Binding Site Acetylcholinesterase Research Articles

Synthesis, Antiacetylcholinesterase Activity, and Molecular Dynamics Simulation of Aporphine-benzylpyridinium Conjugates.

A series of aporphines conjugated with an N-benzylpyridinium moiety through an amide-bond linkage were synthesized and evaluated for their acetylcholinesterase (AChE) inhibitory activity. The conjugation of the N-benzylpyridinium group significantly enhanced the AChE inhibitory activity of the core aporphine. The halogen substituents on the benzyl group affected the activity of the conjugates. Both (S)- and (R)-enantiomers of three conjugates with low IC50 values were synthesized and evaluated for their activities. All (S)-enantiomers exhibited higher activity than the corresponding (R)-enantiomers. The (S)-enantiomer of 2-chlorobenzylpyridinium-containing aporphine was the most potent inhibitor in this study with an IC50 value of 0.06 ± 0.003 μM. Molecular dynamics simulation analysis revealed that both enantiomers can interact with the AChE binding site, whereas the (S)-enantiomer possessed slightly stronger interaction than the (R)-enantiomer, presumably because of their different orientations, as evidenced by molecular docking. The N-benzylpyridinium dehydroaporphine conjugates were also synthesized but were less active than the corresponding aporphine conjugates.

Design and synthesis of ligustrazine derivatives as potential anti-Alzheimer’s agents

A novel series of ligustrazine derivatives was designed, synthesized, and evaluated as acetylcholinesterase (AChE) and butylcholinesterase (BuChE) inhibitors for the treatment of Alzheimer’s disease (AD). In vitro studies displayed that some of the synthesized compounds revealed promising AChE and BuChE inhibitory effects. Particularly, compounds E12 and E27, indicated highly AChE inhibitory activity with IC50 values of 1.85 μM and 0.98 μM, respectively and showed noteworthy protective effects against on glutamate-induced SH-SY5Y cells damage at 1 μM and 10 μM concentrations. Furthermore, molecular simulation docking elucidates compounds E12 and E27 interacting with residues in the binding site of AChE (PDB code: 4EY7) and BuChE (PDB code: 1P0I), emphasizing the protein residues that participate in the main interactions with the two targets. Taken together, these results revealed that compounds E12 and E27 might be potential lead compounds for further structure optimization in the drug-discovery process against AD.

Alzheimer Hastalığında İlacın Yeniden Kullanım İçin Hesaplamalı Yaklaşımlar

Alzheimer's disease is a progressive age-related brain disorder. It causes gradual memory loss, changes in personality traits, confusion, impaired thinking, and mood changes Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitors have been chosen for the treatment of Alzheimer’s disease. Dual cholinesterase inhibitors have become a new hotspot in the investigation of anti-Alzheimer's drugs. The current study was designed to identify inhibitors for both AChE and BuChE enzymes using computational approaches to accelerate the process of identifying an effective treatment for Alzheimer. From the available drugs, we selected families of the aspirin and imatinib. After the adoption of molecular docking, we found that fendosal from aspirin group and Flumatinib from the Imatinib group are the most active compounds. The docking scores for fendosal was -8.160 kcal/mol against AChE while Flumatinib had -9.433 kcal/mol and -9.541 kcal/mol scores with BuChE and AChE, respectively. The 10 ns molecular dynamics simulation for fendosal and flumatinib against AChE and BuChE was performed to evaluate the drug's ability to remain stable within the binding sites of AChE and BuChE with the aid of RMSD and RMSF plots. These results revealed that Flumatinib and fendosal are good inhibitors for both BuChE and AChE, which could be used in vivo and in vitro studies to improve outcomes.

Two new dilactonized glycerol glycosides of the dual anticholinesterase active extract from Ocotea daphnifolia using bioguided fractionation and molecular docking studies.

