The recent development of donepezil structure-based hybrids as potential multifunctional anti-Alzheimer's agents: highlights from 2010 to 2020

In Situ Biomineralization and Citric Acid Etching Strategy for Enhancing Activity of Immobilized Acetylcholinesterase

Enhancing the structural stability of an enzyme and maintaining its catalytic activity are effective ways to improve enzyme utilization and reduce the cost of drug screening. However, immobilized enzyme activity tends to decrease in existing immobilization techniques due to conformational changes and microenvironmental restrictions. In this paper, we present a facile approach to prepare immobilized acetylcholinesterase (AChE) with high activity by a ZIF-8 in situ immobilization and citric acid (CA) etching strategy. CA breaks the coordination bond of ZIF-8 and produces defects, expanding the pore space, improving substrate accessibility, and fully exposing the active site of the enzyme. The enhancement of the catalytic activity of AChE@ZIF-8-CA was about 6.10-fold compared with the free enzyme. In addition, AChE@ZIF-8-CA exhibited an excellent encapsulation efficiency and good tolerance to temperature, pH, and organic solvents. The relative activity remains at the initial 83.77% even in five repeated experiments. The strategy provides a novel and efficient way to quickly construct highly active immobilized enzymes under mild conditions.

Recent Advances in Medicinal Chemistry of Memantine Against Alzheimer's Disease

Alzheimer's disease (AD) is a chronic progressive, age-related neurodegenerative brain disorder characterized by the irreversible decline of memory and other cognitive functions. It is one of the major health threat of the 21st century, which affects around 60% of the population over the age of 60 years. The problem of this disease is even more major because the existing pharmacotherapies only provide symptomatic relief without addressing the basic factors of the disease. It is characterized by the extracellular deposition of amyloid β (Aβ) to form senile plaques, and the intracellular hyperphosphorylation of tau to form neurofibrillary tangles (NFTs). Due to the complex pathophysiology of this disease, various hypotheses have been proposed, including the cholinergic, Aβ, tau, oxidative stress, and the metal-ion hypothesis. Among these, the cholinergic and Aβ hypotheses are the primary targets for addressing AD. Therefore, continuous advances have been made in developing potential cholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists to delay disease progression and restore cholinergic neurotransmission. In this review article, we tried to comprehensively summarize the recent advancement in NMDA receptor antagonist (memantine) and their hybrid analogs as potential disease-modifying agents for the treatment of AD. Furthermore, we also depicted the design, rationale, and SAR analysis of the memantine-based hybrids used in the last decade for the treatment of AD.

A Series of Novel 1-H-isoindole-1,3(2H)-dione Derivatives as Acetylcholinesterase and Butyrylcholinesterase Inhibitors: In Silico, Synthesis and In Vitro Studies

The derivatives of isoindoline-1,3-dione are interesting due to their biological activities, such as anti-inflammatory and antibacterial effects. Several series have been designed and evaluated for Alzheimer's therapy candidates. They showed promising activity. In this work, six new derivatives were first tested in in silico studies for their inhibitory ability against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. Molecular docking and molecular dynamic simulation were applied. Next, these compounds were synthesized and characterized by 1H NMR, 13C NMR, FT-IR, and ESI-MS techniques. For all imides, the inhibitory activity against AChE and BuChE was tested using Ellaman's method. IC50 values were determined. The best results were obtained for the derivative I, with a phenyl substituent at position 4 of piperazine, IC50 = 1.12 μM (AChE) and for the derivative III, with a diphenylmethyl moiety, with IC50 = 21.24 μM (BuChE). The compounds tested in this work provide a solid basis for further structural modifications, leading to the effective design of potential inhibitors of both cholinesterases.

