Molecular Insights into the Conformational and Binding Behaviors of Human Serum Albumin Induced by Surface-Active Ionic Liquids.

Extensive research has been carried out to investigate the stability and function of human serum albumin (HSA) when exposed to surface-active ionic liquids (SAILs) with different head groups (imidazolium, morpholinium, and pyridinium) and alkyl chain lengths (ranging from decyl to tetradecyl). Analysis of the protein fluorescence spectra indicates noticeable changes in the secondary structure of HSA with varying concentrations of all SAILs tested. Helicity calculations based on the Fourier transform infrared (FTIR) data show that HSA becomes more organized at the micellar concentration of SAILs, leading to an increased protein activity at this level. Small-angle neutron scattering (SANS) data confirm the formation of a bead-necklace structure between the SAILs and HSA. Atomistic molecular dynamics (MD) simulation results identify several hotspots on the protein surface for interaction with SAIL, which results in the modulation of protein conformational fluctuation and stability. Furthermore, fluorescence resonance energy transfer (FRET) experiments with the intramolecular charge transfer (ICT) probe trans-ethyl p-(dimethylamino) cinnamate (EDAC) demonstrate that higher alkyl chain lengths and SAIL concentrations result in a significantly increased energy transfer efficiency. The findings of this study provide a detailed molecular-level understanding of how the protein structure and function are affected by the presence of SAILs, with potential implications for a wide range of applications involving protein-SAIL composite systems.

BODIPY(aryl)iodonium salts in the efficient synthesis of diversely functionalized BODIPYs and selective detection of serum albumin.

BODIPY(aryl)iodonium salts were readily accessible from the high-yielding reaction of BODIPY with iodoarenes or hydroxyl(tosyloxy)iodoarenes in the presence of m-CPBA. The prepared BODIPY(aryl)iodonium salts bearing substituents of varied electronic nature were utilized for the direct syntheses of thiocyanate, azide, amine and acrylate functionalized BODIPYs and ß,ß'-bis-BODIPYs. The regioselective syntheses of α-piperidinyl and ß-piperidinyl substituted BODIPYs were achieved through the reaction of BODIPY(aryl)iodonium salts with piperidine in the absence and presence of copper(I). Expeditious and high yielding (79-82%) synthesis of ß,ß'-bis-BODIPYs was also developed through the palladium-catalyzed reductive coupling of the easily accessible BODIPY(aryl)iodonium salts. Some of the indole-appended BODIPYs and bis-BODIPYs displayed strong absorption in the visible region (∼610 nm). The BODIPY(aryl)iodonium salts also showed significant binding with serum albumin and were observed to be selective serum protein sensors with estimated limits of detection as low as 7 µg mL-1 in some cases.

Many-body Effects on Electronic Transport in Molecular Junctions: A Quantum Perspective.

This concept delves into quantum particle transport at the nanoscale, with a particular focus on how electrons move through molecular circuits. The thriving field of single molecular electronics benefits from the unique electrical and other properties of nanostructures. It concentrates on single molecular junctions that serve as bridges between electrodes. In this context, the electronic correlation-induced many-body effect gives rise to resonant states. These states, along with conductance, depend on electron spin. Thus, the field acts as a bridge between quantum and macroscopic worlds, unveiling unique behaviors of electrons. Additionally, external factors, such as magnetic fields and voltages, offer means to control the electron correlation in these junctions.

Exploring the impact of novel thiazole-pyrazole fused benzo-coumarin derivatives on human serum albumin: Synthesis, photophysical properties, anti-cholinergic activity, and interaction studies.