The dual inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) is considered as an important strategy for the treatment of Alzheimer's disease. In this study, we applied the bioguided fractionations of Ocotea daphinifolia ethyl acetate active extract to furnish a fraction with high inhibitory activity for AChE and BuChE (82% and 92%, respectively). High-performance liquid chromatography semipreparative purification of this fraction provided two new natural products: 1-β-D-galactopyranosyl-glycerol-2,3-heptanedionate, (1) whose complete chemical structural elucidation was made with spectrometric analysis (MS, 1D, and 2D NMR) and its minor derivative 1-β-D-gulopyranosyl-glycerol-2,3-heptanedionate; (2) which could be characterized by 2D 1 H-13 C heteronuclear single-quantum correlation spectra analysis. Investigation of the intermolecular interactions with cholinesterases was carried out by molecular docking studies, and results suggested that both compounds are capable to interact with the catalytic site of both enzymes. Compounds 1 and 2 interact with residues of catalytic domains and the peripheral anionic binding site of AChE and BuChE. The results are comparable to those achieved with rivastigmine and galantamine. Thus, this study provides evidence for consideration of the glycosylglycerol from O. daphnifolia as new valuable dual cholinesterases inhibitor.

The in silico and in vitro analysis of donepezil derivatives for Anopheles acetylcholinesterase inhibition.

Current studies on Anopheles anticholinesterase insecticides are focusing on identifying agents with high selectivity towards Anopheles over mammalian targets. Acetylcholinesterase (AChE) from electric eel is often used as the bioequivalent enzyme to study ligands designed for activity and inhibition in human. In this study, previously identified derivatives of a potent AChE, donepezil, that have exhibited low activity on electric eel AChE were assessed for potential AChE-based larvicidal effects on four African malaria vectors; An. funestus, An. arabiensis, An. gambiae and An. coluzzii. This led to the identification of four larvicidal agents with a lead molecule, 1-benzyl-N-(thiazol-2-yl) piperidine-4-carboxamide 2 showing selectivity for An. arabiensis as a larvicidal AChE agent. Differential activities of this molecule on An. arabiensis and electric eel AChE targets were studied through molecular modelling. Homology modelling was used to generate a three-dimensional structure of the An. arabiensis AChE for this binding assay. The conformation of this molecule and corresponding interactions with the AChE catalytic site was markedly different between the two targets. Assessment of the differences between the AChE binding sites from electric eel, human and Anopheles revealed that the electric eel and human AChE proteins were very similar. In contrast, Anopheles AChE had a smaller cysteine residue in place of bulky phenylalanine group at the entrance to the catalytic site, and a smaller aspartic acid residue at the base of the active site gorge, in place of the bulky tyrosine residues. Results from this study suggest that this difference affects the ligand orientation and corresponding interactions at the catalytic site. The lead molecule 2 also formed more favourable interactions with An. arabiensis AChE model than other Anopheles AChE targets, possibly explaining the observed selectivity among other assessed Anopheles species. This study suggests that 1-benzyl-N-(thiazol-2-yl) piperidine-4-carboxamide 2 may be a lead compound for designing novel insecticides against Anopheles vectors with reduced toxic potential on humans.

Three to Tango: Inhibitory Effect of Quercetin and Apigenin on Acetylcholinesterase, Amyloid-β Aggregation and Acetylcholinesterase-Amyloid Interaction.

One of the pathological hallmarks of Alzheimer's disease (AD) is the formation of amyloid-β plaques. Since acetylcholinesterase (AChE) promotes the formation of such plaques, the inhibition of this enzyme could slow down the progression of amyloid-β aggregation, hence being complementary to the palliative treatment of cholinergic decline. Antiaggregation assays performed for apigenin and quercetin, which are polyphenolic compounds that exhibit inhibitory properties against the formation of amyloid plaques, reveal distinct inhibitory effects of these compounds on Aβ40 aggregation in the presence and absence of AChE. Furthermore, the analysis of the amyloid fibers formed in the presence of these flavonoids suggests that the Aβ40 aggregates present different quaternary structures, viz., smaller molecular assemblies are generated. In agreement with a noncompetitive inhibition of AChE, molecular modeling studies indicate that these effects may be due to the binding of apigenin and quercetin at the peripheral binding site of AChE. Since apigenin and quercetin can also reduce the generation of reactive oxygen species, the data achieved suggest that multitarget catechol-type compounds may be used for the simultaneous treatment of various biological hallmarks of AD.