Development of novel 9H-carbazole-4H-chromene hybrids as dual cholinesterase inhibitors for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease affecting mental ability and neurocognitive functions. Cholinesterase enzymes affect concentration of acetylcholine in the brain, leading to dementia. Thus, there is an urgent need to develop novel dual cholinesterase inhibitors as possible anti-AD drugs. Herein, we have designed and synthesized a novel series of 9H-carbazole-4H-chromenes 4(a-l) through a one-pot three-component reaction of salicylaldehydes (1), hydroxycarbazole (2) and N-methyl-1-(methylthio)-2-nitroethenamine (3) using triethylamine as a catalyst in ethanol. Synthetic transformation involves the formation of two C-C bonds and one C-O bond in a single step to obtain desired analogs. The rapid one-pot reaction does not require chromatographic purification, proceeds under mild conditions, and exhibits good tolerance toward various functional groups with high synthetic yields. Synthesized compounds were screened for cytotoxicity using MTT assay in BV-2 microglial cells. These compounds were then in-vitro screened against acetylcholinesterase (AChE) and butyrylcholinestrase (BuChE) enzymes. Most of these ligands have shown dual cholinesterase inhibitory activity compared to the standard drug. In-vitro results showed that the compounds 4a and 4d have promising anticholinesterase response against both cholinesterase enzymes (4a, AChE IC50: 5.76 µM, BuChE IC50: 48.98 µM; 4d, AChE IC50: 3.58 µM, BuChE IC50: 42.73 µM). In-vitro results were validated by molecular docking and dynamic simulation at 100 ns. Molecular docking and molecular dynamics simulation study strongly supported structural features present in these analogs. Together, these analogs could be exploited to develop dual anti-cholinesterase candidates to treat AD in combination with other drugs.

In Silico Investigation of Novel Compounds as Inhibitors of Acetylcholinesterase Enzyme for the Treatment of Alzheimer's Diseases

Alzheimer's disease (AD) is a "progressive, neurodegenerative disease that occurs when nerve cells in the brain die." There are only 4 drugs approved by the United States Food and Drug Administration (FDA). Three (donepezil, rivastigmine, and galantamine) out of these four drugs are anticholinesterase inhibitors, while the fourth one memantine is an N-methyl-D-aspartate (NMDA) receptor inhibitor. Currently, two immunotherapy drugs that target amyloid protein (donanemab and lecanemab) are being considered for the treatment of Alzheimer's disease at an early stage. All these drug molecules are still not the complete answer to the treatment of Alzheimer's disease. A recent report from the Office of National Statistics showed that AD is the leading cause of death in 2022. Therefore, there is an urgency to develop more drugs that can treat AD. Based on this urgency, we aim to investigate how bioactive and already approved drugs could be repurposed for inhibiting the anticholinesterase enzyme using computational studies. To achieve this, the data science tool-Python coding was compiled on Jupyter Notebook to mine bioactive compounds from the ChEMBL database. The most bioactive compounds obtained were further investigated using Molecular Operating Environment (MOE) software to carry out molecular docking and ligand analysis, and this was followed by molecular dynamics simulation production at 35 ns using GROMACS 2022.4 on Archer 2 machine. The molecular dynamic analysis was carried out using HeroMDanalysis software. Data mining of the ChEMBL database was carried out for lipase inhibitors, and this gave CHEMBL-ID 1240685, a peptide molecule, the most active compound at the time of data mining. Further literature studies gave Zoladex an FDA-approved drug for the treatment of breast cancer as another compound of interest. The in silico studies were carried out against the anticholinesterase enzyme using two FDA-approved drugs donepezil and galantamine as a template for comparing the in silico activities of the repurposed drugs. A very useful receptor for this study was PDB-1DX6, a cocrystallized galantamine inhibitor of acetylcholinesterase enzyme. The molecular docking analysis (using ligand interactions) and molecular dynamic analysis (root mean square deviation (RMSD) and root mean square fluctuation (RMSF)) showed that the two peptide molecules CHEMBL-1240685 and Zoladex gave the best binding energy and stability when compared to the FDA-approved drugs (donepezil and galantamine). Finally, further literature studies revealed that Zoladex affects memory reduction; therefore, it was dropped as a possible repurposed drug. Our research showed that CHEMBL-1240685 is a potential compound that could be investigated for the inhibition of anticholinesterase enzyme and might be another drug molecule that could be used to treat Alzheimer's disease.