Derivatives of thiazole-pyrazole fused benzo-coumarin compounds were successfully synthesized and characterized, followed by a comprehensive spectroscopic investigation on various photophysical properties in different media. The multipronged approach using steady state and time resolved fluorescence spectroscopy pointed out the impact of substitution in the estimated spectroscopic and other physicochemical properties of the systems. Further, the evaluation of anti-acetylcholinesterase (anti-AChE) activity yielded significant insight into the therapeutic potential of the synthesized coumarinyl compounds for the treatment of Alzheimer's disease (AD). The findings revealed a non-competitive mode of inhibition mechanism, with an estimated IC50 value of 67.72 ± 2.00 nM observed for one of the investigated systems as AChE inhibitor. Notably, this value is even lower than that of an FDA-approved AD drug Donepezil (DON), indicating the enhanced potency of the coumarin derivatives in inhibiting AChE. Interestingly, significant diminution in inhibition was observed in presence of human serum albumin (HSA) as evidenced by the relative increase in IC50 value by 8 âˆ¼ 39 % in different cases, which emphasized the role of albumin proteins to control therapeutic efficacies of potential medications. In-depth spectroscopic and in-silico analysis quantified the nature of interactions of the investigated systems with HSA and AChE. Overall, the outcomes of this study provide significant understanding into the biophysical characteristics of novel thiazole-pyrazole fused benzo-coumarin systems, which could aid in the development of new cholinergic agents for the treatment of AD and materials based on coumarin motifs.

Iodine(III)-promoted regioselective and efficient synthesis of ß-triazolyl BODIPYs for the selective recognition of nickel ions and bovine serum albumin.

Various ß-triazolyl tethered BODIPYs were efficiently prepared in a sequential one-pot protocol involving the initial reaction of BODIPY with iodobenzene diacetate (IBD) and sodium azide to in situ generate BODIPY azides followed by a copper-catalyzed azide-alkyne cycloaddition reaction. Under the optimized reaction conditions, various ß-triazolyl BODIPYs 5a-i were successfully prepared in good yields and adequately characterized by using UV, NMR, mass spectral data and XRD analyses. The UV-Visible spectra of the prepared ß-triazolyl BODIPYs 5a-i showed intense absorption bands (514-545 nm) with a 13-44 nm red shift when compared with those of the parent BODIPY. The selective recognition of compound 5d towards Ni2+ ions (detection limit 0.26 nM) led to significant quenching in the fluorescence intensity over other selected bivalent metal ions. The complex formed between 5d and Ni2+ in a stoichiometry of 2 : 1 was found to have a binding constant of 7.5 × 105 M-1. The fluorescence of compound 5i gets enhanced gradually upon interaction with bovine serum albumin due to its selective and high binding affinity (1.25 × 105 M-1) with protein and a concomitant decrease in the total non-radiative decay rate.

Auxiliary Therapeutic Role of Cholinergic Agents: Mechanistic Insights into the Antioxidant Behavior of Alzheimer's Disease Drugs.

Repurposing of existing drugs toward new therapeutic use(s) has become an emergent area of research in current times. In this context, the antioxidant behavior of eight cholinergic drugs used in the treatment of Alzheimer's disease (AD) was investigated theoretically. The low bond dissociation enthalpy values in all of the compounds advocated for the hydrogen atom transfer mechanism toward the observed antioxidant behavior. The kinetic study for the reaction of the drugs with hydroperoxyl radicals indicated an indirect reaction path owing to the presence of pre- and postreaction complexes. In some cases, the rate constant for the H-abstraction reaction (k = 2.8 × 103 L mol-1 s-1) is found to be close to that of a well-known non-phenolic antioxidant, α-terpinene (k = 4.3 × 103 L mol-1 s-1). Quantification of charge transfer character among the drugs with DNA bases and molecular docking calculations confirmed the groove binding model and predicted the drugs to be safe from DNA damage. A theoretical evaluation of the mechanistic details governing the antioxidant property along with the proven stress reversal ability of these AD drugs provided new insights to design and develop more efficient drugs with dual therapeutic potential.

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.

Deciphering Spectroscopic and Structural Insights into the Photophysical Behavior of 2,2'-Dipyridylamine: An Efficient Environment Sensitive Fluorescence Probe.

