A comprehensive computational study to explore promising natural bioactive compounds targeting glycosyltransferase MurG in Escherichia coli for potential drug development.

Peptidoglycan is a carbohydrate with a cross-linked structure that protects the cytoplasmic membrane of bacterial cells from damage. The mechanism of peptidoglycan biosynthesis involves the main synthesizing enzyme glycosyltransferase MurG, which is known as a potential target for antibiotic therapy. Many MurG inhibitors have been recognized as MurG targets, but high toxicity and drug-resistant Escherichia coli strains remain the most important problems for further development. In addition, the discovery of selective MurG inhibitors has been limited to the synthesis of peptidoglycan-mimicking compounds. The present study employed drug discovery, such as virtual screening using molecular docking, drug likeness ADMET proprieties predictions, and molecular dynamics (MD) simulation, to identify potential natural products (NPs) for Escherichia coli. We conducted a screening of 30,926 NPs from the NPASS database. Subsequently, 20 of these compounds successfully passed the potency, pharmacokinetic, ADMET screening assays, and their validation was further confirmed through molecular docking. The best three hits and the standard were chosen for further MD simulations up to 400 ns and energy calculations to investigate the stability of the NPs-MurG complexes. The analyses of MD simulations and total binding energies suggested the higher stability of NPC272174. The potential compounds can be further explored in vivo and in vitro for promising novel antibacterial drug discovery.

Identification of Potent Acetylcholinesterase Inhibitors as New Candidates for Alzheimer Disease via Virtual Screening, Molecular Docking, Dynamic Simulation, and Molecular Mechanics-Poisson-Boltzmann Surface Area Calculations.

Huperzine A (HUP) plays a crucial role in Alzheimer's therapy by enhancing cognitive function through increased cholinergic activity as a reversible acetylcholinesterase (AChE) inhibitor. Despite some limitations being seen in AChE inhibitors, ongoing research remains dedicated to finding innovative and more effective treatments for Alzheimer's disease. To achieve the goal of the discovery of potential HUP analogues with improved physicochemical properties, less toxic properties, and high biological activity, many in silico methods were applied. Based on the acetylcholinesterase-ligand complex, an e-pharmacophore model was developed. Subsequently, a virtual screening involving a collection of 1762 natural compounds, sourced from the PubChem database, was performed. This screening yielded 131 compounds that exhibited compatibility with the established pharmacophoric hypothesis. These selected ligands were then subjected to molecular docking within the active site of the 4EY5 receptor. As a result, we identified four compounds that displayed remarkable docking scores and exhibited low free binding energy to the target. These top four compounds, CID_162895946, CID_44461278, CID_44285285, and CID_81108419, were submitted to ADMET prediction and molecular dynamic simulations, yielding encouraging findings in terms of their pharmacokinetic characteristics and stability. Finally, the molecular dynamic simulation, cross-dynamic correlation matrix, free energy landscape, and MM-PBSA calculations demonstrated that two ligands from the selected ligands formed very resilient complexes with the enzyme acetylcholinesterase, with significant binding affinity. Therefore, these two compounds are recommended for further experimental research as possible (AChE) inhibitors.

Computer-Aided Strategy on 5-(Substituted benzylidene) Thiazolidine-2,4-Diones to Develop New and Potent PTP1B Inhibitors: QSAR Modeling, Molecular Docking, Molecular Dynamics, PASS Predictions, and DFT Investigations.

A set of 5-(substituted benzylidene) thiazolidine-2,4-dione derivatives was explored to study the main structural requirement for the design of protein tyrosine phosphatase 1B (PTP1B) inhibitors. Utilizing multiple linear regression (MLR) analysis, we constructed a robust quantitative structure-activity relationship (QSAR) model to predict inhibitory activity, resulting in a noteworthy correlation coefficient (R2) of 0.942. Rigorous cross-validation using the leave-one-out (LOO) technique and statistical parameter calculations affirmed the model's reliability, with the QSAR analysis revealing 10 distinct structural patterns influencing PTP1B inhibitory activity. Compound 7e(ref) emerged as the optimal scaffold for drug design. Seven new PTP1B inhibitors were designed based on the QSAR model, followed by molecular docking studies to predict interactions and identify structural features. Pharmacokinetics properties were assessed through drug-likeness and ADMET studies. After that density functional theory (DFT) was conducted to assess the stability and reactivity of potential diabetes mellitus drug candidates. The subsequent dynamic simulation phase provided additional insights into stability and interactions dynamics of the top-ranked compound 11c. This comprehensive approach enhances our understanding of potential drug candidates for treating diabetes mellitus.