Molecular engineering and activity improvement of acetylcholinesterase inhibitors: Insights from 3D-QSAR, docking, and molecular dynamics simulation studies

The carbamate molecule rivastigmine was found to possess promising anti-acetylcholinesterase activity, enabling to target and occupy choline binding sites, and as a result, widely used to improve the treatment of Alzheimer's disease (AD). Higher dose of rivastigmine indicates rapid onset but more adverse effects, such as the large fluctuations in plasma concentration level and frequent incidence of gastrointestinal side effect. To solve the dilemma, we developed a three-dimensional quantitative structure-activity relationship (3D-QSAR), docking and molecular dynamics (MD) simulation strategy to construct a dismountable nanoplatform of inhibitor engineering, verification and application for improving the inhibitory activity per unit concentration. With the aid of 3D-QSAR method, we constructed a model by using 25 molecules reported, and verified well the rationality of these QSAR models by non-cross validation coefficient (r2 = 0.902). Docking and MD results show that rivastigmine, as a control, does target exactly the binding sites of acetylcholinesterase, those already observed experimentally, in turn, confirming the reliability of the present 3D-QSAR results. The method suggests that groups with electron-donating chemical property can improve the inhibitory activity, and screens out two novel inhibitors L-1 and L-2 with more activity from database (about 8000 compounds). Moreover, L-1 and L-2 not only target exactly the same binding sites of acetylcholinesterase as the rivastigmine does, but also hold stronger binding energy, showing a more powerful inhibitory ability. More broadly, this work showcases an approach in the engineering of carbamate inhibitors to enhance their inhibitory activity using electron-donating groups, which simplifies the design process of complex bioactive molecules.

Molecular Interactions between an Enzyme and Its Inhibitor for Selective Detection of Limonene.

Researchers widely apply enzyme inhibition to chemicals such as pesticides, nerve gases, and anti-Alzheimer's drugs. However, application of enzyme inhibition to odorant sensors is less common because the corresponding reaction mechanisms have not yet been clarified in detail. In this study, we propose a new strategy for highly selective detection of odorant molecules by using an inhibitor-specific enzyme. As an example, we analyzed the selective interactions between acetylcholinesterase (AChE) and limonene─the major odorant of citrus and an AChE inhibitor─using molecular dynamics simulations. In these simulations, limonene was found to be captured at specific binding sites of AChE by modifying the binding site of acetylcholine (ACh), which induced inhibition of the catalytic activity of AChE toward ACh hydrolysis. We confirmed the simulation results by experiments using an ion-sensitive field-effect transistor, and the degree of inhibition of ACh hydrolysis depended on the limonene concentration. Accordingly, we quantitatively detected limonene at a detection limit of 5.7 μM. We furthermore distinguished the response signals to limonene from those to other odorants, such as pinene and perillic acid. Researchers will use our proposed odorant detection method for other odorant-enzyme combinations and applications of miniaturized odorant-sensing systems based on rapid testing.

Growth Optimization and Secondary Metabolites Evaluation of Anabaena variabilis for Acetylcholinesterase Inhibition Activity.

Cyanobacteria comprise a good natural resource of a potential variety of neuro-chemicals, including acetylcholinesterase inhibitors essential for Alzheimer’s disease treatment. Accordingly, eight different cyanobacterial species were isolated, identified, and evaluated on their growth on different standard nutrient media. It was found that the modified Navicula medium supported the highest growth of the test cyanobacteria. The effects of methylene chloride/methanol crude extracts of the test cyanobacteria on acetylcholinesterase activity were examined and compared. Anabaena variabilis (KU696637.1) crude extract recorded the highest acetylcholinesterase inhibition (62 ± 1.3%). Navicula medium chemical components were optimized through a Plackett–Burman factorial design. The biomass of Anabaena variabilis increased significantly when grown on the optimized medium compared to that of control. The chemical analysis of the fractions derived from Anabaena variabilis showed the presence of two compounds in significant amounts: the flavonoid 5,7-dihydroxy-2-phenyl-4H-chrome-4-one and the alkaloid 4-phenyl-2-(pyridin-3-yl) quinazoline. Molecular docking studies revealed that both compounds interact with the allosteric binding site of acetylcholinesterase at the periphery with π-π stackings with Tyr341 and Trp286 with good, predicted partition coefficient. The compounds obtained from this study open the door for promising drug candidates to treat Alzheimer’s disease for their better pharmacodynamics and pharmacokinetic properties.

