Synthesis, biological evaluation, molecular docking, and MD simulation of novel 2,4-disubstituted quinazoline derivatives as selective butyrylcholinesterase inhibitors and antioxidant agents.

Alzheimer's disease is the most prevalent neurodegenerative disorder characterized by significant memory loss and cognitive impairments. Studies have shown that the expression level and activity of the butyrylcholinesterase enzyme increases significantly in the late stages of Alzheimer's disease, so butyrylcholinesterase can be considered as a promising therapeutic target for potential Alzheimer's treatments. In the present study, a novel series of 2,4-disubstituted quinazoline derivatives (6a-j) were synthesized and evaluated for their inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinestrase (BuChE) enzymes, as well as for their antioxidant activities. The biological evaluation revealed that compounds 6f, 6h, and 6j showed potent inhibitory activities against eqBuChE, with IC50 values of 0.52, 6.74, and 3.65 µM, respectively. These potent compounds showed high selectivity for eqBuChE over eelAChE. The kinetic study demonstrated a mixed-type inhibition pattern for both enzymes, which revealed that the potent compounds might be able to bind to both the catalytic active site and peripheral anionic site of eelAChE and eqBuChE. In addition, molecular docking studies and molecular dynamic simulations indicated that potent compounds have favorable interactions with the active sites of BuChE. The antioxidant screening showed that compounds 6b, 6c, and 6j displayed superior scavenging capabilities compared to the other compounds. The obtained results suggest that compounds 6f, 6h, and 6j are promising lead compounds for the further development of new potent and selective BuChE inhibitors.

Cholinesterase Inhibition and Antioxidative Capacity of New Heteroaromatic Resveratrol Analogs: Synthesis and Physico-Chemical Properties.

The targeted compounds in this research, resveratrol analogs 1-14, were synthesized as mixtures of isomers by the Wittig reaction using heterocyclic triphenylphosphonium salts and various benzaldehydes. The planned compounds were those possessing the trans-configuration as the biologically active trans-resveratrol. The pure isomers were obtained by repeated column chromatography in various isolated yields depending on the heteroaromatic ring. It was found that butyrylcholinesterase (BChE) was more sensitive to the heteroaromatic resveratrol analogs than acetylcholinesterase (AChE), except for 6, the methylated thiophene derivative with chlorine, which showed equal inhibition toward both enzymes. Compounds 5 and 8 achieved the highest BChE inhibition with IC50 values of 22.9 and 24.8 µM, respectively. The same as with AChE and BChE, methylated thiophene subunits of resveratrol analogs showed better enzyme inhibition than unmethylated ones. Two antioxidant spectrophotometric methods, DPPH and CUPRAC, were applied to determine the antioxidant potential of new heteroaromatic resveratrol analogs. The molecular docking of these compounds was conducted to visualize the ligand-active site complexes' structure and identify the non-covalent interactions responsible for the complex's stability, which influence the inhibitory potential. As ADME properties are crucial in developing drug product formulations, they have also been addressed in this work. The potential genotoxicity is evaluated by in silico studies for all compounds synthesized.

Synthesis of novel aryl-substituted 2-aminopyridine derivatives by the cascade reaction of 1,1-enediamines with vinamidinium salts to develop novel anti-Alzheimer agents.

Alzheimer's disease (AD), a severe neurodegenerative disorder, imposes socioeconomic burdens and necessitates innovative therapeutic strategies. Current therapeutic interventions are limited and underscore the need for novel inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), enzymes implicated in the pathogenesis of AD. In this study, we report a novel synthetic strategy for the generation of 2-aminopyridine derivatives via a two-component reaction converging aryl vinamidinium salts with 1,1-enediamines (EDAMs) in a dimethyl sulfoxide (DMSO) solvent system, catalyzed by triethylamine (Et3N). The protocol introduces a rapid, efficient, and scalable synthetic pathway, achieving good to excellent yields while maintaining simplistic workup procedures. Seventeen derivatives were synthesized and subsequently screened for their inhibitory activity against AChE and BChE. The most potent derivative, 3m, exhibited an IC50 value of 34.81 ± 3.71 µM against AChE and 20.66 ± 1.01 µM against BChE compared to positive control donepezil with an IC50 value of 0.079 ± 0.05 µM against AChE and 10.6 ± 2.1 µM against BChE. Also, detailed kinetic studies were undertaken to elucidate their modes of enzymatic inhibition of the most potent compounds against both AChE and BChE. The promising compound was then subjected to molecular docking and dynamics simulations, revealing significant binding affinities and favorable interaction profiles against AChE and BChE. The in silico ADMET assessments further determined the drug-like properties of 3m, suggesting it as a promising candidate for further pre-clinical development.