Rational design for novel heterocyclic based Donepezil analogs for Alzheimer's disease: an in silico approach

Alzheimer's disease (AD) is a progressive neurodegenerative disease and has devastating impacts on the elderly population. During the last two decades, there has been a significant focus on developing effective and safe treatments for AD. Acetylcholinesterase (AChE) has been identified as one of the primary therapeutic targets for developing drug candidates for AD. However, there is still a need for more efficient therapies. In this study, our aim is to design a new series of heterocyclic-based AChE inhibitors inspired by a standard drug. Here, we carried out molecular docking, drug-likeliness characteristics, and molecular dynamics (MD) to predict important pharmacophore features and understand the inhibitory mechanism of the designed inhibitors towards the AChE. We have designed 112 new derivatives by replacing the piperidine moiety of Donepezil with the different five and six-membered heterocyclic rings and selected 15 compounds that show higher or comparable docking scores as compared to standard Donepezil and pose no risk for carcinogenicity. Furthermore, MD results imply the structural stability of the selected docked complexes and seven exhibit a stronger binding affinity towards the AChE than Donepezil. Thus, heterocyclic-based derivatives based on oxazole, pyrazole, and tetrahydropyran may be potential therapeutic candidates for AD. Our structure-based drug design approach allows us to identify and gain insight into the structural stability of the inhibitor-protein complex and the inhibition mechanism of the newly designed inhibitors. The present finding might be an initial selection for developing a new inhibitor for AD and provide a direction for further experiments on its biological activities.Communicated by Ramaswamy H. Sarma.

Sulfonamide Derivatives: Recent Compounds with Potent Anti-alzheimer's Disease Activity

Facile synthetic procedures and broad spectrum of biological activities are special attributes of sulfonamides. Sulfonamide derivatives have demonstrated potential as a class of compounds for the treatment of Alzheimer's disease (AD). Recent sulfonamide derivatives have been reported as prospective anti-AD agents, with a focus on analogues that significantly inhibit the function of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes and exhibit remarkable antioxidant and anti-inflammatory properties, all of which are critical for the treatment of AD. Sulfonamide- mediated activation of nuclear factor erythroid 2-related factor 2 (NRF2), a key regulator of the endogenous antioxidant response, has also been suggested as a potential therapeutic approach in AD. Additionally, it has been discovered that a number of sulfonamide derivatives show selectivity for the β- and γ-secretase enzymes and a significant reduction of amyloid B (Aβ) aggregation, which have been implicated in AD. The comparative molecular docking of benzenesulfonamide and donepezil, an AD reference drug showed comparable anti-AD activities. These suggest that sulfonamide derivatives may represent a new class of drugs for the treatment of AD. Thus, the current review will focus on recent studies on the chemical synthesis and evaluation of the anti-AD properties, molecular docking, pharmacological profile, and structure-activity relationship (SAR) of sulfonamide derivatives, as well as their potential anti-AD mechanisms of action. This paper offers a thorough assessment of the state of the art in this field of study and emphasizes the potential of sulfonamide derivatives synthesized during the 2012-2023 period as a new class of compounds for the treatment of AD.

