Potent Acetylcholinesterase Inhibitors Research Articles

Elevated Fibrinogen Level Reduces Therapeutic Efficiency of AD Drugs: Biophysical Insights into the Interaction of FDA-Approved Cholinesterase Inhibitors with Human Fibrinogen.

Despite being the second most abundant protein in blood plasma, reports on the interaction of drugs with fibrinogen (FIB) are relatively scarce. The effect of FIB on the therapeutic potency of four FDA-approved Alzheimer's disease drugs, namely, tacrine (TAC), donepezil (DON), eserine (ESE), and huperzine (HUP), was investigated through a combination of different in vitro and in silico experiments. The efficiency of the drugs in inhibiting the activity of acetylcholinesterase (AChE) was significantly reduced in the presence of FIB. This effect was even found to be more substantial than that for the most abundant plasma protein, human serum albumin (HSA). For example, the relative change in IC50 for TAC was found to be 65% in 10 μM FIB as opposed to 43% in the presence of 250 μM HSA. The relative trend of modulation in AChE activity showed consistency with the binding efficiency of the drugs and FIB. The sequestration of drugs in FIB, therefore reducing the availability of free drugs in solution, was identified to be the primary cause for the decrease in the AChE inhibition potency. This study aims to establish FIB as a vital component, while considering the therapeutic effectiveness of different newly developed AChE inhibitors.

In Vitro and In Silico Kinetic Studies of Patented 1,7-diEthyl and 1,7-diMethyl Aminoalkanol Derivatives as New Inhibitors of Acetylcholinesterase.

Two aminoalkanol derivatives of 1,7-diEthyl-8,9-diphenyl-4azatricyclo (5.2.1.02.6) dec-8-ene-3,5,10-trione and two derivatives of 1,7-diMethyl-8,9-diphenyl-4-azatricyclo (5.2.1.02.6) dec-8-ene-3,5,10-trione were evaluated in vitro for their inhibition efficacy of acetylcholinesterase. The Km, Vmax, slope angles of Lineweaver–Burk plots, Ki and IC50 values showed that all four aminoalkanol derivatives are competitive inhibitors of acetylcholinesterase whose inhibitory potency depends, to a varying extent, on the nature of the four different substituents present in the main compound structure. Studies have shown that the most potent acetylcholinesterase inhibitors are derivatives containing isopropylamine and/or methyl substituents in their structure. In contrast, dimethylamine and/or ethyl substituents seem to have a weaker, albeit visible, effect on the inhibitory potency of acetylcholinesterase. Additionally, docking studies suggest that studied compounds binds with the peripheral anionic site and not enter into the catalytic pocket due to the presence of the sterically extended substituent.

Biological activity studies on Klasea serratuloides (DC) Greuter & Wagenitz subsp. karamanica B. Dogan & A. Duran extracts obtained with different extraction methods

The aim of this study was to investigate the antioxidant and enzyme inhibition activities of methanol extracts prepared from Klasea serratuloides (DC) Greuter & Wagenitz subsp. karamanica B. Dogan & A. Duran with Soxhlet, ultrasonic extraction, and maceration methods. 1,1-Diphenyl-2-picryl hydroxyl (DPPH) quenching assay and 2,2’-azinobis-3- ethylbenzothiozoline-6-sulfonic acid (ABTS) cation decolorization test were used to evaluate in vitro radical scavenging activity. The total phenolic content was determined with the Folin-Ciocalteu method while the total flavonoid content was evaluated by the aluminum chloride colorimetric method. According to the results, DPPH, ABTS radical scavenging activity and iron chelating activity of methanol of Klasea serratuloides were shown concentration-dependent manner. The extract obtained from maceration was found to be higher than the other extracts. It suggests that the maceration technique was more effective than the other extraction methods for the determination of the phenolic content. The methanol extract of KS using soxhlet (61.17 ± 3.62) and ultrasonic extraction (58.76 ± 1.46) showed higher inhibition than the extract prepared with maceration methods (34.54 ± 0.73) against BChE. All extracts displayed moderate inhibition activity against AChE. As for enzyme inhibition activity, the extract from soxhlet method was found to be more potent tyrosinase, acetylcholinesterase and butyrylcholinesterase inhibitors than the other extracts prepared by ultrasound assisted extraction and maceration methods. The present study suggests that K. serratuloides should be given special attention to conduct further investigation for its phytochemical constituents that attribute to their antioxidant potentials, and enzyme inhibition activities.