New Heterostilbene and Triazole Oximes as Potential CNS-Active and Cholinesterase-Targeted Therapeutics.

New furan, thiophene, and triazole oximes were synthesized through several-step reaction paths to investigate their potential for the development of central nervous systems (CNS)-active and cholinesterase-targeted therapeutics in organophosphorus compound (OP) poisonings. Treating patients with acute OP poisoning is still a challenge despite the development of a large number of oxime compounds that should have the capacity to reactivate acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The activity of these two enzymes, crucial for neurotransmission, is blocked by OP, which has the consequence of disturbing normal cholinergic nerve signal transduction in the peripheral and CNS, leading to a cholinergic crisis. The oximes in use have one or two pyridinium rings and cross the brain-blood barrier poorly due to the quaternary nitrogen. Following our recent study on 2-thienostilbene oximes, in this paper, we described the synthesis of 63 heterostilbene derivatives, of which 26 oximes were tested as inhibitors and reactivators of AChE and BChE inhibited by OP nerve agents-sarin and cyclosarin. While the majority of oximes were potent inhibitors of both enzymes in the micromolar range, we identified several oximes as BChE or AChE selective inhibitors with the potential for drug development. Furthermore, the oximes were poor reactivators of AChE; four heterocyclic derivatives reactivated cyclosarin-inhibited BChE up to 70%, and cis,trans-5 [2-((Z)-2-(5-((E)-(hydroxyimino)methyl)thiophen-2-yl)vinyl)benzonitrile] had a reactivation efficacy comparable to the standard oxime HI-6. In silico analysis and molecular docking studies, including molecular dynamics simulation, connected kinetic data to the structural features of these oximes and confirmed their productive interactions with the active site of cyclosarin-inhibited BChE. Based on inhibition and reactivation and their ADMET properties regarding lipophilicity, CNS activity, and hepatotoxicity, these compounds could be considered for further development of CNS-active reactivators in OP poisoning as well as cholinesterase-targeted therapeutics in neurodegenerative diseases such as Alzheimer's and Parkinson's.

New insights into butyrylcholinesterase: Pharmaceutical applications, selective inhibitors and multitarget-directed ligands.

Butyrylcholinesterase (BChE), also known as pseudocholinesterase and serum cholinesterase, is an isoenzyme of acetylcholinesterase (AChE). It mediates the degradation of acetylcholine, especially under pathological conditions. Proverbial pharmacological applications of BChE, its mutants and modulators consist of combating Alzheimer's disease (AD), influencing multiple sclerosis (MS), addressing cocaine addiction, detoxifying organophosphorus poisoning and reflecting the progression or prognosis of some diseases. Of interest, recent reports have shed light on the relationship between BChE and lipid metabolism. It has also been proved that BChE is going to increase abnormally as a compensator for AChE in the middle and late stages of AD, and BChE inhibitors can alleviate cognitive disorders and positively influence some pathological features in AD model animals, foreboding favorable prospects and potential applications. Herein, the selective BChE inhibitors and BChE-related multitarget-directed ligands published in the last three years were briefly summarized, along with the currently known pharmacological applications of BChE, aiming to grasp the latest research directions. Thereinto, some emerging strategies for designing BChE inhibitors are intriguing, and the modulators based on target combination of histone deacetylase and BChE against AD is unprecedented. Furthermore, the involvement of BChE in the hydrolysis of ghrelin, the inhibition of low-density lipoprotein (LDL) uptake, and the down-regulation of LDL receptor (LDLR) expression suggests its potential to influence lipid metabolism disorders. This compelling prospect likely stimulates further exploration in this promising research direction.

Design, synthesis and biological evaluation of 1-aryldonepezil analogues as anti-Alzheimer's disease agents.

Aim: To design and synthesize a novel series of 1-aryldonepezil analogues. Materials & methods: The 1-aryldonepezil analogues were synthesized through palladium/PCy3-catalyzed Suzuki reaction and were evaluated for cholinesterase inhibitory activities and neuroprotective effects. In silico docking of the most effective compound was conducted. Results: The 4-tert-butylphenyl analogue exhibited good inhibitory potency against acetylcholinesterase and butyrylcholinesterase and had a favorable neuroprotective effect on H2O2-induced SH-SY5Y cell injury. Conclusion: The 4-tert-butylphenyl derivative is a promising lead compound for anti-Alzheimer's disease drug development.