Synthesis, biological evaluation, and computational studies of N-benzyl pyridinium-curcumin derivatives as potent AChE inhibitors with antioxidant activity

A library of N-benzylpyridinium-based compounds, 7a-j and 8a-j, was designed and synthesised as potential acetylcholinesterase) AChE (inhibitors. An in vitro assay for the synthesised compounds showed that most compounds had significant AChE inhibitory activities at the nanomolar and submicromolar levels. The benzyl (8a) and fluoro (8b) derivatives were the most active, with IC50 values ≤56 nM. Compound 7f, which had a benzyl moiety, showed the highest potency among all the target compounds, with an IC50 value of 7.5 ± 0.19 nM against AChE, which was higher than that of the activities of tacrine (IC50 = 30 ± 0.2 nM) and donepezil (IC50 = 14 ± 0.12 nM). Compounds with vanillin moieties exhibited antioxidant activity. Among the tested compounds, four derivatives (7f, 7 g, 8f, and 8 g) exhibited superior AChE inhibitory activity, with Ki values of 6-16 nM, which were potent in the same range as the approved drug, donepezil. These compounds showed moderate antioxidant activities, as indicated by the results of the ABTS assay.

The 3-(3-oxoisoindolin-1-yl)pentane-2,4-dione (ISOAC1) as a new molecule able to inhibit Amyloid β aggregation and neurotoxicity

Amyloid β 1-42 (Aβ1-42) protein aggregation is considered one of the main triggers of Alzheimer's disease (AD). In this study, we examined the in vitro anti-amyloidogenic activity of the isoindolinone derivative 3-(3-oxoisoindolin-1-yl)pentane-2,4-dione (ISOAC1) and its neuroprotective potential against the Aβ1-42 toxicity. By performing the Thioflavin T fluorescence assay, Western blotting analyses, and Circular Dichroism experiments, we found that ISOAC1 was able to reduce the Aβ1-42 aggregation and conformational transition towards β-sheet structures. Interestingly, in silico studies revealed that ISOAC1 was able to bind to both the monomer and a pentameric protofibril of Aβ1-42, establishing a hydrophobic interaction with the PHE19 residue of the Aβ1-42 KLVFF motif. In vitro analyses on primary cortical neurons showed that ISOAC1 counteracted the increase of intracellular Ca2+ levels and decreased the Aβ1-42-induced toxicity, in terms of mitochondrial activity reduction and increase of reactive oxygen species production. In addition, confocal microscopy analyses showed that ISOAC1 was able to reduce the Aβ1-42 intraneuronal accumulation. Collectively, our results clearly show that ISOAC1 exerts a neuroprotective effect by reducing the Aβ1-42 aggregation and toxicity, hence emerging as a promising compound for the development of new Aβ-targeting therapeutic strategies for AD treatment.

Exploration of the novel phthalimide-hydroxypyridinone derivatives as multifunctional drug candidates against Alzheimer's disease

A novel series of phthalimide-hydroxypyridinone derivatives were rationally designed and evaluated as potential anti-Alzheimer's disease (AD) agents. Bioactivity tests showed that all compounds displayed great iron ions-chelating activity (pFe3+ = 17.07-19.52), in addition to potent inhibition of human monoamine oxidase B (hMAO-B). Compound 11n emerged as the most effective anti-AD lead compound with a pFe3+ value of 18.51, along with selective hMAO-B inhibitory activity (IC50 = 0.79 ± 0.05 μM, SI > 25.3). The results of cytotoxicity assays demonstrated that 11n showed extremely weak toxicity in PC12 cell line at 50 μM. Additionally, compound 11n displayed a cytoprotective effect against H2O2-induced oxidative damage. Moreover, compound 11n exhibited ideal blood-brain barrier (BBB) permeability in the parallel artificial membrane permeation assay (PAMPA), and significantly improved scopolamine-induced cognitive and memory impairment in mice behavioral experiments. In conclusion, these favorable experimental results suggested compound 11n deserved further investigation as an anti-AD lead compound.