In silico and in vitro Approach To Identify Memory Enhancers from Sida rhombifolia L.

<p style="text-align: justify;"><strong>Background: </strong><em>Sida rhombifolia </em>L. is a well documented Ayurvedic medicine for the management of neurodegenerative diseases and to enhance cognitive function. Researchers demonstrated its activities under various animal model/s, but lack the probable molecular mechanism in the treatment of Alzheimer&rsquo;s disease. Current study was aimed to identify the acetylcholinesterase (AChE) inhibitory potency of phytocompounds and enriched fractions from <em>S.rhombifolia </em>using <em>in vitro</em> and network pharmacology approaches.<em> </em><strong>Methods:</strong> Phytocompounds were retrieved from phytochemical databases, scientific reports and quired for druggability. Protein targets were predicted using BindingDB (<em>p</em>&ge;0.7). STRING database and KEGG pathway were utilized to perform gene set enrichment analysis and to identify the probable pathways modulated by the phytocompounds. Cytoscape v3.6.1 was used to construct a target-compound-pathway network. Docking was performed by PyRx 0.8v. Enriched fractions of <em>S. rhombifolia</em> were tested for <em>in vitro </em>AChE inhibitory potency using the AChE enzyme.<strong> Results: </strong>Among 35 compounds, 26 compounds showed positive drug likeness property. Out of 26 compounds, 9 compounds i.e. 2D-hydroxyecdysone, ecdysone, pterosterone-3-O-&beta;-D-glucopyranoside, acacetin, kaempferol, sanguinine, vascicine, vasicinol, vasicinone were predicted to target AChE and other 9 therapeutic targets involved in Alzheimer&rsquo;s disease (AD). Acacetin scored lowest binding energy with AChE (-8.9kcal/mol). Among the selected enriched fractions, hexane fraction pertains highest AChE inhibition (IC₅₀ 12.87&mu;g/ml) compared to clinical approved drug Donepezil (IC₅₀2.92&mu;g/ml).<strong> Conclusion: </strong>The role of <em>S.rhombifolia</em> for the management of AD could be attributed due to the major effect of 2D-hydroxyecdysone, ecdysone, pterosterone-3-O-&beta;-Dglucopyranoside, acacetin, kaempferol, sanguinine, vascicine, vasicinol, vasicinone on AChEand their action on multiple protein molecules associated with AD pathogenesis. <strong>Key words:</strong> Alzheimer&rsquo;s disease, Acacetin, Acetylcholinesterase, In silico docking, Network pharmacology, Sida rhombifolia, Sangunine.

Design and synthesis of novel chalcone derivatives and evaluation of their inhibitory activities against acetylcholinesterase.

According to the cholinergic hypothesis, an increase in the acetylcholine level in Alzheimer's disease patients relatively slows down the symptoms of the disease. The most commonly used drug, donepezil, is a cholinesterase inhibitor. In this study, 12 new chalcones (2a-l) were designed and synthesized. In biological activity studies, the acetylcholinesterase (AChE) and butyrylcholinesterase inhibitory potentials of all compounds were evaluated using the in vitro Ellman method. The biological evaluation showed that compounds 2d, 2f, 2j, and 2l displayed significant activity against AChE. The compounds 2d, 2f, 2j, and 2l displayed IC50 values of 0.042, 0.024, 0.053, and 0.033 µM against AChE, respectively. The reference drug donepezil (IC50 = 0.021 µM) also displayed significant inhibition of AChE. The inhibitory activities of these compounds for β-amyloid plaque aggregation were investigated. The enzyme kinetic study was performed to observe the effect of the most active compound 2f on the substrate-enzyme relationship, and a mixed-type inhibition of AchE was determined. Further, docking simulation also revealed that these compounds (2d, 2f, 2j, and 2l) interacted with the enzyme active site in a similar manner to donepezil. The most active derivative, compound 2f, interacted with the amino acids Trp286, Phe295, Tyr341, Trp86, and Glu202.