Excited state deactivation properties and the effects of solvent hydrogen bonding (HB) on the photophysical behavior of 2,2'-dypyridylamine (DPyA) were investigated by steady state and time-resolved fluorescence experiments, molecular docking, and density functional theory (DFT) calculations. In addition to the polarity effect, the contributions of solvent HB donation (HBD) acidity and HB acceptance (HBA) basicity to modulate the solvatochromic spectral properties were estimated from multiparametric linear regression analysis using Kamlet-Taft (KT) and Catalán formalisms. The importance of C-N bond torsion, leading to the trans → cis conversion, was manifested by substantial increase in DPyA fluorescence yield in the presence of cyclodextrin (CD) and glycerol. The unusually low fluorescence yield in aqueous medium was explained on the basis of synergistic effect of solvent hydrogen bonding combined with excited state conformational isomerization, which renders DPyA to be an excellent environment sensitive fluorescence reporter. The experimental results were verified with structural insights obtained from DFT calculations at B3LYP/6-311++G(d,p) level and construction of potential energy surface (PES) in the ground state as well as in the excited states.

Dietary polyphenols inhibit plasma protein arabinosylation: Biomolecular interaction of genistein and ellagic acid with serum albumins.

The mode of interaction of polyphenolic compounds like genistein (GTN) and ellagic acid (EGA) with human and bovine serum albumin (HSA and BSA, respectively) was found to differ significantly. Stern-Volmer (SV) analysis of the fluorescence quenching data revealed that the binding strength of EGA (1.9 ± 0.09 × 105 M-1) to HSA is about one order of magnitude higher than GTN (2.24 ± 0.06 × 104 M-1). While the static quenching of HSA fluorescence was found to proceed through simple Stern-Volmer (SV) mechanism, a quenching sphere-of-action model was indispensable for BSA. Temperature dependent fluorescence along with a series of other biophysical experiments and ensemble docking calculation revealed that EGA and GTN bind to the serum proteins primarily through the entropy driven process. The α-helical content and the microenvironment near Trp residue of HSA and BSA did not show any appreciable change due to the binding of either GTN or EGA. Interestingly, both GTN and EGA were found to inhibit the formation of advanced glycated end (AGE) product of serum proteins up to the extent of 70-90% within 12-24 h. Relatively moderate binding propensity along with the anti-glycation ability of the polyphenols confirmed that GTN and EGA can be used either as an alternative or towards development of suitable drugs in the prevention of many diabetic-related complications.

Sulfonylurea Class of Antidiabetic Drugs Inhibit Acetylcholinesterase Activity: Unexplored Auxiliary Pharmacological Benefit toward Alzheimer's Disease.

Contemporary literature documents extensive research on common causative mechanisms, pathogenic pathways and dual effective remedies for Alzheimer's disease (AD) and Type 2 diabetes mellitus (T2DM). Tolbutamide (TBM), chlorpropamide (CPM), and glyburide (GLY) are three sulfonylurea antidiabetic drugs of different generations. All these drugs were found to exhibit moderate to strong inhibitory efficiency on the neurotransmitter degrading enzyme acetylcholinesterase (AChE) with GLY (IC50 = 0.74 ± 0.02 µM) being the most potent, followed by CPM (IC50 = 5.72 ± 0.24 µM) and TBM (IC50 = 28.9 ± 1.60 µM). Notably, the inhibition efficiency of GLY is even comparable with the FDA approved AD drug, donepezil (DON). The larger size of GLY spans almost the full gorge of AChE ranging from catalytic active site (CAS) to the peripheral active site (PAS) with relatively strong binding affinity (6.0 × 105 M-1) and acts as a competitive inhibitor for AChE. On the other hand, while they show relatively weak binding ((2-6) × 104 M-1), both CPM and TBM act as noncompetitive binders. While these two drugs can bind to PAS, MD simulation results predict an alternative noncompetitive inhibition mechanism for CPM. These results open the possibility of repurposing the antidiabetic drugs, particularly GLY, in the treatment of AD. The consequential side effect of excess acetylcholine production, due to the administration of these drugs to AD-unaffected patients, can be rectified by using colloidal gold and silver nanofluids as potential AChE activity boosters.

Modulated Protein Binding Ability of Anti-Diabetic Drugs in Presence of Monodispersed Gold Nanoparticles and its Inhibitory Potential towards Advanced Glycated End (AGE) Product Formation.