Potential of Bursera graveolens essential oil for controlling bean weevil infestations: Toxicity, repellence, and action targets

Plant essential oils are promising tools for the management of insect infestations in stored beans. However, how these biorational products exert their insecticidal actions remains unknow. Here, we evaluated the insecticidal and repellent potential of Bursera graveolens essential oil against the bean weevil species Acanthoscelides obtectus and Zabrotes subfasciatus. By using chemical and in silico analyses, we evaluated the molecular interactions of the essential oil constituents with two potential physiological targets in stored beans: acetylcholinesterase (AChE) enzymes and transient receptor potential (TRP) channels. Our results revealed limonene (44%), phellandrene (24%), cymene (13%), and menthofuran (11%) as the major constituents of the essential oil. Both bean weevil species were similarly killed by the fumigant essential oil. However, while Z. subfasciatus individuals were repelled only at high essential oil concentrations (LC95 = 156 μL/L), the essential oil LC15 (44 μL/L) was enough to repel A. obtectus individuals. Our computational predictions revealed that all essential oil constituents formed stable molecular interactions (binding affinity < −5.5 kcal/mol) with the binding sites of acetylcholinesterase and TRP channels, suggesting the involvement of these targets in the essential oil actions. Altogether, our findings show that B. graveolens essential oil may exert its insecticidal actions by disrupting the functions of AChE and TRP channels and that it may be used as an alternative tool for the control of bean weevils

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.

Deciphering the Behavioral Response of Meloidogyne incognita and Fusarium oxysporum Toward Mustard Essential Oil.

Environmental concerns related to synthetic pesticides and the emphasis on the adoption of an integrated pest management concept as a cardinal principle have strengthened the focus of global research and development on botanical pesticides. A scientific understanding of the mode of action of biomolecules over a range of pests is key to the successful development of biopesticides. The present investigation focuses on the in silico protein-ligand interactions of allyl isothiocyanate (AITC), a major constituent of black mustard (Brassica nigra) essential oil (MEO) against two pests, namely, Meloidogyne incognita (Mi) and Fusarium oxysporum f. sp. lycopersici (Fol), that cause severe yield losses in agricultural crops, especially in vegetables. The in vitro bioassay results of MEO against Mi exhibited an exposure time dependent on the lethal concentration causing 50% mortality (LC50) values of 47.7, 30.3, and 20.4 μg ml−1 at 24, 48, and 72 h of exposure, respectively. The study revealed short-term nematostatic activity at lower concentrations, with nematicidal activity at higher concentrations upon prolonged exposure. Black mustard essential oil displayed excellent in vitro Fol mycelial growth inhibition, with an effective concentration to cause 50% inhibition (EC50) value of 6.42 μg ml−1. In order to decipher the mechanism of action of MEO, its major component, AITC (87.6%), which was identified by gas chromatography–mass spectrometry (GC-MS), was subjected to in silico docking and simulation studies against seven and eight putative target proteins of Mi and Fol, respectively. Allyl isothiocyanate exhibited the highest binding affinity with the binding sites of acetyl cholinesterase (AChE), followed by odorant response gene-1 (ODR1) and neuropeptide G-protein coupled receptor (nGPCR) in Mi, suggesting the possible suppression of neurotransmission and chemosensing functions. Among the target proteins of Fol, AITC was the most effective protein in blocking chitin synthase (CS), followed by 2,3-dihydroxy benzoic acid decarboxylase (6m53) and trypsinase (1try), thus inferring these as the principal molecular targets of fungal growth. Taken together, the study establishes the potential of MEO as a novel biopesticide lead, which will be utilized further to manage the Mi–Fol disease complex.