Alkaloid Profiling and Cholinesterase Inhibitory Potential of Crinum × amabile Donn. (Amaryllidaceae) Collected in Ecuador.

Natural products are one of the main sources for developing new drugs. The alkaloids obtained from the plant family Amaryllidaceae have interesting structures and biological activities, such as acetylcholinesterase inhibition potential, which is one of the mechanisms used for the palliative treatment of Alzheimer’s disease symptoms. Herein we report the alkaloidal profile of bulbs and leaves extracts of Crinum × amabile collected in Ecuador and their in vitro inhibitory activity on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. Using Gas Chromatography coupled to Mass Spectrometry (GC-MS), we identified 12 Amaryllidaceae alkaloids out of 19 compounds detected in this species. The extracts from bulbs and leaves showed great inhibitory activity against AChE and BuChE, highlighting the potential of Amaryllidaceae family in the search of bioactive molecules.

Identifying amine fragments as potential inhibitors of acetylcholinesterase and butyrylcholinesterase through in silico analysis and validation through in vitro enzyme inhibition analysis

AbstractBackgroundThe cholinesterases [ChEs; acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)] which are involved in cholinergic neurotransmission are target for drug development against cognitive dysfunction in Alzheimer’s disease. The search for novel ChEs inhibitors with improved biological profiles continues to be of great interest. Currently know inhibitors of ChEs such as galatamine, tacrine, donepezil and rivastigmine are amine‐based compound. Keeping this view, in the present study virtual screening was carried out to identify the potential amine fragment that interacted with the ChEs in in silico. The selected molecules were analyzed by molecular docking and molecular dynamics simulation. The best interacted molecule in in silico was further characterized for its inhibition against AChE and BChE in in vitro.MethodHigh Throughput Virtual Screening (HTVS) of various amine fragments was carried out in Schrödinger suite. Identified top ten molecules were subjected to molecular docking analysis using Induced Fit Docking (IFD) module. Molecular dynamics (MD) simulation of top three scored compounds were carried out to understand the stability of the interaction with ChEs. In silico quantum crystallography studies was done to understand the involvement of functional group in the interaction with ChEs. In vitro inhibition and kinetic analysis of these compounds against ChEs was performed to determine the inhibitory constant and type of inhibition.ResultAmong the amine compounds screened, three compounds 2‐aminoquinoline (2AQ), 2‐aminobenzimidazole (2AB) and 2‐amino‐1‐methylbenzimidazole (2AMB) was identified to interact with ChEs with lowest docking score. Further MD simulation confirmed the stable binding of these compounds in the active site of the ChEs. Topological and electrostatic properties of intermolecular interactions between these compounds with ChEs showed that amine group played important role in interacting with protein structure. These amine compounds inhibited the BChE and different molecular forms of AChE at micromolar concentration. Kinetic analysis revealed the mixed‐type of inhibition.ConclusionAmine fragments screened for interaction with ChEs in in silico. Three compounds (2AQ, 2AB and 2AMB) showed better interaction in molecular docking and molecular dynamics analysis. These compounds showed inhibition against ChEs in in vitro.

In vitro and in silico investigation of cholinesterase inhibition and anti‐radical properties of Solanum macrocarpon leaf extracts: A preliminary anti‐Alzheimer's study

