding inhibition of α-glucosidase enzyme with IC₅₀ values ranging from 2.5 ± 0.10 to 38.10 ± 0.10 µM as compared to the standard drug acarbose (IC₅₀ = 38.45 ± 0.80 µM). Analogue 4 (IC₅₀ = 2.5 ± 0.10 µM) was identifies as the most potent analogue in the series with fifteen folds more active than standard acarbose. Structure activity relationship (SAR) studies suggested that α-glucosidase activities of triazinoindole bearing thiadiazole are primarily dependent upon on number and position of different substitutions present on phenyl parts. Molecular docking study were conducted of the optimized compounds (i.e., compound 4, 6, and 3 etc. using MOE default parameters), the results revealed that compound 4, 6, and 3 showed numerous key interactions with the target protein, which indicate the high potential of these compounds against the target compound. All these compounds were screened for cytotoxic activity against normal normal Vero cell line and found non-toxic.

Synthesis and biological activities of butyrylcholinesterase inhibitors

Acetylcholinesterase (AChE) inhibitor is the first choice for the treatment of Alzheimer's disease (AD), but it has some defects, such as dose limitation and unsatisfactory long-term treatment effect. Recent studies have shown that butyrylcholinesterase (BuChE) inhibitors or double acetyl and butyryl cholinesterase inhibitors have better curative effects on AD, and the side effects are lower than those of specific AChE inhibitors. Dual target cholinesterase inhibitors have become a new hotspot in the research of anti-AD drugs. Herein, the synthesis and bioactivities of BuChE inhibitors were reviewed.

The biological activities of butyrylcholinesterase inhibitors

Acetylcholinesterase (AChE) inhibitor is the first choice for the treatment of Alzheimer's disease (AD), but it has some defects, such as dose limitation and unsatisfactory long-term treatment effect. Recent studies have shown that butyrylcholinesterase (BuChE) inhibitors or double acetyl and butyryl cholinesterase inhibitors have better curative effects on AD, and the side effects are lower than those of specific AChE inhibitors. Dual target cholinesterase inhibitors have become a new hotspot in the research of anti-AD drugs. Herein, the synthesis and bioactivities of BuChE inhibitors were reviewed.

Novel metabolic enzyme inhibitors designed through the molecular hybridization of thiazole and pyrazoline scaffolds

New hybrid thiazolyl-pyrazoline derivatives (4a-k) were obtained through a facile and versatile synthetic procedure, and their inhibitory effects on the human carbonic anhydrase (hCA) isoforms I and II as well as on acetylcholinesterase (AChE) were determined. All new thiazolyl-pyrazolines showed activity at nanomolar levels as hCA I, hCA II, and AChE inhibitors, with K_I values in the range of 13.35-63.79, 7.01-115.80, and 17.89-48.05 nM, respectively. 1-[4-(4-Cyanophenyl)thiazol-2-yl]-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4f) and 1-(4-phenylthiazol-2-yl)-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4a) against hCAs and 1-[4-(4-chlorophenyl)thiazol-2-yl]-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4d) and 1-[4-(4-nitrophenyl)thiazol-2-yl]-3-(4-piperidinophenyl)-5-(4-fluorophenyl)-2-pyrazoline (4b) against AChE were identified as highly potent inhibitors, superior to the standard drugs, acetazolamide and tacrine, respectively. Compounds 4a-k were also evaluated for their cytotoxic effects on the L929 mouse fibroblast (normal) cell line. Moreover, a comprehensive ligand-receptor interaction prediction was performed using the ADME-Tox, Glide XP, and MM-GBSA modules of the Schrödinger Small-Molecule Drug Discovery Suite to elucidate the potential binding modes of the new hybrid inhibitors against these metabolic enzymes.