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Biological and computational evaluation of novel benzofuranyl derivatives as acetylcholinesterase and butyrylcholinesterase inhibitors.

Aim: A highly efficient one-step method has been developed for the synthesis of benzofuranyl derivatives from 2-benzoylcyclohexane-1-carboxylic acid derivatives using chlorosulfonyl isocyanate. This novel method provides a practical, cost-effective and efficient approach. Materials & methods: The inhibitory effects of benzofuranyl derivatives on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes were investigated. Ki values were determined to range from 0.009 to 0.61 µM for AChE and 0.28 to 1.60 µM for BChE. Molecular docking analysis provided insights into the interaction modes and binding patterns of these compounds with AChE and BChE. Conclusion: Kinetic findings of our study suggest that some of our compounds exhibited more effective low micromolar inhibition compared with the reference, and these derivatives could be used to design more powerful agents.

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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 of new N-(5,6-methylenedioxybenzothiazole-2-yl)-2-[(substituted)thio/piperazine]acetamide/propanamide derivatives and evaluation of their AChE, BChE, and BACE-1 inhibitory activities.

In this study, the synthesis of N-(5,6-methylenedioxybenzothiazole-2-yl)-2-[(substituted)thio/piperazine]acetamide/propanamide derivatives (3a-3k) and to investigate their acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and ß-secretase 1 (BACE-1) inhibition activity were aimed. Mass, 1H NMR, and 13C NMR spectra were utilized to determine the structure of the synthesized compounds. Compounds 3b, 3c, 3f, and 3j showed AChE inhibitory activity which compound 3c (IC50 = 0.030 ± 0.001 µM) showed AChE inhibitory activity as high as the reference drug donepezil (IC50 = 0.0201 ± 0.0010 µM). Conversely, none of the compounds showed BChE activity. Compounds 3c and 3j showed the highest BACE-1 inhibitory activity and IC50 value was found as 0.119 ± 0.004 µM for compound 3j whereas IC50 value was 0.110 ± 0.005 µM for donepezil, which is one of the reference substance. Molecular docking studies have been carried out using the data retrieved from the server of the Protein Data Bank (PDBID: 4EY7 and 2ZJM). Using in silico approach behavior active compounds (3c and 3j) and their binding modes clarified.

Discovery of 4-benzylpiperazinequinoline BChE inhibitor that suppresses neuroinflammation for the treatment of Alzheimer's disease.

Butyrylcholinesterase (BChE) has attracted wide interest as a promising target in Alzheimer's disease (AD) investigation. BChE is considered to play a compensable role of hydrolyzing acetylcholine (ACh), and its positive correlation with ß-amyloid (Aß) deposition also promotes disease progression. Herein, we uncovered a selective potent BChE inhibitor S21-1011 (eqBChE IC50 = 0.059 ± 0.006 µM, hBChE IC50 = 0.162 ± 0.069 µM), which presented satisfactory druggability and therapeutic efficacy in AD models. In pharmacokinetics (PK) studies, S21-1011 showed excellent blood-brain barrier (BBB) permeability, metabolism stability and high oral-bioavailability. In pharmacodynamic (PD) studies, it protected neural cells from toxicity and inflammation stimulation in vitro. Besides, it also exerted anti-inflammatory effect and alleviated cognitive impairment in mice models induced by lipopolysaccharides (LPS) and Aß. Generally, this compound has been confirmed to function as a neuroprotector and cognition improver in various AD pathology-like models. Therefore, S21-1011, a novel potent BChE inhibitor, could be considered as a potential anti-AD candidate worthy of more profound investigation.

Advances in the Synthesis of Biologically Active Quaternary Ammonium Compounds.

This review provides a comprehensive overview of recent advancements in the design and synthesis of biologically active quaternary ammonium compounds (QACs). The covered scope extends beyond commonly reviewed antimicrobial derivatives to include synthetic agents with antifungal, anticancer, and antiviral properties. Additionally, this review highlights examples of quaternary ammonium compounds exhibiting activity against protozoa and herbicidal effects, as well as analgesic and anesthetic derivatives. The article also embraces the quaternary-ammonium-containing cholinesterase inhibitors and muscle relaxants. QACs, marked by their inherent permanent charge, also find widespread usage across diverse domains such as fabric softeners, hair conditioners, detergents, and disinfectants. The effectiveness of QACs hinges greatly on finding the right equilibrium between hydrophilicity and lipophilicity. The ideal length of the alkyl chain varies according to the unique structure of each QAC and its biological settings. It is expected that this review will provide comprehensive data for medicinal and industrial chemists to design and develop novel QAC-based products.