AbstractBackgroundAlzheimer's disease (AD) is an age‐associated, progressive neurodegenerative disease characterized by decline in cognitive function. There is presently no cure for AD and the currently used drugs have limited efficacy. Cholinergic enzyme inhibition, oxidative stress and neuroinflammation have been growing areas of research in the pharmacological management of AD (Simunkova et al., 2019). Furthermore, computational approaches have been instrumental in designing and discovering new drugs for several diseases (Romano &amp; Tatonetti, 2018). Solanum macrocarpon L. (eggplant) is a specie of African ancestry reported to be an ethno‐ medicinal plant that improves memory (Ogunsuyi et al., 2018). This study therefore investigated the antioxidant and acetylcholinesterase (AChE) inhibitory potential of S. macrocarpon leaf extracts, identified active compound(s) and explored their enzyme‐ligand interactions using In silico approaches to discover new functional leads for AD.MethodMethanol extract and fractions of S. macrocarpon leaves were subjected to phytochemical investigation of AChE inhibitory activity and cell‐free antioxidant activity. Phytochemicals were identified through the profiling of the most potent fraction using Liquid Chromatography‐Mass Spectrometry (LC‐MS) and Gas Chromatography‐Mass Spectrometry (GC‐MS). Molecular docking was performed employing AutoDock Vina. The prediction of the ADMET properties was obtained using pkCSM and SwissADME online tools. Furthermore, the compound(s) with favorable pharmacokinetic properties and interaction with key residues within the AChE active site was selected for molecular dynamics (MD) simulation studies using GROMACS 5.0.7.ResultThe S. macrocarpon leaves ethyl‐acetate fraction (SMEA) displayed the highest concentration‐dependent inhibition of AChE and highest antioxidant capacity among the fractions. Seventy‐eight (78) and sixty (60) compounds were tentatively identified from the LC‐MS and GC‐MS of SMEA respectively. A total number of 21 compounds demonstrated better docking score than the standard, eserine and interacted with key residues within the human acetylcholinesterase (PDB ID:4EY7) active site akin to Donepezil. Amongst the compounds with the least docking score, 1,1‐Biphenyl‐4‐carboxylic acid showed the most favorable pharmacokinetic properties. Also, the 10ns MD produced a trajectory which showed stable Root‐Mean‐Square‐Deviation and favorable g_mmpbsa energy calculations.ConclusionThe current study proposes that 1,1‐Biphenyl‐4‐carboxylic acid, a constituent of S. macrocarpon is a potential lead compound for AD management.

The impact of ABCB1 gene polymorphism (C3435T) and its expression on response to Donepezil in Moroccan patients with Alzheimer's disease

Donepezil is a specific and potent acetylcholinesterase inhibitor; it can improve the cognitive and executive functions of patients with mild to moderately severe Alzheimer's disease (AD). P-glycoproteins (P-gp) are encoded by the ATP-binding cassette B1 (ABCB1) gene. Polymorphisms in ABCB1 gene could affect the response to donepezil. The present study aims to investigate the association between ABCB1 C3435T polymorphism and AD risk in Moroccan patients and to evaluate the ABCB1 gene expression in AD cases and its effect on clinicopathological parameters and response to donepezil treatment. A total of 54 Moroccan patients and 63 healthy controls were genotyped by PCR-RFLP method. Moreover, mRNA was quantified using the RT-qPCR approach. The results revealed that CT genotype and T allele were statistically more frequent in healthy controls than in AD patients (P = 0.015 and P = 0.04 respectively). Moderate AD, illiterate patients and some symptoms were significantly higher in drug resistant patients. In addition, ABCB1 gene expression was associated with diabetes (OR = 0.10; 95% CI = [0.01–0.53]; P = 0.015) and age (OR = 5.19, 95% CI = [1.07–32.9]; P = 0.054). However, no effect of the clinical parameters and symptoms has been observed on the resistance to Donepezil. This result could be used to predict the prognosis of patients before drug administration. However, further studies are needed to confirm or not these findings.

Synthesis and molecular dynamic simulation studies of novel N-(1-benzylpiperidin-4-yl) quinoline-4-carboxamides as potential acetylcholinesterase inhibitors