Tailored Modeling of Rivastigmine Derivatives as Dual Acetylcholinesterase and Butyrylcholinesterase Inhibitors for Alzheimer's Disease Treatment

Rational modification of known drug candidates to design more potent ones using computational methods has found application in drug design, development, and discovery. Herein, we integrate computational and theoretical methodologies to unveil rivastigmine derivatives as dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) for Alzheimer's disease (AD) management. The investigation entails pharmacokinetics screening, density functional theory (DFT) mechanistic study, molecular docking, and molecular dynamics (MD) simulation. We designed over 20 rivastigmine substituents, subject them to some analyses, and identified RL2 with an appreciable blood-brain barrier score and no permeability glycoprotein binding. The compound shows higher acylation energy and a favored binding affinity to the cholinesterase enzymes. RL2 interacts with the AChE and BuChE active sites showing values of -41.1/-39.5 kcal mol^-1 while rivastigmine binds with -32.7/-30.7 kcal mol^-1 for these enzymes. The study revealed RL2 (4-fluorophenyl rivastigmine) as a potential dual inhibitor for AChE and BuChE towards Alzheimer's disorder management.

Exploring indole-based-thiadiazole derivatives as potent acetylcholinesterase and butyrylcholinesterase enzyme inhibitors

Indole based thiadiazole derivatives (1-18) were synthesized and evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition. The IC₅₀ values of the synthesized analogues ranging between 0.17 ± 0.05 to 33.10 ± 0.6 μM against (AChE) and 0.30 ± 0.1 to 37.60 ± 0.6 μM against (BChE) enzymes. Among the series compounds 8 (IC₅₀ = 0.17 ± 0.05 μM) (IC₅₀ = 0.30 ± 0.1 μM), 9 (IC₅₀ = 0.30 ± 0.05 μM) (IC₅₀ = 0.60 ± 0.05 μM) and 10 (IC₅₀ = 1.30 ± 0.1 μM) (IC₅₀ = 2.60 ± 0.1) were found to be the most potent analogues bearing para, ortho, and meta-fluoro substitutions on phenyl ring attached to thiadiazole. In addition, all the synthesized scaffolds were characterized by using ¹H NMR, ¹³C NMR spectroscopy, and high-resolution Mass Spectrometry (HR-MS). To apprehend the binding mode of interaction of the most potent synthesized derivatives, a molecular docking study was performed.

Computational Studies on Acetylcholinesterase Inhibitors: From Biochemistry to Chemistry

Acetylcholinesterase inhibitors are the most promising therapeutics for Alzheimer's disease treatment as these prevent the loss of acetylcholine and slows the progression of the disease. The drugs approved for the management of Alzheimer's disease by the FDA are acetylcholinesterase inhibitors but are associated with side effects. Consistent and stringent efforts by the researchers with the help of computational methods opened new ways of developing novel molecules with good acetylcholinesterase inhibitory activity. In this manuscript, we reviewed the studies that identified the essential structural features of acetylcholinesterase inhibitors at the molecular level as well as the techniques like molecular docking, molecular dynamics, quantitative structure-activity relationship, virtual screening, and pharmacophore modelling that were used in designing these inhibitors.

Sulfur-containing therapeutics in the treatment of Alzheimer's disease

Sulfur is widely existent in natural products and synthetic organic compounds as organosulfur, which are often associated with a multitude of biological activities. OBenzothiazole, in which benzene ring is fused to the 4,5-positions of the thiazolerganosulfur compounds continue to garner increasing amounts of attention in the field of medicinal chemistry, especially in the development of therapeutic agents for Alzheimer's disease (AD). AD is a fatal neurodegenerative disease and the primary cause of age-related dementia posing severe societal and economic burdens. Unfortunately, there is no cure for AD. A lot of research has been conducted on sulfur-containing compounds in the context of AD due to their innate antioxidant potential and some are currently being evaluated in clinical trials. In this review, we have described emerging trends in the field, particularly the concept of multi-targeting and formulation of disease-modifying strategies. SAR, pharmacological targets, in vitro/vivo ADMET, efficacy in AD animal models, and applications in clinical trials of such sulfur compounds have also been discussed. This article provides a comprehensive review of organosulfur-based AD therapeutic agents and provides insights into their future development.