Binding strength of the anti-diabetic drugs chlorpropamide (CPM) and tolbutamide (TBM) with model protein bovine serum albumin (BSA) shows strong modulation in presence of colloidal gold nanoparticles (AuNP). Intrinsic tryptophan fluorescence of both the native BSA and BSA-AuNP conjugate quenched in presence of the drugs. Stern-Volmer quenching constant (KSV) of CPM binding to BSA-AuNP conjugate at different temperatures is almost twice (6.76~14.76 × 103 M-1) than the corresponding values in native BSA (3.21~5.72 × 103 M-1). However, the calculated KSV values with TBM show certain degree of reduction in presence of AuNP (6.46× 103 M-1), while comparing with native BSA (8.83 × 103 M-1). The binding mode of CPM towards BSA-AuNP conjugate is mainly through hydrophobic forces; whereas, TBM binding is identified to be Van der Waal's and hydrogen bonding type of interaction. Fluorescence lifetime analysis confirms static type of quenching for the intrinsic tryptophan fluorescence of BSA as well as BSA-AuNP conjugate with addition of CPM and TBM at different concentrations. The α-helical content in the secondary structure of BSA is decreased to 48.32% and 45. 28% in presence of AuNP, when the concentration of CPM is 0.08 mM and 0.16 mM in comparison with that of native protein (50.13%). On the other hand, the intensity of sugar induced advanced glycated end (AGE) product fluorescence is decreased by 55% and 80% at 0.13 nM and 0.68 nM AuNP, respectively. Change in the binding strength of the drugs with transport protein and reduced AGE product formation in presence of AuNP could lead to a major development in the field of nanomedicine and associated drug delivery techniques. Graphical Abstract Modulated drug binding ability and AGE product formation of serum proteins in presence of AuNP.

Therapeutic potency of substituted chromones as Alzheimer's drug: Elucidation of acetylcholinesterase inhibitory activity through spectroscopic and molecular modelling investigation.

Introduction: Documentation on the potency of chromones as acetylcholinesterase (AChE) antagonists has paved the way for the design and usage of new chromone analogues as inhibitors of AChE modelled on the hypothesis based on cholinergic pathway of Alzheimer's disease (AD). Here, 2 minimally substituted chromones, namely 3-cyanochromone (CyC) and 7-amino-3- methylchromone (AMC), were checked for their AChE inhibition efficacies and plasma protein modulation. Methods: Colorimetric enzymatic assay as well as fluorescence measurements were performed for obtaining the experimental results, which were further corroborated by molecular docking and simulation studies. Results: The investigated systems exhibited strong inhibition activities against AChE, with CyC (IC50= 85.12 ± 6.70 nM) acting as better inhibitor than AMC (IC50 = 103.09 ± 11.90 nM) and both having IC50 values in the range of FDA approved cholinergic drug Donepezil (IC50 = 74.13 ± 8.30 nM). Non-competitive inhibition was observed in both the cases with the inhibitors binding near the peripheral anionic site (PAS) of the enzyme. Having one planar nitrile group in CyC as compared to sp3 hybridised substituents in AMC facilitated stacking interactions in the former, accounting for its higher inhibitory efficacy. A significant decrease in the inhibition potency of CyC (~32%) was noted in comparison with AMC (~5%) when the experiments were performed in presence of human serum albumin (HSA) instead of pure aqueous buffer. Conclusion: This comparative study affirms the importance of meticulous substitution in the chromone scaffold to promote maximum inhibition potency, while considering their usage as AD drugs.

Interaction of caffeine and sulfadiazine with lysozyme adsorbed at colloidal metal nanoparticle interface: influence on drug transport ability and antibacterial activity.