Piperidine: A Versatile Heterocyclic Ring for Developing Monoamine Oxidase Inhibitors

The monoamine oxidase enzyme (MAO), which is bound on the membrane of mitochondria, catalyzes the oxidative deamination of endogenous and exogenous monoamines, including monoamine neurotransmitters such as serotonin, adrenaline, and dopamine. These enzymes have been proven to play a significant role in neurodegeneration; thus, they have recently been researched as prospective therapeutic targets for neurodegenerative illness treatment and management. MAO inhibitors have already been marketed as neurodegeneration illness treatments despite their substantial side effects. Hence, researchers are concentrating on developing novel molecules with selective and reversible inhibitory properties. Piperine, which is a phytochemical component present in black pepper, has been established as a potent MAO inhibitor. Piperine encompasses a piperidine nucleus with antibacterial, anti-inflammatory, antihypertensive, anticonvulsant, antimalarial, antiviral, and anticancer properties. The current Review focuses on the structural changes and structure-activity relationships of piperidine derivatives as MAO inhibitors.

Voglibose attenuates cognitive impairment, Aβ aggregation, oxidative stress, and neuroinflammation in streptozotocin-induced Alzheimer's disease rat model

Alzheimer's disease (AD) is an age-dependent neurodegenerative disease hallmarked by Amyloid-β (Aβ) aggregation, cognitive impairment, and neuronal and synaptic loss. In this study, AD was induced in male Wistar rats (n = 6) by the administration of intracerebroventricular-streptozotocin (ICV-STZ-3 mg/kg/day), and Voglibose (Vog) was administered at various doses (10, 25, and 50 mg/kg), while Galantamine (3 mg/kg) acted as a reference standard drug. Behavioral alterations in both spatial and non-spatial memory functions were evaluated in the experimental rats. At the end of the study, all experimental rats were sacrificed, and their brain parts, the cortex and hippocampus, were subjected to biochemical, western blot, and histopathological analysis. In our study results, the statistically significant dose-dependent results from the behavioral tests show the Voglibose-treated groups significantly improved (p < 0.0001) spatial and non-spatial memory functions when compared with ICV-STZ-treated group. Meanwhile, when compared with ICV-STZ-treated rats, treatment with Voglibose (10, 25, and 50 mg/kg) showed the activities of both acetylcholinesterase (AChE) and malondialdehyde (MDA) were significantly attenuated (p < 0.0001), while the operation of antioxidant enzymes was considerably enhanced (p < 0.0001). The molecular estimation showed that it significantly attenuates (p < 0.0001) the TNF-α, IL-1β, and CRP activity, and the western blot results demonstrate the significantly attenuated Aβ aggregation. The histopathological results showed that the Voglibose treatment had an effective improvement in clear cytoplasm and healthy neuronal cells. In conclusion, our results suggest that Voglibose has potent neuroprotective effects against the ICV-STZ-induced AD model. Furthermore, these results support the possibility of Voglibose as a therapeutic approach to improving cognitive function, suggesting that controlling Aβ aggregation might be a novel target for the development of AD.

Molecular docking and toxicity studies of nerve agents against acetylcholinesterase (AChE)

Acetylcholinesterase (AChE) is a cholinergic enzyme that plays an essential role in the autonomic nervous system. This enzyme is often the target of many nerve agents. When this enzyme is inhibited, its function to hydrolyze acetylcholine is stopped, accumulating the acetylcholine in the tissue and causing prolonged stimulation. Some of the significant nerve agents include sarin (GB), soman (GD), tabun (GA), and venomous agent (VX). In order to determine which compound is the most stable and has the best affinity, the nerve agent venomous agent (VX), sarin (GB), soman (GD), and tabun (GA) are docked to the acetylcholinesterase (AChE) enzyme. After that, toxicity tests will be performed on 17 targets for the compound that was chosen. Autodock Vina 1.2.0 is the software used for the docking procedure. should use the Pymol program version 2.5.4 for analysis and the Ligplot software version 2.2 for visualization of the docking findings. The 'Tox Prediction' algorithm from Insilico was used to determine the toxicity of various substances. Based on the results of molecular docking, the free binding energy of Donepezil, sarin (GB), soman (GD), tabun (GA), and venomous agent (VX) in kcal/mol are -12,3, -4.8, -6.0, -5,1, and -6.3 respectively. Finally, four ligands bind strongly to the receptor Donepezil at RMSD 0.327 Å, and the venomous agent (VX) compound binds the most strongly compared to the other test ligands. Furthermore, in the toxicity test of Compound VX, which exhibits neurotoxic activity, no toxic activity was observed on specific organs and targets.