Synthesis, characterization, crystal structures, and the biological evaluation of 2-phenylthiazole derivatives as cholinesterase inhibitors

Four 2-phenylthiazole derivatives are synthesized, characterized, and evaluated as cholinesterase inhibitors. The structures of the 2-phenylthiazole derivatives are confirmed by 1H and 13C nuclear magnetic resonance spectroscopy, single-crystal X-ray diffraction studies, and Hirshfeld surfaces analysis. Hirshfeld surface analysis of the prepared compounds showed C–H···O intermolecular interactions. The cholinesterase inhibition activities of the synthesized compounds are tested by Ellman’s method. [2-(4-Benzyloxyphenyl)-thiazol-4-yl]-(3,5-dimethylpiperidin-1-yl)-methanone showed the best acetylcholinesterase inhibition activity with an IC50 value of 8.86 µM and the best butyrylcholinesterase inhibition activity with an IC50 value of 1.03 µM. A docking study demonstrates that the same compound interacts with the catalytic anionic site and peripheral anionic site of acetylcholinesterase and the catalytic anionic site of butyrylcholinesterase.

Multi-target approach for Alzheimer's disease treatment: computational biomolecular modeling of cholinesterase enzymes with a novel 4-N-phenylaminoquinoline derivative reveal promising potentials

The identification of dual inhibitors targeting the active sites of the cholinesterase enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), have lately surfaced as a multi-approach towards Alzheimer treatment. More recently, a novel series of 4-N-phenylaminoquinolines was synthesized and evaluated against AChE and BuChE in which one of the compounds displayed appreciable inhibition compared to the standard compound, galantamine. To provide a clearer picture of the inhibition mechanism of this potent compound at the molecular level, computational biomolecular modeling was carried out. The investigation was initiated with the exploration of the chemical properties of the identified compound 11 b and reference drug, galantamine. Density functional theory (DFT) calculations reveal some conceptual parameters that provide information on the stability and reactivity of the compounds as potential inhibitors. To unveil the binding mechanism, energetics and enzyme-ligand interactions, molecular dynamics (MD) simulations of six different systems were executed over a period. Calculated binding free energy values are in the same order with experimental IC₅₀ data. Identification of the main residues driving optimum binding of the active compound 11 b to the binding region of both AChE and BuChE showed Trp81 and Trp110 as the most important, respectively. It was proposed that the studied compound could serve as a dual inhibitor for AChE and BuChE, therefore, would potentially be a promising moiety in a multi-target approach for the treatment of Alzheimer's disorder.Communicated by Ramaswamy H. Sarma.

A Multi-layered Variable Selection Strategy for QSAR Modeling of Butyrylcholinesterase Inhibitors

Background:

Alzheimer’s disease (AD), a neurological disorder, is the most common cause of senile dementia. Butyrylcholinesterase (BuChE) enzyme plays a vital role in regulating the brain acetylcholine (ACh) neurotransmitter, but in the case of Alzheimer’s disease (AD), BuChE activity gradually increases in patients with a decrease in the acetylcholine (ACh) concentration via hydrolysis. ACh plays an essential role in regulating learning and memory as the cortex originates from the basal forebrain, and thus, is involved in memory consolidation in these sites.

Methods:

In this work, we have developed a partial least squares (PLS)-regression based two dimensional quantitative structure-activity relationship (2D-QSAR) model using 1130 diverse chemical classes of compounds with defined activity against the BuChE enzyme. Keeping in mind the strict Organization for Economic Co-operation and Development (OECD) guidelines, we have tried to select significant descriptors from the large initial pool of descriptors using multi-layered variable selection strategy using stepwise regression followed by genetic algorithm (GA) followed by again stepwise regression technique and at the end best subset selection prior to development of final model thus reducing noise in the input. Partial least squares (PLS) regression technique was employed for the development of the final model while model validation was performed using various stringent validation criteria.