The modulated bioactivity of proteins immobilized on nanoparticle (NP) interfaces is of tremendous interest toward designing better therapeutic and diagnostic tools. In this work, binding behavior and the antibacterial activity of free lysozyme (LYS) as well as its non-covalent assembly with silver (Ag) and gold (Au) colloidal NPs were compared in presence of two model drugs, viz. sulfadiazine (SDZ) and caffeine (CAF). Intrinsic protein fluorescence was found to quench due to the formation drug-protein complex in case of CAF resulting a linear Stern-Volmer (SV) plot with KSV = 1.83 × 103 M-1.On the other hand, a positive deviation beyond [SDZ] ~0.15 mM is explained due to the formation of a fluorophore - quencher sphere with radius of 13.85 ± 1.80 Å that results almost one order of magnitude higher KSV (1.75 × 104 M-1). Molecular docking calculation also predicts relatively more stabilized complex of SDZ with LYS in comparison to CAF (ΔE ~ 3 kJ mol-1). Synchronous fluorescence results corresponding to Trp and Tyr residues as well as FTIR spectra in the amide I region of LYS confirms minimal deformation in the LYS secondary structure on adsorption to spherical NP surface. Although the nature of LYS-drug interaction remains invariant, the extent of quenching interaction as well as the drug binding ability is strongly modulated in presence of NPs. Further, the antibacterial activity of LYS in presence of the investigated drugs shows 9-14% upsurge with AuNP, in sharp contrast to ca. 31-34% decrease in AgNP.

Novel coumarin derivatives as potent acetylcholinesterase inhibitors: insight into efficacy, mode and site of inhibition.

The inhibitory efficacy of two substituted coumarin derivatives on the activity of neurodegenerative enzyme acetylcholinesterase (AChE) was assessed in aqueous buffer as well as in the presence of human serum albumin (HSA) and compared against standard cholinergic AD drug, Donepezil (DON). The experimental data revealed the inhibition to be of non-competitive type with both the systems showing substantial inhibitory activity on AChE. In fact, one of the tested compounds Chromenyl Coumarate (CC) was found to be better inhibitor (IC50 = 48.49 ± 5.6 nM) than the reference drug DON (IC50 = 74.13 ± 8.3 nM), unequivocally amplifying its importance. The structure of the compound was found to play a vital role in the inhibitory efficiency, validating previous Structure Activity Relationship (SAR) reviews for coumarin. The mechanism of inhibition remained impervious when the experimental medium was switched from aqueous buffer to HSA, albeit noticeable change in the inhibition potency of the compound 3, 3'- Methylene-bis (4-hydroxy coumarin) (MHC) (38%) and CC (35%). Both the coumarin derivatives were observed to bind to the peripheral anionic site (PAS) of AChE and also found to displace the fluorescence marker thioflavinT (ThT) from AChE binding pocket. All experimental observations were seconded by molecular docking and MD simulation results. The inferences drawn in this study form a foundation for further investigation on these compounds; magnifying the probability of their usage as AD drugs and re-emphasizes the significance of drug delivery media while considering the inhibition potencies of targeted drugs.

Interaction of chlorpropamide with serum albumin: Effect on advanced glycated end (AGE) product fluorescence.

Carrier proteins like bovine or human serum albumin (BSA and HSA, respectively) are prone to glycation as compared to the other available proteins. In this study, reducing sugars such as l-arabinose (ara), d-(-) galactose (gal) and d-(-) fructose (fru) were used to create model glycated serum albumins and binding ability of these with well-known antidiabetic drug chlorpropamide (CPM) was monitored. Fluorescence quenching experiment revealed that interaction of CPM with native as well as glycated albumins undergoes through a ground state complex formation. CPM binds strongly to glycated HSA with arabinose (gHSAara) as compared to other glycated systems and to the native proteins. CPM interacts through Van der Waals and hydrogen bonding interaction to glycated BSA by d-(-) fructose (gBSAfru) and also with native HSA; whereas, it's interaction with BSA and others glycated systems like gBSAara, gBSAgal and gHSAara occurs primarily through hydrophobic interaction. CPM showed an enhancement in the production of the advanced glycated end products (AGE) in all the glycated proteins. The difference in the binding capability of CPM to differently glycated albumins could be a major model to understand the drug carrying capacity of the glycated serum albumins.

Quenching of Luminol Fluorescence at Nano-Bio Interface: Towards the Development of an Efficient Energy Transfer System.