Design, Synthesis, and Biological Activity of Donepezil: Aromatic Amine Hybrids as Anti-Alzheimerss Drugs

In this study, benzylpiperidine, the active group of donepezil (DNP), was connected with the neurotransmitter phenylethylamine by square amide, in which the fat chain of phenylethylamine was reduced and the benzene rings were substituted. A series of multifunctional hybrid compounds, including DNP-aniline hybrids (1-8), DNP-benzylamine hybrids (9-14), and DNP-phenylethylamine hybrids (15-21) were obtained and their cholinesterase inhibitory activity and neuroprotection of the SH-SY5Y cell line were determined. Results showed that compound 3 exhibited excellent acetylcholinesterase inhibitory activity with an IC₅₀ value of 4.4 μM, higher than that of positive control DNP and significant neuroprotective effects against H₂O₂-induced oxidative damage in SH-SY5Y cells with 80.11% viability rate at 12.5 μM, much higher than that of the model group (viability rate = 53.1%). The mechanism of action of compound 3 was elucidated by molecular docking, reactive oxygen species (ROS), and immunofluorescence analysis. The results suggest that compound 3 could be further explored as a lead compound for the treatment of Alzheimer's disease. In addition, molecular docking research indicated that the square amide group formed strong interactions with the target protein. Based on the above analysis, we believe that square amide could be an interesting construction unit in anti-AD agents.

New indole derivatives as multitarget anti-Alzheimer's agents: synthesis, biological evaluation and molecular dynamics

Background: Alzheimer's disease is a neurological disorder that causes brain cells to shrink and die. Aim: Thirteen novel 'oxathiolanyl', 'pyrazolyl' and 'pyrimidinyl' indole derivatives were designed and synthesized as anti-Alzheimer's disease treatment. Method: In vitro enzyme assay was performed against both AChE and BChE enzymes. In addition, antioxidant assay and cytotoxicity on a normal cell line were determined. Molecular docking and dynamic simulations were conducted to confirm the binding mode in both esterases' active sites. In silico absorption, distribution, metabolism, excretion and toxicity studies were also carried out. Results & conclusion: Compounds 5, 7 and 11 exhibited superior inhibitory activity against acetylcholinesterase and butyrylcholinesterase, with IC₅₀ values of 0.042 and 3.003 μM, 2.54 and 0.207 μM and 0.052 and 2.529 μM, respectively, compared with donepezil.

Investigating the chemical profile of Rheum lhasaense and its main ingredient of piceatannol-3'-O-β-D-glucopyranoside on ameliorating cognitive impairment

Rheum lhasaense A. J. Li et P. K. Hsiao, a stout herb plant from the Polygonaceae, is a typical Tibetan folk herb with heat-clearing and detoxifying effects, but does not have the typical laxative effect compared with other rhubarb plants. Nevertheless, its chemical composition and pharmacological activities still lack in-depth research. The present study endeavored to analyze the possible phytochemical constituents in R. lhasaense and explore the main compound piceatannol-3'-O-β-D-glucopyranoside (PG) effect on cognitive impairment and its underlying mechanism. The chemical profile of R. lhasaense discovered 46 compounds, including 27 stilbenoids and 13 gallotannins using UPLC-Q-TOF-MS/MS. The UPLC determined the contents of 6 main stilbenoids, among which the content of PG was the highest, up to 61.06 mg/g. Moreover, behavioral tests showed that PG (40 mg/kg and 160 mg/kg) administration markedly ameliorated memory impairments of scopolamine-induced mice. Biochemical parameters showed that PG treatment alleviated the levels of Ach, AchE, and inflammatory factors while elevating the levels of antioxidants in mice. In addition, network pharmacology was performed to reveal PG exert an mild cognitive impairment effect by participating in neurodegenerative disease pathways, proliferation and apoptosis-, and inflammation-related pathways. Eventually, the results of molecular docking and the qRT-PCR revealed that PG down-regulated the mRNA expressions of MMP3, MMP9 and BACE1 in cognitive impairment mice brain tissue. In conclusion, our results demonstrated that PG mitigated scopolamine-induced cognitive dysfunction in mice by targeting the BACE1-MMP3/9 pathway, and PG might be a promising mild AD drug candidate.