Integrative Approach for Designing Novel Triazole Derivatives as α-Glucosidase Inhibitors: QSAR, Molecular Docking, ADMET, and Molecular Dynamics Investigations.

In response to the increasing prevalence of diabetes mellitus and the limitations associated with the current treatments, there is a growing need to develop novel medications for this disease. This study is focused on creating new compounds that exhibit a strong inhibition of alpha-glucosidase, which is a pivotal enzyme in diabetes control. A set of 33 triazole derivatives underwent an extensive QSAR analysis, aiming to identify the key factors influencing their inhibitory activity against α-glucosidase. Using the multiple linear regression (MLR) model, seven promising compounds were designed as potential drugs. Molecular docking and dynamics simulations were employed to shed light on the mode of interaction between the ligands and the target, and the stability of the obtained complexes. Furthermore, the pharmacokinetic properties of the designed compounds were assessed to predict their behavior in the human body. The binding free energy was also calculated using MMGBSA method and revealed favorable thermodynamic properties. The results highlighted three novel compounds with high biological activity, strong binding affinity to the target enzyme, and suitability for oral administration. These results offer interesting prospects for the development of effective and well-tolerated medications against diabetes mellitus.

Ligand-Based Design of Novel Quinoline Derivatives as Potential Anticancer Agents: An In-Silico Virtual Screening Approach.

In this study, using the Comparative Molecular Field Analysis (CoMFA) approach, the structure-activity relationship of 33 small quinoline-based compounds with biological anti-gastric cancer activity in vitro was analyzed in 3D space. Once the 3D geometric and energy structure of the target chemical library has been optimized and their steric and electrostatic molecular field descriptions computed, the ideal 3D-QSAR model is generated and matched using the Partial Least Squares regression (PLS) algorithm. The accuracy, statistical precision, and predictive power of the developed 3D-QSAR model were confirmed by a range of internal and external validations, which were interpreted by robust correlation coefficients (RTrain2=0.931; Qcv2=0.625; RTest2=0.875). After carefully analyzing the contour maps produced by the trained 3D-QSAR model, it was discovered that certain structural characteristics are beneficial for enhancing the anti-gastric cancer properties of Quinoline derivatives. Based on this information, a total of five new quinoline compounds were developed, with their biological activity improved and their drug-like bioavailability measured using POM calculations. To further explore the potential of these compounds, molecular docking and molecular dynamics simulations were performed in an aqueous environment for 100 nanoseconds, specifically targeting serine/threonine protein kinase. Overall, the new findings of this study can serve as a starting point for further experiments with a view to the identification and design of a potential next-generation drug for target therapy against cancer.

Novel Grafted Hydrogel for Iron and Ammonia Removal from Groundwater: A Synthesis and Computational Chemistry Study.

Current research is moving towards iron and ammonia elimination from groundwater. Here, we are using a poly acrylic-poly acrylamide hydrogel that is grafted with 3-chloroaniline. This copolymer was synthesized by addition polymerization technique. The effects of agitation time, dosage and adsorbent temperature on the removal process sensitivity were investigated. The copolymer was described experientially and theoretically. Isothermal kinetic adsorption models are discussed. This hydrogel could be regenerated efficiently (98.3% removal of iron and 100% removal of ammonia). The density functional theory (DFT) method, using B3LYP/6-311G(d,p), and the LANL2DZ level of the theory were managed to investigate the stationary states of the grafted copolymer and the complexation energy of the hydrogel with the studied cations. DFT has been used to investigate the Natural Bond Orbital (NBO) properties to locate the most negative centers on the hydrogel. The calculated complexation energy showed hydrogel selectivity with regard to the studied cations.