Surface modified colloidal gold (Au) and silver (Ag) nanoparticles (NPs) were used as efficient quenchers of luminol (LH2) fluorescence either in homogeneous aqueous medium or its noncovalent assembly with bovine serum albumin (BSA). The mechanism as well as the extent of fluorescence quenching was found to be strongly dependent on the nature of the nanoparticles. While simple static type fluorescence quenching mechanism was perceived with AuNP, a more complex protocol involving quenching sphere model was envisaged for AgNP quenching. Nevertheless, the magnitude of Stern-Volmer (SV) quenching constant (KSV ~ 108-1010 M-1) was calculated to be ca. 104 times more for surface quoted NPs in comparison with BSA-NP bioconjugates system. On the other hand, a highly efficient (E ≈ 95%) energy transfer (ET) process was predicted for LH2 captured in the hydrophobic assembly with BSA in presence of AgNP as an acceptor. The ET efficiency is critically dependent on the concentration of BSA and nicely correlated with the extent of NP surface coverage. However, fluorescence quenching on AuNP surface is relatively less responsive towards protein concentration, primarily due to the difference in surface activity as well as the mode of interaction of the protein with NPs. Graphical Abstract Energy transfer from excited luminol to metal nanoparticles is strongly modulated in presence of serum albumins.

An efficient synthesis of triazolium ion based NHC precursors using diaryliodonium salts and their photophysical properties.

Copper-catalysed N-arylation of fused triazoles using diaryliodonium salts as an aryl source is described. This scalable protocol displayed good compatibility towards diverse sensitive functional groups like ester, alkyl and nitro groups and halogens (F, Cl, Br). The synthetic usefulness of the prepared triazolium salts was proved by preparing α-hydroxyketone through benzoin condensation. Photophysical studies of these compounds showed promising Stokes-shifted fluorescence emission in aqueous medium, so this molecular framework could be a proficient probe for biological applications.

Correlation of cholinergic drug induced quenching of acetylcholinesterase bound thioflavin-T fluorescence with their inhibition activity.

The development of new acetylcholinesterase inhibitors (AChEIs) and subsequent assay of their inhibition efficiency is considered to be a key step for AD treatment. The fluorescence intensity of thioflavin-T (ThT) bound in the active site of acetylcholinesterase (AChE) quenches substantially in presence of standard AChEI drugs due to the dynamic replacement of the fluorophore from the AChE active site as confirmed from steady state emission as well as time-resolved fluorescence anisotropy measurement and molecular dynamics simulation in conjunction with docking calculation. The parametrized % quenching data for individual system shows excellent correlation with enzyme inhibition activity measured independently by standard Ellman AChE assay method in a high throughput plate reader system. The results are encouraging towards design of a fluorescence intensity based AChE inhibition assay method and may provide a better toolset to rapidly evaluate as well as develop newer AChE-inhibitors for AD treatment.

Identification of molecular descriptors for design of novel Isoalloxazine derivatives as potential Acetylcholinesterase inhibitors against Alzheimer's disease.

In Alzheimer's disease (AD), the level of Acetylcholine (ACh) neurotransmitter is reduced. Since Acetylcholinesterase (AChE) cleaves ACh, inhibitors of AChE are very much sought after for AD treatment. The side effects of current inhibitors necessitate development of newer AChE inhibitors. Isoalloxazine derivatives have proved to be promising (AChE) inhibitors. However, their structure-activity relationship studies have not been reported till date. In the present work, various quantitative structure-activity relationship (QSAR) building methods such as multiple linear regression (MLR), partial least squares ,and principal component regression were employed to derive 3D-QSAR models using steric and electrostatic field descriptors. Statistically significant model was obtained using MLR coupled with stepwise selection method having r2 = .9405, cross validated r2 (q2) = .6683, and a high predictability (pred_r2 = .6206 and standard error, pred_r2se = .2491). Steric and electrostatic contribution plot revealed three electrostatic fields E_496, E_386 and E_577 and one steric field S_60 contributing towards biological activity. A ligand-based 3D-pharmacophore model was generated consisting of eight pharmacophore features. Isoalloxazine derivatives were docked against human AChE, which revealed critical residues implicated in hydrogen bonds as well as hydrophobic interactions. The binding modes of docked complexes (AChE_IA1 and AChE_IA14) were validated by molecular dynamics simulation which showed their stable trajectories in terms of root mean square deviation and molecular mechanics/Poisson-Boltzmann surface area binding free energy analysis revealed key residues contributing significantly to overall binding energy. The present study may be useful in the design of more potent Isoalloxazine derivatives as AChE inhibitors.