Lead optimization based design, synthesis, and pharmacological evaluation of quinazoline derivatives as multi-targeting agents for Alzheimer's disease treatment.

The complexity and multifaceted nature of Alzheimer's disease (AD) have driven us to further explore quinazoline scaffolds as multi-targeting agents for AD treatment. The lead optimization strategy was utilized in designing of new series of derivatives (AK-1 to AK-14) followed by synthesis, characterization, and pharmacological evaluation against human cholinesterase's (hChE) and ß-secretase (hBACE-1) enzymes. Amongst them, compounds AK-1, AK-2, and AK-3 showed good and significant inhibitory activity against both hAChE and hBACE-1 enzymes with favorable permeation across the blood-brain barrier. The most active compound AK-2 revealed significant propidium iodide (PI) displacement from the AChE-PAS region and was non-neurotoxic against SH-SY5Y cell lines. The lead molecule (AK-2) also showed Aß aggregation inhibition in a self- and AChE-induced Aß aggregation, Thioflavin-T assay. Further, compound AK-2 significantly ameliorated Aß-induced cognitive deficits in the Aß-induced Morris water maze rat model and demonstrated a significant rescue in eye phenotype in the Aꞵ-phenotypic drosophila model of AD. Ex-vivo immunohistochemistry (IHC) analysis on hippocampal rat brains showed reduced Aß and BACE-1 protein levels. Compound AK-2 suggested good oral absorption via pharmacokinetic studies and displayed a good and stable ligand-protein interaction in in-silico molecular modeling analysis. Thus, the compound AK-2 can be regarded as a lead molecule and should be investigated further for the treatment of AD.

Two Fluorescent Probes for Recognition of Acetylcholinesterase: Design, Synthesis, and Comparative Evaluation.

In this study, two "on-off" probes (BF2-cur-Ben and BF2-cur-But) recognizing acetylcholinesterase (AChE) were designed and synthesized. The obtained probes can achieve recognition of AChE with good selectivity and pH-independence with a linear range of 0.5~7 U/mL and 0.5~25 U/mL respectively. BF2-cur-Ben has a lower limit of detection (LOD) (0.031 U/mL), higher enzyme affinity (Km = 16 ± 1.6 µM), and higher inhibitor sensitivity. A responsive mechanism of the probes for AChE was proposed based on HPLC and mass spectra (MS) experiments, as well as calculations. In molecular simulation, BF2-cur-Ben forms more hydrogen bonds (seven, while BF2-cur-But has only four) and thus has a more stable enzyme affinity, which is mirrored by the results of the comparison of Km values. These two probes could enable recognition of intracellular AChE and probe BF2-cur-Ben has superior cell membrane penetration due to its higher log p value. These probes can monitor the overexpression of AChE during apoptosis of lung cancer cells. The ability of BF2-cur-Ben to monitor AChE in vivo was confirmed by a zebrafish experiment.

Exploring fluorine-substituted piperidines as potential therapeutics for diabetes mellitus and Alzheimer's diseases.

In the current study, a series of fluorine-substituted piperidine derivatives (1-8) has been synthesized and characterized by various spectroscopic techniques. In vitro and in vivo enzyme inhibitory studies were conducted to elucidate the efficacy of these compounds, shedding light on their potential therapeutic applications. To the best of our knowledge, for the first time, these heterocyclic structures have been investigated against α-glucosidase and cholinesterase enzymes. The antioxidant activity of the synthesized compounds was also assessed. Evaluation of synthesized compounds revealed notable inhibitory effects on α-glucosidase and cholinesterases. Remarkably, the target compounds (1-8) exhibited extraordinary α-glucosidase inhibitory activity as compared to the standard acarbose by several-fold. Subsequently, the potential antidiabetic effects of compounds 2, 4, 5, and 6 were validated using a STZ-induced diabetic rat model. Kinetic studies were also performed to understand the mechanism of inhibition, while structure-activity relationship analyses provided valuable insights into the structural features governing enzyme inhibition. Kinetic investigations revealed that compound 4 displayed a competitive mode of inhibition against α-glucosidase, whereas compound 2 demonstrated mixed-type behavior against AChE. To delve deeper into the binding interactions between the synthesized compounds and their respective enzyme targets, molecular docking studies were conducted. Overall, our findings highlight the promising potential of these densely substituted piperidines as multifunctional agents for the treatment of diseases associated with dysregulated glucose metabolism and cholinergic dysfunction.