Mannich reaction derived novel boron complexes with amine-bis(phenolate) ligands: Synthesis, spectroscopy and in vitro/in silico biological studies

The amine-bis(phenolate) ligands was prepared through a Mannich reaction utilizing two equivalents of 2,4-di-tert-butylphenol or 4-tert-butylphenol, two equivalents of formaldehyde and a single equivalent of 2-aminoethyl diphenylborinate as primary amine. This work deals with the synthesis and evaluation of new (B←N) and (B-O) units containing amine-bis(phenolate) boron complexes designed by combination of amine-bis(phenolate) ligands and various boronic acids in toluene reflux using a Dean-Stark apparatus to remove water formed as a by-product. The newly synthesized amine-bis(phenolate) ligands and their boron complexes were characterized using elemental analysis, and their probable structures were proposed based on 1H and 13C NMR, FT-IR, UV-Vis spectroscopy and LC-MS/MS spectrometry. The inhibition effects of the synthesized compounds on acetylcholinesterase (AChE) activity in vitro and their radical scavenging activities were evaluated. The AChE was effectively inhibited by compounds, with KI values in the range from 5.48 ± 0.65 to 40.56 ± 4.42 µM. The (L1B4) has more inhibition effect on AChE with KI value (6.37 ± 1.50 µM) in (L2) series, while (L2B4) has an inhibition effect with KI (5.48 ± 0.65 µM) in (L2) series. Also, the compounds showed about 18-45% DPPH and 26-85% ABTS radical scavenging activity. On the other hand, butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT) and Trolox showed about 72-96% DPPH and 94-96% ABTS radical scavenging activity, respectively in the same concentration (25-30 µg/mL). Besides, the (L1B4), (L1B5), and (L2B4) determined as the most active inhibitors were docked into the binding site of AChE to find the binding interactions of the boron complexes with the protein.

Rational design of novel benzisoxazole derivatives with acetylcholinesterase inhibitory and serotoninergic 5-HT4 receptors activities for the treatment of Alzheimer\u2019s disease

A rigidification strategy was applied to the preclinical candidate donecopride, an acetylcholinesterase inhibitor possessing 5-HT4R agonist activity. Inspired by promising bioactive benzisoxazole compounds, we have conducted a pharmacomodulation study to generate a novel series of multitarget directed ligands. The chemical synthesis of the ligand was optimized and compounds were evaluated in vitro against each target and in cellulo. Structure-activity relationship was supported by docking analysis in human acetylcholinesterase binding site. Among the synthesized compounds, we have identified a novel hybrid 32a (3-[2-[1-(cyclohexylmethyl)-4-piperidyl]ethyl]-4-methoxy-1,2-benzoxazole) able to display nanomolar acetylcholinesterase inhibitory effects and nanomolar Ki for 5-HT4R.

Embelin, a Potent Molecule for Alzheimer's Disease: A Proof of Concept From Blood-Brain Barrier Permeability, Acetylcholinesterase Inhibition and Molecular Docking Studies.

Embelin is well-known in ethnomedicine and reported to have central nervous system activities. However, there is no report on blood-brain barrier (BBB) permeability of embelin. Here the BBB permeability of embelin was evaluated using in vitro primary porcine brain endothelial cell (PBEC) model of the BBB. Embelin was also evaluated for acetylcholinesterase (AChE) inhibitory activity and docking prediction for interaction with AChE and amyloid beta (Aβ) binding sites. Embelin was found to be non-toxic to the PBECs and did not disturb the PBEC barrier function. The PBECs showed restrictive tight junctions with average transendothelial electrical resistance of 365.37 ± 113.00 Ω.cm2, for monolayers used for permeability assays. Permeability assays were conducted from apical-to-basolateral direction (blood-to-brain side). Embelin showed apparent permeability (Papp) value of 35.46 ± 20.33 × 10−6 cm/s with 85.53% recovery. In vitro AChE inhibitory assay demonstrated that embelin could inhibit the enzyme. Molecular docking study showed that embelin binds well to active site of AChE with CDOCKER interaction energy of −65.75 kcal/mol which correlates with the in vitro results. Docking of embelin with Aβ peptides also revealed the promising binding with low CDOCKER interaction energy. Thus, findings from this study indicate that embelin could be a suitable molecule to be further developed as therapeutic molecule to treat neurological disorders particularly Alzheimer's disease.