First Exclusive Stereo- and Regioselective Preparation of 5-Arylimino-1,3,4-Selenadiazole Derivatives: Synthesis, NMR analysis, and Computational Studies.

Isoselenocyanates are valuable coupling partners required for preparing key chemical intermediates and biologically active molecules in an accelerated and effective way. Likewise, (Z)-2-oxo-N-phenylpropanehydrazonoyl chlorides have been employed in numerous one-step heteroannulation reactions to assemble the structural core of several various kinds of heterocyclic compounds. Here, we describe the inverse electron demand 1,3-dipolar cycloaddition reaction of isoselenocyanates with a variety of substituted (Z)-2-oxo-N-phenylpropanehydrazonoyl chlorides to generate, regioselectively and stereoselectively, a series of 5-arylimino-1,3,4-selenadiazole derivatives comprising a multitude of functional groups on both aryl rings. The synthetic method features gentle room-temperature conditions, wide substrate scope, and good to high reaction yields. The selenadiazoles were separated by gravity filtration in all instances and chemical structures were validated by multinuclear NMR spectroscopy and high accuracy mass spectral measurements. First conclusive molecular structure elucidation of the observed 5-arylimino-selenadiazole regioisomer was verified by single-crystal X-ray diffraction analysis. Crystal-structure measurement was successfully carried out on (Z)-1-(4-(4-iodophenyl)-5-(p-tolylimino)-4,5-dihydro-1,3,4-selenadiazol-2-yl)ethan-1-one and (Z)-1-(5-((4-methoxyphenyl)imino)-4-(4-(methylthio)phenyl)-4,5-dihydro-1,3,4-selenadiazol-2-yl)ethan-1-one. Likewise, the (Z)-geometry of the hydrazonoyl chloride reactant was proven by X-ray diffraction studies. As representative examples, crystal-structure determination was carried out on (Z)-2-oxo-N-phenylpropanehydrazonoyl chloride and (Z)-N-(3,5-bis(trifluoromethyl)phenyl)-2-oxopropanehydrazonoyl chloride. Density functional theory calculations at the B3LYP-D4/def2-TZVP level were conducted to support the noted experimental findings and suggested mechanism.

QuinoxalineTacrine QT78, a Cholinesterase Inhibitor as a Potential Ligand for Alzheimer's Disease Therapy.

We report the synthesis and relevant pharmacological properties of the quinoxalinetacrine (QT) hybrid QT78 in a project targeted to identify new non-hepatotoxic tacrine derivatives for Alzheimer's disease therapy. We have found that QT78 is less toxic than tacrine at high concentrations (from 100 µM to 1 mM), less potent than tacrine as a ChE inhibitor, but shows selective BuChE inhibition (IC50 (hAChE) = 22.0 ± 1.3 µM; IC50 (hBuChE) = 6.79 ± 0.33 µM). Moreover, QT78 showed effective and strong neuroprotection against diverse toxic stimuli, such as rotenone plus oligomycin-A or okadaic acid, of biological significance for Alzheimer's disease.

The Reaction of Thiyl Radical with Methyl Linoleate: Completing the Picture.

Cis lipids can be converted by thiols and free radicals into trans lipids, which are therefore a valuable tell-tale for free radical activity in the cell's lipidome. Our previous studies have shown that polyunsaturated lipids are isomerized by alkanethiyl radicals (S•) in a cycle propagated by reversible double-bond addition and terminated by radical H-abstraction from the lipid. A critical flaw in this picture has long been that the reported lipid abstraction rate from radiolysis studies is faster than addition-isomerization, implying that the "cycle" must be terminating faster than it is propagating! Herein, we resolved this longstanding puzzle by combining a detailed product analysis, with reinvestigation of the time-resolved kinetics, DFT calculations of the indicated pathways, and reformulation of the radical-stasis equations. We have determined thiol-coupled products in dilute solutions arise mainly from addition to the inside position of the bisallylic group, followed by rapid intramolecular H• transfer, yielding allylic radicals (LZZ + S• ⇄ SL• → SL'•) that are slowly reduced by thiol (SL'• + SH → SL'H + S•). The first-order grow-in rate of the L-H• signal (kexp280nm) may therefore be dominated by the addition-H-translocation rather than slower direct H•-abstraction. Steady-state kinetic analysis of the new mechanism is consistent with products and the rates and trends for polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs), and mixtures, with and without physiological [O2]. Implications of this new paradigm for the thiol-ene reactivity fall in an interdisciplinary research area spanning from synthetic applications to metabolomics.