Results:

The results obtained from the QSAR model suggested that the quality of the model is acceptable in terms of both internal (R2= 0.664, Q2= 0.650) and external (R2 Pred= 0.657) validation parameters. The QSAR studies were analyzed, and the structural features (hydrophobic, ring aromatic and hydrogen bond acceptor/donor) responsible for enhancement of the activity were identified. The developed model further suggests that the presence of hydrophobic features like long carbon chain would increase the BuChE inhibitory activity and presence of amino group and hydrazine fragment promoting the hydrogen bond interactions would be important for increasing the inhibitory activity against BuChE enzyme.

Conclusion:

Furthermore, molecular docking studies have been carried out to understand the molecular interactions between the ligand and receptor, and the results are then correlated with the structural features obtained from the QSAR models. The information obtained from the QSAR models are well corroborated with the results of the docking study.

Anticholinesterase Activity of Cinnamic Acids Derivatives: In Vitro, In Vivo Biological Evaluation, and Docking Study

Background:

Acetylcholine deficiency in the hippocampus and cortex, aggregation of amyloid-beta, and beta-secretase overactivity have been introduced as the main reasons in the formation of Alzheimer’s disease.

Objective:

A new series of cinnamic derived acids linked to 1-benzyl-1,2,3-triazole moiety were designed, synthesized, and evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities.

Methods:

Colorimetric Ellman’s method was used for the determination of IC50% of AchE and BuChE inhibitory activity. The kinetic studies, neuroprotective activity, BACE1 inhibitory activity, evaluation of inhibitory potency on Aβ1-42 self-aggregation induced by AchE, and docking study were performed for studying the mechanism of action.

Results:

Some of the synthesized compounds, compound 7b-4 ((E)-3-(3,4-dimethoxyphenyl)-N-((1- (4-fluorobenzyl)-1H-1,2,3-triazole-4-yl) methyl) acrylamide) depicted the most potent acetylcholinesterase inhibitory activities ( IC50 = 5.27 μM ) and compound 7a-1 (N- ( (1- benzyl- 1H- 1, 2, 3- triazole - 4-yl) methyl) cinnamamide) demonstrated the most potent butyrylcholinesterase inhibitory activities (IC50 = 1.75 μM). Compound 7b-4 showed neuroprotective and β-secretase (BACE1) inhibitory activitiy. In vivo studies of compound 7b-4 in Scopolamine-induced dysfunction confirmed memory improvement.

Conculusion:

It should be noted that molecular modeling (compounds 7b-4 and 7a-1) and kinetic studies (compounds 7a-1 and 7b-4) showed that these synthesis compounds interacted simultaneously with both the catalytic site (CS) and peripheral anionic site (PAS) of AChE and BuChE.

Synthesis, in vitro urease inhibitory potential and molecular docking study of benzofuran-based-thiazoldinone analogues

In continuation of our work on enzyme inhibition, the benzofuran-based-thiazoldinone analogues (1-14) were synthesized, characterized by HREI-MS, 1H and 13CNMR and evaluated for urease inhibition. Compounds 1-14 exhibited a varying degree of urease inhibitory activity with IC50 values between 1.2 ± 0.01 to 23.50 ± 0.70 µM when compared with standard drug thiourea having IC50 value 21.40 ± 0.21 µM. Compound 1, 3, 5 and 8 showed significant inhibitory effects with IC50 values 1.2 ± 0.01, 2.20 ± 0.01, 1.40 ± 0.01 and 2.90 ± 0.01 µM respectively, better than the rest of the series. A structure activity relationship (SAR) of this series has been established based on electronic effects and position of different substituents present on phenyl ring. Molecular docking studies were performed to understand the binding interaction of the compounds.