Analysis of a Molecular Dynamics Simulation of the Acetylcholinesterase Enzyme and Its Complex with (Axillaridine-A) Inhibitor (original) (raw)
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Molecular dynamics simulation of Axillaridine-A: A potent natural cholinesterase inhibitor
2009
Molecular Dynamics (MD) simulations were carried out for human acetylcholinesterase (hAChE) and its complex with Axillaridine-A, in order to dynamically explore the active site of the protein and the behaviour of the ligand at the peripheral binding site. Simulation of the enzyme alone showed that the active site of AChE is located at the bottom of a deep and narrow cavity whose surface is lined with rings of aromatic residues while Tyr72 is almost perpendicular to the Trp286, which is responsible for stable π-π interactions. The complexation of AChE with Axillaridine-A, results in the reduction of gorge size due to interaction between the ligand and the active site residues. The gorge size was determined by the distance between the center of mass of Glu81 and Trp286. As far as the geometry of the active site is concerned, the presence of ligand in the active site alters its specific conformation, as revealed by stable hydrogen bondings established between amino acids. With the increasing interaction between ligand and the active amino acids, size of the active site of the complex decreases with respect to time. Axillaridine-A, forms stable π-π interactions with the aromatic ring of Tyr124 that results in inhibition of catalytic activity of the enzyme. This π-π interaction keeps the substrate stable at the edge of the catalytic gorge by inhibiting its catalytic activity. The MD results clearly provide an explanation for the binding pattern of bulky steroidal alkaloids at the active site of AChE.
Molecular Dynamics Simulations of Acetylcholinesterase – Beta-Amyloid Peptide Complex
Cybernetics and Information Technologies, 2020
Alzheimer’s Disease (AD) is a neurodegenerative disorder with severe consequences and lethal outcome. One of the pathological hallmarks of the disease is the formation of insoluble intercellular beta-Amyloid (Aβ) plaques. The enzyme ACetylcholinEsterase (AChE) promotes and accelerates the aggregation of toxic Aβ protofibrils progressively converted into plaques. The Peripheral Anionic Site (PAS), part of the binding gorge of AChE, is one of the nucleation centers implicated in the Aβ aggregation. In this study, the Aβ peptide was docked into the PAS and the stability of the formed complex was investigated by molecular dynamics simulation for 1 μs (1000 ns). The complex was stable during the simulation. Apart from PAS, the Aβ peptide makes several additional contacts with AChE. The main residence area of Aβ on the surface of AChE is the region 344-361. This region is next to PAS but far enough to be sterically hindered by dual-site binding AChE inhibitors.
2023
The molecular structures of the lowest-energy conformers of donepezil (C 24 H 29 NO 3), rivastigmine (C 14 H 22 N 2 O 2), and galantamine (C 17 H 21 NO 3), which are extensively used in Alzheimer's disease and other memory disorders, were identified using the Spartan06 program and the MMFF method. The optimized geometries, obtained with the same method, were used as initial data in molecular docking investigations with the Acetylcholinesterase enzyme. The binding modes, binding affinities, and interactions were comparatively determined as consequence of the calculations.
Journal of molecular modeling, 2017
This paper deals with molecular modeling of new therapeutic agents for treating the Alzheimer's disease. The therapeutic line adopted for this study is the cholinergic hypothesis. To modulate positively the cholinergic function through the inhibition of the acetylcholinesterase, a set of candidates was designed from a natural compound extracted from the cashew nutshell liquid, anacardic acid. In silico screening of this chemical library revealed a ligand that is more promising once it is correlated with an active drug through specific topological and electronic descriptors. The protein-ligand docking showed stable binding modes and the binding free energy computed for the active site of the receptor suggests that our ligand presents a potential biological response. Graphical Abstract Representation of the three dimensional structure of the AChE, showing the important binding sites of the Gorge and the conformation of the ligand.
2014
Cholinesterase inhibitors (ChE-Is) are the standard for the therapy of AD associated disorders and are the only class of approved drugs by the Food and Drug Administration (FDA). Additionally, acetylcholinesterase (AChE) is the target for many Alzheimer's dementia drugs which block the function of AChE but have some side effects. Therefore, in this paper, an attempt was made to elucidate cholinesterase inhibition potential of secondary metabolite from Cannabis plant which has negligible or no side effect. Molecular docking of 500 herbal compounds, against AChE, was performed using Autodock 4.2 as per the standard protocols. Molecular dynamics simulations have also been carried out to check stability of binding complex in water for 1000 ps. Our molecular docking and simulation have predicted high binding affinity of secondary metabolite (C 28 H 34 N 2 O 6) to AChE. Further, molecular dynamics simulations for 1000 ps suggest that ligand interaction with the residues Asp72, Tyr70-121-334, and Phe288 of AChE, all of which fall under active site/subsite or binding pocket, might be critical for the inhibitory activity of AChE. This approach might be helpful to understand the selectivity of the given drug molecule in the treatment of Alzheimer's disease. The study provides evidence for consideration of C 28 H 34 N 2 O 6 as a valuable small ligand molecule in treatment and prevention of AD associated disorders and further in vitro and in vivo investigations may prove its therapeutic potential.