The proof-of-concept of ASS234: Peripherally administered ASS234 enters the central nervous system and reduces pathology in a male mouse model of Alzheimer disease.

BACKGROUND: The heterogeneity of Alzheimer disease requires the development of multitarget drugs for treating the symptoms of the disease and its progression. Both cholinergic and monoamine oxidase dysfunctions are involved in the pathological process. Thus, we hypothesized that the development of therapies focused on these targets might be effective. We have developed and assessed a new product, coded ASS234, a multipotent acetyl and butyrylcholinesterase/monoamine oxidase A-B inhibitor with a potent inhibitory effect on amyloid-ß aggregation as well as antioxidant and antiapoptotic properties. But there is a need to reliably correlate in vitro and in vivo drug release data. METHODS: We examined the effect of ASS234 on cognition in healthy adult C57BL/6J mice in a model of scopolamine-induced cognitive impairment that often accompanies normal and pathological aging. Also, in a characterized transgenic APPswe/PS1ΔE9 mouse model of Alzheimer disease, we examined the effects of short-term ASS234 treatment on plaque deposition and gliosis using immunohistochemistry. Toxicology of ASS234 was assessed using a quantitative high-throughput in vitro cytotoxicity screening assay following the MTT assay method in HepG2 liver cells. RESULTS: In vivo, ASS234 significantly decreased scopolamine-induced learning deficits in C57BL/6J mice. Also, reduction of amyloid plaque burden and gliosis in the cortex and hippocampus was assessed. In vitro, ASS234 exhibited lesser toxicity than donepezil and tacrine. LIMITATIONS: The study was conducted in male mice only. Although the Alzheimer disease model does not recapitulate all features of the human disease, it exhibits progressive monoaminergic neurodegeneration. CONCLUSION: ASS234 is a promising alternative drug of choice to treat the cognitive decline and neurodegeneration underlying Alzheimer disease.

N-Benzylpiperidine Derivatives as α7 Nicotinic Receptor Antagonists.

A series of multitarget directed propargylamines, as well as other differently susbstituted piperidines have been screened as potential modulators of neuronal nicotinic acetylcholine receptors (nAChRs). Most of them showed antagonist actions on α7 nAChRs. Especially, compounds 13, 26, and 38 displayed submicromolar IC50 values on homomeric α7 nAChRs, whereas they were less effective on heteromeric α3ß4 and α4ß2 nAChRs (up to 20-fold higher IC50 values in the case of 13). Antagonism was concentration dependent and noncompetitive, suggesting that these compounds behave as negative allosteric modulators of nAChRs. Upon the study of a series of less complex derivatives, the N-benzylpiperidine motif, common to these compounds, was found to be the main pharmacophoric group. Thus, 2-(1-benzylpiperidin-4-yl)-ethylamine (48) showed an inhibitory potency comparable to the one of the previous compounds and also a clear preference for α7 nAChRs. In a neuroblastoma cell line, representative compounds 13 and 48 also inhibited, in a concentration-dependent manner, cytosolic Ca(2+) signals mediated by nAChRs. Finally, compounds 38 and 13 inhibited 5-HT3A serotonin receptors whereas they had no effect on α1 glycine receptors. Given the multifactorial nature of many pathologies in which nAChRs are involved, these piperidine antagonists could have a therapeutic potential in cases where cholinergic activity has to be negatively modulated.

The reaction of 2-amino-4H-pyrans with N-bromosuccinimide.