Correlating the charge transfer efficiency of metallic sulfa-isatins to design efficient NLO materials with better drug designs

The present study presents synthesis, characterization and first principle studies on metal chelates, (1-12), of sulfonamide-isatin reacted ligands (S¹-S³). All the products were evaluated by various physical and spectral (UV, IR, NMR, MS) means. The octahedral geometry for Co⁺², Ni⁺² and Zn⁺², while square planner geometry for Cu⁺² chelates were confirmed by their spectroscopic and magnetic data. Their physical chemistry investigation show the ability of aromatic rings to stabilize sulfonamide rings across NH-π interactions at their optimized geometries. The nonlinear optical response for all the compounds disclosed that the z-axis has the most contributions. An efficient electron injection and hole studies for Au and Al electrodes having the energies of - 0.1-3.1 and 0.0-11.8 eV respectively were noted. Their bioactive character was shown by global reactivity calculated from FMO energy gaps. The enzyme inhibitory results were found to be 45-61% and IC₅₀ = 102-122 µL, for compound (4), (10), (8), (5) and (12) against the amylase, protease, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) respectively The antibacterial findings showed significant action having 11-17 mm for (2), (7) and (10) for bacterial species, Escherichia coli and Micrococcus luteus. The DPPH and ferric reducing power assay was used to evaluate the antioxidant capacity with 49.0 ± 0.09-66.2 ± 0.08% and IC₅₀ = 102.3-122.4 µL range. In comparison to ligands, the results showed that all metal chelates had higher bioactivity. The chelation was the primary cause of their increased bioactivity. These findings suggested that such metal-based compounds might be used as antimicrobial, and antioxidant options in future to cope drug resistance.

5-Aryl-1,3,4-oxadiazol-2-amines Decorated with Long Alkyl and Their Analogues: Synthesis, Acetyl- and Butyrylcholinesterase Inhibition and Docking Study

2,5-Disubstituted 1,3,4-oxadiazoles are privileged versatile scaffolds in medicinal chemistry that have exhibited diverse biological activities. Acetyl- (AChE) and butyrylcholinesterase (BChE) inhibitors are used, e.g., to treat dementias and myasthenia gravis. 5-Aryl-1,3,4-oxadiazoles decorated with dodecyl linked via nitrogen, sulfur or directly to this heterocycle have been designed as potential inhibitors of AChE and BChE. They were prepared from commercially available or in-house prepared hydrazides by reaction with dodecyl isocyanate to form hydrazine-1-carboxamides 2 (yields 67–98%) followed by cyclization using p-toluenesulfonyl chloride and triethylamine in 41–100% yields. Thiadiazole isostere was also synthesized. The derivatives were screened for inhibition of AChE and BChE using Ellman’s spectrophotometric method. The compounds showed a moderate dual inhibition with IC₅₀ values of 12.8–99.2 for AChE and from 53.1 µM for BChE. All the heterocycles were more efficient inhibitors of AChE. The most potent inhibitor, N-dodecyl-5-(pyridin-4-yl)-1,3,4-thiadiazol-2-amine 3t, was subjected to advanced reversibility and type of inhibition evaluation. Structure–activity relationships were identified. Many oxadiazoles showed lower IC₅₀ values against AChE than established drug rivastigmine. According to molecular docking, the compounds interact non-covalently with AChE and BChE and block entry into enzyme gorge and catalytic site, respectively.