Novel quinoline-4-carboxamide derivatives was synthesized as acetylcholinesterase inhibitors. In the amidation reaction in addition of target compounds a bis-N-acylurea were also obtained. 5f with the lowest docking energy, exhibited the most anticholinesterase inhibitory potency. A new series of N-(1-benzylpiperidin-4-yl) quinoline-4-carboxamide derivatives was designed and synthesized as potential acetylcholinesterase inhibitors. The compounds were characterized by nuclear magnetic resonance, infrared and mass spectrometry. In the amidation reaction in addition of target compounds 5a -5 h, a bis-N-acylurea were also obtained especially when we added more carbonyldiimidazole (CDI) for the completion of the reaction. Although docking study of these compounds predicted that they will inhibit acetylcholinesterase (AChE) protein strongly and more than the reference drugs, the in vitro evaluation of the quinolines 5a -5 h revealed that most of them had moderate activity toward AChE. The results showed that there is a correlation between anticholinesterase inhibitory potency and docking energy of compounds. Among these compounds, 5f with the lowest docking energy, exhibited the most anticholinesterase inhibitory potency. Molecular dynamics simulation and molecular docking studies of compound 5f into the binding site of acetylcholinesterase exhibited the probable interactions of 5f with the binding site of acetylcholinesterase.

Diversity of Endophytic Fungi in Huperzia serrata and Their Acetylcholinesterase Inhibitory Activity

Huperzia serrata is a Huperzine A (HupA)-producing herb. HupA is a potent, reversible, highly specific, centrally active and selective acetylcholinesterase inhibitor, and is commonly used to improve Alzheimer’s disease.At present, H. serrata resources have been overexploited and their artificial cultivation has lagged behind the need, so the market demand cannot be met. In this study, the diversity of the endophytic fungi in H. serrata was studied by high-throughput sequencing and traditional culture methods. Furthermore, the ability of the isolated endophytic fungi to produce acetylcholinesterase-inhibiting activity was evaluated. The results related to the diversity of fungi between high-throughput sequencing and traditional culture methods were compared. With high-throughput sequencing, five phyla, 22 classes, 55 orders, 120 families, and 178 genera of fungi were detected in Hubei Province, and five phyla, 22 classes, 54 orders, 124 families, and 196 genera were detected in Fujian Province. After cultivation with traditional culture methods, two phyla, three classes, five orders, six families, and six genera were detected in Hubei, and one phylum, three classes, five orders, five families, and six genera in Fujian. The endophytic fungi of H. serrata are highly diverse, and the results of high-throughput sequencing comprehensively reflect their community compositions. When the acetylcholinesterase-inhibiting activity of the isolated and cultured endophytic fungi was determined, five and three endophytic fungi from Hubei and Fujian Provinces, respectively, had good inhibitory activity (inhibition rate &gt; 50%). Most of them were separated from leaf tissue. The strain HBR-1 and strain FJL-5 had the strongest inhibitory effects on AChE, with inhibition rates of 72.34% and 60.54%, respectively. Although only a proportion of the endophytic fungi was isolated with traditional culture methods, metabolites with broad potential applications can be isolated from these fungal cultures. The combination of high-throughput sequencing and traditional culture methods can be used to isolate and purify endophytic fungi in a targeted manner, gain many endophytic fungi, and enrich the endophytic fungi resource library.

Biological evaluation and molecular docking studies of 4-aminobenzohydrazide derivatives as cholinesterase inhibitors

• Synthesis of mono and disubstituted 4-amino benzohydrazides. • Evaluating the 4-amino benzohydrazide derivative compounds as a potential acetylcholinesterase and butyrylcholinesterase inhibitors. • Molecular docking analyze of 4-amino benzohydrazide derivative compounds in active site of acetylcholinesterase and butyrylcholinesterase. Nowadays, inhibition of the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes have emerged as an encouraging approach in the treatment of dementia and remission of symptoms of Alzheimer's disease. Therefore, inhibition of cholinesterases is one of the main targets by researchers. Benzohydrazides are biologically active compounds and have various pharmacological effects, bearing these in mind, we investigated the inhibitory effects of some mono or di-substituted 4-aminobenzohydrazide derivatives (1a-11a) against AChE and BChE. For this purpose, we studied the inhibition effects (IC 50 , K i values, and inhibition types) of these molecules on AChE and BChE enzymes. Based on the results, compound 3a showed potent AChE and BChE inhibition (IC 50 = 0.59 and 0.15 μM). The K i values of the compounds ( 3a, 4a, and 8a ) showing the best inhibition effect against AChE and BChE were calculated and these values ranged from 0.10 ± 0.04 to 5.10 ± 2.14 μM. To determine the possible binding mechanisms with the active sites of both enzymes of compounds 3a, 4a , and 8a having strong inhibitory effects, docking analyses were performed. According to the docking results, compound 3a showed the best binding affinity (-7.3 kcal/mol for AChE and -6.8 kcal/mol for BChE) against both enzymes.