Structure-based design of multitargeting ChEs-MAO B inhibitors based on phenyl ring bioisosteres: AChE/BChE selectivity switch and drug-like characterization.

A structure-based drug design approach was focused on incorporating phenyl ring heterocyclic bioisosteres into coumarin derivative 1, previously reported as potent dual AChE-MAO B inhibitor, with the aim of improving drug-like features. Structure-activity relationships highlighted that bioisosteric rings were tolerated by hMAO B enzymatic cleft more than hAChE. Interestingly, linker homologation at the basic nitrogen enabled selectivity to switch from hAChE to hBChE. In the present work, we identified thiophene-based isosteres 7 and 15 as dual AChE-MAO B (IC50 = 261 and 15 nM, respectively) and BChE-MAO B (IC50 = 375 and 20 nM, respectively) inhibitors, respectively. Both 7 and 15 were moderately water-soluble and membrane-permeant agents by passive diffusion (PAMPA-HDM). Moreover, they were able to counteract oxidative damage induced by both H2O2 and 6-OHDA in SH-SY5Y cells and predicted to penetrate into CNS in a cell-based model mimicking blood-brain barrier. Molecular dynamics (MD) simulations shed light on key differences in AChE and BChE recognition processes promoted by the basic chain homologation from 7 to 15.

Discovery of Novel Cholinesterase Inhibitors Easily Crossing the Blood-Brain Barrier via Structure-Property Relationship Investigation: Methylenedioxy-Cinnamicamide Containing Tertiary Amine Side Chain.

In the present investigation, a series of dimethoxy or methylenedioxy substituted-cinnamamide derivatives containing tertiary amine moiety (N. N-Dimethyl, N, N-diethyl, Pyrrolidine, Piperidine, Morpholine) were synthesized and evaluated for cholinesterase inhibition and blood-brain barrier (BBB) permeability. Although their chemical structures are similar, their biological activities exhibit diversity. The results showed that all compounds except for those containing morpholine group exhibited moderate to potent acetylcholinesterase inhibition. Preliminary screening of BBB permeability shows that methylenedioxy substituted compounds have better brain permeability than the others. Compound 10c, containing methylenedioxy and pyrrolidine side chain, showed a better acetylcholinesterase inhibition (IC50: 1.52±0.19 µmol/L) and good blood-brain barrier permeability. Further pharmacokinetic investigation of compound 10c using ultra high performance liquid chromatography-mass/mass spectrometry (UPLC-MS/MS) in mice showed that compound 10c in brain tissue reached its peak concentration (857.72±93.56 ng/g) after dosing 30 min. Its half-life in the serum is 331 min (5.52 h), and the CBrain/CSerum at various sampling points is ranged from 1.65 to 4.71(Mean: 2.76) within 24 hours. This investigation provides valuable information on the chemistry and pharmacological diversity of cinnamic acid derivatives and may be beneficial for the discovery of central nervous system drugs.

In Vitro and In Vivo Investigations of Chromone Derivatives as Potential Multitarget-Directed Ligands: Cognitive Amelioration Utilizing a Scopolamine-Induced Zebrafish Model.

Alzheimer's disease is a complex neurological disorder linked with multiple pathological hallmarks. The interrelation of therapeutic targets assists in the enhancement of cognitive decline through interference with overall neuronal transmission. We have synthesized and screened various chromone derivatives as potential multitarget-directed ligands for the effective treatment of Alzheimer's disease. The synthesized compounds exhibited multipotent activity against AChE, BuChE, MAO-B, and amyloid ß aggregation. Three potent compounds, i.e., VN-3, VN-14, and VN-19 were identified that displayed remarkable activities against different targets. These compounds displayed IC50 values of 80 nM, 2.52 µM, and 140 nM against the AChE enzyme, respectively, and IC50 values of 2.07 µM, 70 nM, and 450 nM against the MAO-B isoform, respectively. VN-3 displayed potent activity against self-induced Aß1-42 aggregation with inhibition of 58.3%. In the ROS inhibition studies, the most potent compounds reduced the intracellular ROS levels up to 80% in SH-SY5Y cells at 25 µM concentration. The compounds were found to be neuroprotective and noncytotoxic even at a concentration of 25 µM against SH-SY5Y cells. In silico studies showed that the compounds were nicely accommodated in the active sites of the receptors along with thermodynamically stable orientations. Compound VN-19 exhibited a balanced multitargeting profile against AChE, BuChE, MAO-B, and Aß1-42 enzymes and was further evaluated for in vivo activities on the scopolamine-induced zebrafish model. VN-19 was found to ameliorate the cognitive decline in zebrafish brains by protecting them against scopolamine-induced neurodegeneration. Thus, VN-3, VN-14, and VN-19 were identified as potent multitarget-directed ligands with a balanced activity profile against different targets and can be developed as therapeutics for AD.