In vitro and in silico evaluation of fucosterol from Sargassum horridum as potential human acetylcholinesterase inhibitor

The fucosterol has been reported numerous biological activities. In this study, the activity in vitro of the fucosterol from Sargassum horridum as potential human acetylcholinesterase inhibitor was evaluated. The structural identification was obtained by nuclear magnetic resonance (NMR) spectroscopy and based on experimental data, we combined docking and molecular dynamics simulations coupled to the molecular-mechanics-generalized-born-surface-area approach to evaluating the structural and energetic basis for the molecular recognition of fucosterol and neostigmine at the binding site of acetylcholinesterase (AChE). In addition, the Lineweaver–Burk plot showed the nature of a non-competitive inhibition. The maximum velocity (Vmax) and the constant of Michaelis–Menten (Km) estimated for fucosterol (0.006 µM) were 0.015 1/Vo (ΔA/h and 6.399 1/[ACh] mM−1, respectively. While, for neostigmine (0.14 µM), the Vmax was 0.022 1/Vo (ΔA/h) and Km of 6.726 1/[ACh] mM−1, these results showed a more effective inhibition by fucosterol respect to neostigmine. Structural analysis revealed that neostigmine reaches the AChE binding site reported elsewhere, whereas fucosterol can act as a no-competitive and competitive acetylcholinesterase inhibitor, in agree with kinetic enzymatic experiments. Binding free energy calculations revealed that fucosterol reaches the acetylcholinesterase binding site with higher affinity than neostigmine, which is according to experimental results. Whereas the per-residue decomposition free energy analysis let us identify crucial residues involved in the molecular recognition of ligands by AChE. Results corroborate the ability of theoretical methods to provide crucial information at the atomic level about energetic and structural differences in the binding interaction and affinity from fucosterol with AChE.Communicated by Ramaswamy H. Sarma

Design, synthesis and bioevaluation of tricyclic fused ring system as dual binding site acetylcholinesterase inhibitors

Due to recently discovered non-classical acetylcholinesterase (AChE) function, dual binding-site AChE inhibitors have acquired a paramount attention of drug designing researchers. The unique structural arrangements of AChE peripheral anionic site (PAS) and catalytic site (CAS) joined by a narrow gorge, prompted us to design the inhibitors that can interact with dual binding sites of AChE. Eighteen homo- and heterodimers of desloratadine and carbazole (already available tricyclic building blocks) were synthesized and tested for their inhibition potential against electric eel acetylcholinesterase (eeAChE) and equine serum butyrylcholinesterase (eqBChE). We identified a six-carbon tether heterodimer of desloratadine and indanedione based tricyclic dihydropyrimidine (4c) as potent and selective inhibitor of eeAChE with IC50 value of 0.09 ± 0.003 μM and 1.04 ± 0.08 μM (for eqBChE) with selectivity index of 11.1. Binding pose analysis of potent inhibitors suggest that tricyclic ring is well accommodated into the AChE active site through hydrophobic interactions with Trp84 and Trp279. The indanone ring of most active heterodimer 4b is stabilized into the bottom of the gorge and forms hydrogen bonding interactions with the important catalytic triad residue Ser200.

Combined QSAR, molecular docking and molecular dynamics study on new Acetylcholinesterase and Butyrylcholinesterase inhibitors