Concentration-dependent effects of chlorpyrifos oxon on peroxisome proliferator-activated receptor signaling in MCF-7 cells

Chlorpyrifos oxon (CPO) is the active metabolite of the organophosphorus pesticide, chlorpyrifos. CPO is a potent inhibitor of acetylcholinesterase (AChE) and other serine hydrolases including fatty acid amide hydrolase (FAAH). AChE is critical in regulating cholinergic signaling while FAAH catalyzes the inactivation of fatty acid signaling lipids including the endocannabinoid (eCB) N-arachidonylethanolamine (anandamide, AEA) and eCB-like metabolites (e.g., oleoylethanolamide, OEA). AEA and OEA are both peroxisome proliferator-activated receptor (PPAR) agonists that regulate numerous genes involved in lipid metabolism and energy homeostasis. We used the MCF-7 human breast cancer cell line, which expresses AChE, FAAH and PPAR alpha and gamma subtypes, to evaluate the potential effects of CPO on PPAR-related gene expression in an in vitro human cell system. CPO elicited relatively similar concentration-dependent inhibition of both AChE and FAAH. Marked concentration- and time-dependent changes in the expression of four selected PPAR-related genes, LXRα, ACOX1, ABCG2 and AGPAT2, were noted. These findings suggest chlorpyrifos may influence lipid metabolism through blocking the degradation of eCBs or eCB-like metabolites and in turn affecting PPAR receptor activation. The results highlight the potential for non-cholinesterase actions of this common insecticide metabolite through disruption of PPAR signaling including effects on lipid metabolism, immune function and inflammation.

Fractionation of Lycopodiaceae Alkaloids and Evaluation of Their Anticholinesterase and Cytotoxic Activities.

In view of the abundant evidence that Lycopodiaceae alkaloids, including the well-known huperzine A (HupA), are among the potent acetylcholinesterase (AChE) inhibitors, an attempt was made to search for new compounds responsible for this property. For this purpose, three plant species belonging to the Lycopodiaceae family, commonly found in the Euro-Asia region, were subjected to the isolation of bioactive compounds, their identification and subsequent evaluation of their anticholinesterase and cytotoxic activities. Methanolic extracts of two Lycopodium and one Hupezia species were obtained via optimized pressurized liquid extraction (PLE) and then pre-purified using innovative gradient vacuum liquid chromatography (gVLC). For the first time, three sorbents of different porosity packed in polypropylene cartridges and mobile phase systems of different polarity were used to elute the target compounds. This technique proved to be a rapid tool for the obtainment of alkaloid fractions and allowed one to select the appropriate process conditions to yield potent AChE inhibitors in each of the species studied. More than 100 collected fractions were analyzed via HPLC/ESI-QTOF-MS, which enabled one to detect more than 50 compounds, including several new ones previously unreported. Some of them were present in high purity fractions (60–90% of the established purity). TLC bioautography assays proved that the analyzed species are rich sources of AChE inhibitors, but H. selago showed the highest anti-AChE activity. Additionally, the modified silanized silica gel sorbent used allowed one to isolate L. clavatum alkaloids more efficiently using an aqueous reversed-phase solvent system. Furthermore, the tested extracts from the three plant extracts were found to be safe, as they did not exhibit cytotoxicity to skin fibroblasts.