Design, Synthesis, and Biological Evaluation of Novel Tetrahydroacridin Hybrids with Sulfur-Inserted Linkers as Potential Multitarget Agents for Alzheimer's Disease.

Alzheimer's disease (AD) is a complex neurodegenerative disease that can lead to the loss of cognitive function. The progression of AD is regulated by multiple signaling pathways and their associated targets. Therefore, multitarget strategies theoretically have greater potential for treating AD. In this work, a series of new hybrids were designed and synthesized by the hybridization of tacrine (4, AChE: IC50 = 0.223 µM) with pyrimidone compound 5 (GSK-3ß: IC50 = 3 µM) using the cysteamine or cystamine group as the connector. The biological evaluation results demonstrated that most of the compounds exhibited moderate to good inhibitory activities against acetylcholinesterase (AChE) and glycogen synthase kinase 3ß (GSK-3ß). The optimal compound 18a possessed potent dual AChE/GSK-3ß inhibition (AChE: IC50 = 0.047 ± 0.002 µM, GSK-3ß: IC50 = 0.930 ± 0.080 µM). Further molecular docking and enzymatic kinetic studies revealed that this compound could occupy both the catalytic anionic site and the peripheral anionic site of AChE. The results also showed a lack of toxicity to SH-SY5Y neuroblastoma cells at concentrations of up to 25 µM. Collectively, this work explored the structure-activity relationships of novel tetrahydroacridin hybrids with sulfur-inserted linkers, providing a reference for the further research and development of new multitarget anti-AD drugs.

Diosmetin derivatives as multifunctional anti-AD ligands: Design, synthesis, and biological evaluation.

With the increasing aging population, rational design of drugs for Alzheimer's disease (AD) treatment has become an important research area. Based on the multifunctional design strategy, four diosmetin derivatives (1-4) were designed, synthesized, and characterized by 1H NMR, 13C NMR, and MS. Docking study was firstly applied to substantiate the design strategies and then the biological activities including cholinesterase inhibition, metal chelation, antioxidation and ß-amyloid (Aß) aggregation inhibition in vitro were evaluated. The results showed that 1-4 had good acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibition, metal chelation (selective chelation of Cu2+ ions), antioxidation, self-induced, Cu2+-induced, and AChE-induced Aß aggregation inhibition activities, and suitable blood-brain barrier (BBB) permeability. Especially, compound 3 had the strongest inhibitory effect on AChE (10-8 M magnitude) and BuChE (10-7 M magnitude) and showed the best inhibition on AChE-induced Aß aggregation with 66.14% inhibition ratio. Furthermore, compound 3 could also reduce intracellular reactive oxygen species (ROS) levels in Caenorhabditis elegans and had lower cytotoxicity. In summary, 3 might be considered as a potential multifunctional anti-AD ligand.

Coumarin-azasugar-benzyl conjugates as non-neurotoxic dual inhibitors of butyrylcholinesterase and cancer cell growth.

We have applied the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to prepare a library of ten coumarin-azasugar-benzyl conjugates and two phthalimide-azasugar-benzyl conjugates with potential anti-Alzheimer and anti-cancer properties. The compounds were evaluated as cholinesterase inhibitors, demonstrating a general preference, of up to 676-fold, for the inhibition of butyrylcholinesterase (BuChE) over acetylcholinesterase (AChE). Nine of the compounds behaved as stronger BuChE inhibitors than galantamine, one of the few drugs in clinical use against Alzheimer's disease. The most potent BuChE inhibitor (IC50 = 74 nM) was found to exhibit dual activities, as it also showed high activity (GI50 = 5.6 ± 1.1 µM) for inhibiting the growth of WiDr (colon cancer cells). In vitro studies on this dual-activity compound on Cerebellar Granule Neurons (CGNs) demonstrated that it displays no neurotoxicity.