Introduction Alzheimer's disease (AD) is a devastating brain disorder characterized by an irreversible loss of memory and damage of cognitive functions. AD typically results in a full deterioration of memory skills and mental activities, leading to the most widespread form of senile dementia and affecting a lot of demented individuals worldwide with increasing tendency [1]. Many etiopathogenic mechanisms including metabolic, genetic, environmental factors, and lifestyle are key pathological features in appearance and progression of the disease [2]. The AD is associated with deficits in cholinergic neurotransmission [3], bio metals dysfunction [4,5], formation of toxic β-amyloid (Aβ) plaques by the deposition of abnormal proteins in the form of these plaques [6], inflammation and increased oxidative stress [7], destabilization of calcium homeostasis [8], and accumulation of tau-protein hyper phosphorylation [9]. Acetylcholine (ACh) is a critical neurotransmitter for specific aspects of brain healthy and cognitive activities. The cholinesterase inhibitors play a vital therapeutic role in elevating ACh levels [10]. That is released at the end of the neuron by the appearance of a nerve impulse, which is transmitted at synapses. Enhancement of the activity of cholinergic neurons seems to be the only way to develop strong medications for reducing disease exacerbation [11]. It is carried out by acetylcholinesterase (AChE) inhibition, the enzyme having control over the hydrolysis acetylcholine [12,13]. The information on crystal structure of AChE is crucial to comprehend its high catalytic effectiveness and atomic basis for the binding of ACh-receptor to recognize ACh [14]. In addition, the clarification of the basic action mechanism of the pharmacological action of these agents would be suitable for further research in the drug design process. The plurality of cholinergic neurotransmission problems is treated by AChE inhibitors, which are the basis of some drugs considered to be the first developed generation drugs to reduce the severity of cognitive disorders [15]. For that reason, the search for new potent acetylcholinesterase inhibitors with improved interactions is highly demanding.
Acetylcholinesterase (AChE) catalyzes the hydrolysis of neurotransmitter acetylcholine to acetate and choline in a synaptic cleft. Deficits in cholinergic neurotransmitters are linked closely with the progression of Alzheimer's disease (AD), which is a neurodegenerative disorder characterized by memory impairment, and a disordered cognitive function. Since the previously approved AChE inhibitors, donepezil (Aricept), galantamine (Reminyl), and rivastigmine (Exelon), have side effects and several studies are being carried out out to develop novel AD drugs, we have applied a three-dimensional quantitative structure−activity relationship (3D QSAR) and structure-based pharmacophore modeling methodologies to identify potential candidate inhibitors against AChE. Herein, 3D QSAR and structure-based pharmacophore models were built from known inhibitors and crystal structures of human AChE in complex with donepezil, galantamine, huperzine A, and huprine W, respectively. The generated models were used as 3D queries to screen new scaffolds from various chemical databases. The hit compounds obtained from the virtual screening were subjected to an assessment of drug-like properties, followed by molecular docking. The final hit compounds were selected based on binding modes and molecular interactions in the active site of the enzyme. Furthermore, molecular dynamics simulations for AChE in complex with the final hits were performed to evaluate that they maintained stable interactions with the active site residues. The binding free energies of the final hits were also calculated using molecular mechanics/Poisson-Boltzmann surface area method. Taken together, we proposed that these hits can be promising candidates for anti-AD drugs.
Trends in Sciences
Alzheimer’s disease (AD) is a major public health problem worldwide due to an increase in the elderly population. The current pharmacotherapy for the early stages of AD is mainly dependent on cholinesterase inhibitors. Two of the most commonly used anti-AD drugs, donepezil (DPZ) and galantamine (GLM), are selective inhibitors for human acetylcholinesterase (hAChE). However, the inhibitory activity of DPZ on hAChE was more potent than GLM by ~85 times. To better understand the molecular basis for differences in mode of inhibition of hAChE by both drugs, molecular dynamics (MD) simulation was performed. The results showed that the active site residues of hAChE/DPZ had the higher hydrogen bond occupancies as compared to hAChE/GLM. Nevertheless, the 2 drugs directly formed hydrogen bonds with the catalytic residue H447 of hAChE. The per-residue free energy decomposition suggested that DPZ interacted with the residues in peripheral anionic site of hAChE, resulting in the greater binding ...
chemistry and biodiversity, 2023
Researchers have focused on inhibiting acetylcholinesterase for Alzheimer's disease treatment. In this study, some novel AChE inhibitors were synthesized using hydroxypyridin-4-one plus benzylpiperidine scaffolds which were evaluated using Ellman's method. Accordingly, ((1-(4-methoxyphenethyl)piperidin-4yl)amino)methyl)-5-hydroxy-1-methylpyridin-4(1H)-one (VII d) showed weaker but promising AChE inhibition compared to donepezil (IC 50 = 143.090 nM). The average RMSD values of VII d was found to be 2.25 indicated less structural changes in the active site residues. The phenyl group of the phenyl-ethyl-Npiperidine moiety of VII d formed hydrophobic interactions with Trp285 and Tyr340. There was a π-cation interaction between nitrogen atom of piperidine ring and Phe294. Another π-cation interaction was found between type 2 amine of linker and Trp85. Piperidine ring interacted with Tyr336, Tyr123, and Phe337 through hydrophobic interactions. Indeed, the VII d was predicted to be absorbed across the gastrointestinal tract, though it may be pumped out by P-gp. Indeed, VIId can permeate through the blood brain barrier. MD simulation studies revealed that benzyloxy moiety plays a role similar to benzylpiperidine moiety of donepezil in binding to the active site residues. Also, carbonyl group functioned similar to indanone ketone group. Overall; further research on VII d may lead to introduction of a novel class of AChE inhibitors.
Journal of Chemistry, 2013
Neurodegenerative disorders are related to the progressive loss of structure or function and, eventually, death of neurons. These processes are responsible for diseases like Parkinson's, Alzheimer's, and Huntington's, and the main molecular target for the drug design against these illnesses today is the enzyme acetylcholinesterase (AChE). Following this line, in the present work, we applied docking techniques to study some piperidine derivative inhibitors of AChE and further propose structures of six new AChE inhibitors as potential new drugs against neurodegenerative disorders. The best inhibitor proposed was submitted to additional molecular dynamics simulations steps.