Cytotoxic activity and influence on acetylcholinesterase of series dinuclear platinum(II) complexes with aromatic nitrogen-containing heterocyclic bridging ligands: Insights in the mechanisms of action

Herein, the stability, lipophilicity, in vitro cytotoxicity, and influence on acetylcholinesterase of five dinuclear platinum(II) complexes with the general formula [{Pt(en)Cl}2(μ-L)]2+ (L is a different aromatic nitrogen-containing heterocyclic bridging ligands pyrazine (pz, Pt1), pyridazine (pydz, Pt2), quinoxaline (qx, Pt3), phthalazine (phtz, Pt4) and quinazoline (qz, Pt5), while en is bidentate coordinated ethylenediamine) were evaluated. The most active analyzed platinum complexes induced time-dependent growth inhibition of A375, HeLa, PANC-1, and MRC-5 cells. The best efficiency was achieved on HeLa and PANC-1 cells for Pt1, Pt2, and Pt3 at the highest concentration, while Pt1 was significantly more potent than cisplatin at a lower concentration. Additionally, a lower effect on normal cells was observed compared to cisplatin, which may indicate potentially fewer side effects of these complexes. Selected complexes induce reactive oxygen species and apoptosis on tumor cell lines. The most potent reversible acetylcholinesterase (AChE) inhibitors were Pt2, Pt4, and Pt5. Pt1 showed similar inhibitory potential toward AChE as cisplatin, but a different type of inhibition, which could contribute to lower neurotoxicity. Docking studies revealed that Pt2 and Pt4 were bound to the active gorge above the catalytic triad. In contrast, the other complexes were bound to the edge of the active gorge without impeding the approach to the catalytic triad. According to this, Pt1 represents a promising compound with potent anticancer properties, high selectivity, and low neurotoxicity.

2',6'-dihydroxy-4'-methoxy Dihydrochalcone Improves the Cognitive Impairment of Alzheimer's Disease: A Structure-activity Relationship Study.

Chalcones and dihydrochalcones present potent inhibition of acetylcholinesterase, currently considered the most efficient approach for symptomatic treatment of Alzheimer's disease. The present study aimed to explore the potential benefits of 2',6'-dihydroxy-4'-methoxy dihydrochalcone on the cognitive deficits of animals submitted to the streptozotocin-induced Alzheimer's model, as well as evaluating the possible mechanisms of action. Learning and memory functions of different groups of animals were submitted to the streptozotocin-induced Alzheimer's model (STZ 2.5 mg/mL, i.c.v.) and subsequently treated with 2',6'-dihydroxy-4'-methoxy dihydrochalcone (DHMDC) administered at doses of 5, 15, and 30 mg/kg (p.o.), respectively. Rivastigmine (0,6 mg/kg, i.p.) and vehicle were evaluated in aversive memory test (inhibitory avoidance test) and spatial memory test (object recognition test). Molecular docking simulations were performed to predict the binding mode of DHMDC at the peripheral site of AChE, to analyze noncovalent enzyme-ligand interactions. DFT calculations were carried out to study well-known acetylcholinesterase inhibitors and DHMDC. DHMDC markedly increased the learning and memory of mice. STZ caused a significant decline of spatial and aversive memories in mice, attenuated by DHMDC (15 and 30 mg/kg). Furthermore, STZ conspicuously increased lipid peroxidation and compromised the antioxidant levels in mice brains. DHMDC pretreatment significantly increased GSH activity and other oxidative stress markers and decreased TBARS level in the brain of STZ administered mice. AChE activity was significantly decreased by DHMDC in the brain of mice. The results together point out that DHMDC may be a useful drug in the management of dementia.

Ligand-based virtual screening, molecular docking, and molecular dynamics of eugenol analogs as potential acetylcholinesterase inhibitors with biological activity against Spodoptera frugiperda.

The development of new, more selective, environmental-friendly insecticide alternatives is in high demand for the control of Spodoptera frugiperda (S. frugiperda). The major objective of this work was to search for new potential S. frugiperda acetylcholinesterase (AChE) inhibitors. A ligand-based virtual screening was initially carried out considering six scaffolds derived from eugenol and the ZINC15, PubChem, and MolPort databases. Subsequently, molecular docking analysis of the selected compounds on the active site and a second region (determined by blind molecular docking) of the AChE of S. frugiperda was performed. Molecular dynamics and Molecular Mechanics Poisson-Boltzmann Surface Area analyses were also applied to improve the docking results. Finally, three new eugenol analogs were evaluated in vitro against S. frugiperda larvae. The virtual screening identified 1609 compounds from the chemical libraries. Control compounds were selected from the interaction fingerprint by molecular docking. Only three new eugenol analogs (1, 3, and 4) were stable at 50ns by molecular dynamics. Compounds 1 and 4 had the best biological activity by diet (LC50 = 0.042mg/mL) and by topical route (LC50 = 0.027mg/mL), respectively. At least three new eugenol derivatives possessed good-to-excellent insecticidal activity against S. frugiperda.