Background and purposeThis work deals with several molecular modeling methods used to discover new therapeutic agents for treating the Alzheimer’s disease (AD). The cholinergic hypothesis was initially presented over 30 years ago and suggests that a dysfunction of acetylcholine containing neurons in the brain. Acetylcholinesterase (AChE) and Butyrylcholinesterase (BuChE) are of the keys targets of drugs for treating AD. MethodsQSAR, Molecular Docking/Dynamics and ADME properties were carried out in order to study 36 compounds that belong to the 4-[(diethylamino)methyl]-phenol derivatives and test their AChE and BuChE inhibitory activities, MOE, HyperChem and others softwares were used to find the best compounds with high affinity. ResultsThe QSAR models exhibited good statistical values for both targets AChE (R2adj = 0.660, q2 = 0.70, F-ratio = 18.008) and BuChE (R2adj = 0.726, q2 = 0.75, F-ratio = 31.864). The interactions between the studied inhibitors and our targets were further explored through molecular docking and molecular dynamics simulations. A few key residues (TRP279, TYR334, PHE330 and TRP84) at the binding site of AChE and key residues (HIS438, TYR332, PHE329 and TRP82) at the binding site of BuChE were identified. ConclusionBased on this study compounds 23 and 28 have no violated Lipinski’s rule of five and thus, showing the possibility of being potential candidates for further studies in drug development process against the AChE and BuChE targets respectively.

Phytochemical analysis, molecular docking and antiamnesic effects of methanolic extract of Silybum marianum (L.) Gaertn seeds in scopolamine induced memory impairment in mice

Ethnopharmacological relevanceSilybum marianum (L.) Gaertn and its main component silymarin have been extensively studied and have been found effective in various neurological disorders. Aims of the studyThe aim of the current study is to identify phytoconstituents in the methanolic extract (Me. Ext) of Silybum marianum (L.) Gaertn seeds and to study in-vivo the anti-amnesic effects along with in vitro antioxidant and acetylcholinesterase (AChE) and buteryl cholinesterase (BChE) inhibition potential. Induced fir docking (IFD) results have confirmed that quercetin, morin and rutin showed good affinity when docked into AChE binding site. Materials and methodsThe present study investigates the in-vitro AChE and BChE inhibition potential of the Me-Ext of Silybum marianum (L.) Gaertn at various concentrations (31.25, 62.50, 125, 250, 500, 1000µg/mL) using Ellman's spectrophotometric analysis, while antioxidant potential against DPPH and ABTS were determined using Brand-Williams spectrophotometric method. Furthermore, the in-vivo anti-amnesic effects of Me. Ext at the dose level of 50, 100 and 200mg/kg were also evaluated using scopolamine -induced memory impairment in mice in the novel object recognition test (NORT) and Y-maze test. ResultsThe Me. Ext showed a concentration dependent inhibition of AChE and BChE with IC50 values of 110 and 130µg/mL respectively and antioxidant activity against DPPH and ABTS with IC50 values 280 and 220µg/mL, respectively. In mice, Me. Ext reversed the amnesia induced by scopolamine as indicated by a dose-dependent increase in spontaneous alternation performance in the Y-maze task (p< 0.05 versus scopolamine) and increase in the discrimination index in the NORT comparable to the standard drug donepezil 2mg/kg. HPLC-UV analysis showed the presence of quercetin, rutin and morin. Induced fit docking (IFD) was performed using quercetin, rutin and morin, Glide Gscore and IFD score of all compounds were consistent with their experimental AChE inhibitory activities. ConclusionThe results indicate that Silybum marianum (L.) Gaertn could be a new source for the isolation of phytoconstituents useful in cognition and memory disorders such as Alzheimer's disease.

The discovery of new acetylcholinesterase inhibitors derived from pharmacophore modeling, virtual screening, docking simulation and bioassays.

Hyperactivity of acetylcholinesterase (AChE) in the brain is the immediate cause of Alzheimer's disease (AD), which is one of the most prevalent fatal diseases afflicting numerous older people. In this research, an in silico study was carried out to find potential AChE inhibitors from a large chemical library. With clustering and lots of comprehensive analysis, some molecules were screened using in vitro bioassays. The IC50 values against AChE ranged from 33.620 to 101.570 μM, while the inhibition ratios at 50 μM ranged from 11.37% to 77.35%. The binding mode between the inhibitor and the binding sites of AChE was studied. Four residues (Tyr133, Tyr124, Ser203 and Trp86) were suggested to be crucial because they can form hydrogen bonds with the ligand. Therefore, ZYQ1 and its derivatives might represent a promising starting point for the development of highly potent lead compounds for the treatment of AD.