Development of a Capillary Electrophoretic Method for the Determination of Huperzine A Concentration in Vietnamese Huperzia serrata

Huperzine A, isolated from Huperzia serrata, is a potent, specific, and reversible inhibitor of acetylcholinesterase with high efficiency and low toxicity. To evaluate the presence of huperzine A in Vietnamese H serrata, a reliable capillary zone electrophoresis method was developed. The analytical conditions were established using 80 mM ammonium acetate buffer, pH 6.0, hydrodynamic injection at 50 mbar for 5 s, applied voltage of 20 kV, temperature at 25 °C, uncoated fused-silica capillary, 56 cm (50 cm effective length) × 70 µm inner diameter, and ultraviolet detection at 310 nm. The recovery rates ranged from 98.05% to 100.64%, with a relative standard deviation &lt;2%. Good linear regression was observed in the concentration range of 1 to 500 µg/mL, with a correlation coefficient of 0.9994. The limit of detection and limit of quantification were 0.33 and 1.0 µg/mL, respectively. These results demonstrate that this method is simple, selective, and suitable for performing quality control for huperzine A derived from Vietnamese H serrata.

New thiazole and thiazole-chromene hybrids possessing morpholine units: Piperazine-mediated one-pot synthesis of potential acetylcholinesterase inhibitors

In the current study, new morpholine-linked thiazoles were prepared by the reaction of salicylaldehyde derivative, thiosemicarbazide, and α-bromoketones. To mediate the previous three-component reaction, the reaction was conducted using two equiv. of piperazine in dioxane at reflux for 5 h. Using the prior protocol, two series of thiazoles, linked to arene or chromene units, were prepared in good to excellent yields. The new thiazoles were examined as potential inhibitors of acetylcholinesterase at a concentration of 50 µM. When compared to donepezil (inhibition percentage of 92.8%), hybrids 11b and 11c, linked to 6-chloro or 6-bromochromen-3-yl units, gave the best inhibition percentages of 72.3 and 71.5%, respectively. Furthermore, when tested at a concentration of 25 µg/mL, the same hybrids demonstrated the highest DPPH antioxidant activity, with inhibition percentages of 84.1 and 83.2%, respectively, when compared to ascorbic acid (inhibition percentage of 89.5%).

Synthesis, Biological Evaluation, and In Silico Studies of New Acetylcholinesterase Inhibitors Based on Quinoxaline Scaffold.

A quinoxaline scaffold exhibits various bioactivities in pharmacotherapeutic interests. In this research, twelve quinoxaline derivatives were synthesized and evaluated as new acetylcholinesterase inhibitors. We found all compounds showed potent inhibitory activity against acetylcholinesterase (AChE) with IC50 values of 0.077 to 50.080 µM, along with promising predicted drug-likeness and blood–brain barrier (BBB) permeation. In addition, potent butyrylcholinesterase (BChE) inhibitory activity with IC50 values of 14.91 to 60.95 µM was observed in some compounds. Enzyme kinetic study revealed the most potent compound (6c) as a mixed-type AChE inhibitor. No cytotoxicity from the quinoxaline derivatives was noticed in the human neuroblastoma cell line (SHSY5Y). In silico study suggested the compounds preferred the peripheral anionic site (PAS) to the catalytic anionic site (CAS), which was different from AChE inhibitors (tacrine and galanthamine). We had proposed the molecular design guided for quinoxaline derivatives targeting the PAS site. Therefore, the quinoxaline derivatives could offer the lead for the newly developed candidate as potential acetylcholinesterase inhibitors.