The reaction of racemic 2-amino-4H-pyrans, such as 3-amino-1-aryl-1H-benzo[f]chromene-2-carbonitriles, with N-bromosuccinimide (NBS), in CH2Cl2, at room temperature, is a very quick, regio, stereoselective, and high yielding process, affording major racemic (1S, 2S)-2-bromo-3-imino-benzo[f]chromene or racemic (1S, 2S)-2-bromo-3-(bromoimino)-benzo[f]chromene derivatives, when using 1.0 or 2.2 equivalents of NBS, respectively. This reaction, extended to isomeric 2-amino-4-aryl-4H-benzo[h]chromene-3-carbonitriles, showed an unexpected reactivity, affording racemic (3S,4S)-3-bromo-2-(bromoimino)-benzo[h]chromene-3-carbonitriles or 2-oxo-2H-benzo[h]chromene-3-carbonitriles, when using 2.2 or 1.0 equivalents of NBS, respectively. The reaction of alkyl 6-amino-5-cyano-2-methyl-4H-pyran-3-carboxylates has yielded unstable racemic (3S,4S)-alkyl 3-bromo-2-(bromoimino)-3-cyano-6-methyl-3,4-dihydro-2H-pyran-5-carboxylates. The mechanism of these reactions has been investigated by computational methods.

Multipotent cholinesterase/monoamine oxidase inhibitors for the treatment of Alzheimer's disease: design, synthesis, biochemical evaluation, ADMET, molecular modeling, and QSAR analysis of novel donepezil-pyridyl hybrids.

The design, synthesis, and biochemical evaluation of donepezil-pyridyl hybrids (DPHs) as multipotent cholinesterase (ChE) and monoamine oxidase (MAO) inhibitors for the potential treatment of Alzheimer's disease (AD) is reported. The 3D-quantitative structure-activity relationship study was used to define 3D-pharmacophores for inhibition of MAO A/B, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) enzymes and to design DPHs as novel multi-target drug candidates with potential impact in the therapy of AD. DPH14 (Electrophorus electricus AChE [EeAChE]: half maximal inhibitory concentration [IC50] =1.1±0.3 nM; equine butyrylcholinesterase [eqBuChE]: IC50 =600±80 nM) was 318-fold more potent for the inhibition of AChE, and 1.3-fold less potent for the inhibition of BuChE than the reference compound ASS234. DPH14 is a potent human recombinant BuChE (hBuChE) inhibitor, in the same range as DPH12 or DPH16, but 13.1-fold less potent than DPH15 for the inhibition of human recombinant AChE (hAChE). Compared with donepezil, DPH14 is almost equipotent for the inhibition of hAChE, and 8.8-fold more potent for hBuChE. Concerning human monoamine oxidase (hMAO) A inhibition, only DPH9 and 5 proved active, compound DPH9 being the most potent (IC50 [MAO A] =5,700±2,100 nM). For hMAO B, only DPHs 13 and 14 were moderate inhibitors, and compound DPH14 was the most potent (IC50 [MAO B] =3,950±940 nM). Molecular modeling of inhibitor DPH14 within EeAChE showed a binding mode with an extended conformation, interacting simultaneously with both catalytic and peripheral sites of EeAChE thanks to a linker of appropriate length. Absortion, distribution, metabolism, excretion and toxicity analysis showed that structures lacking phenyl-substituent show better druglikeness profiles; in particular, DPHs13-15 showed the most suitable absortion, distribution, metabolism, excretion and toxicity properties. Novel donepezil-pyridyl hybrid DPH14 is a potent, moderately selective hAChE and selective irreversible hMAO B inhibitor which might be considered as a promising compound for further development for the treatment of AD.

N-Methyl-N-((1-methyl-5-(3-(1-(2-methylbenzyl)piperidin-4-yl)propoxy)-1H-indol-2-yl)methyl)prop-2-yn-1-amine, a new cholinesterase and monoamine oxidase dual inhibitor.

On the basis of N-((5-(3-(1-benzylpiperidin-4-yl)propoxy)-1-methyl-1H-indol-2-yl)methyl)-N-methylprop-2-yn-1-amine (II, ASS234) and QSAR predictions, in this work we have designed, synthesized, and evaluated a number of new indole derivatives from which we have identified N-methyl-N-((1-methyl-5-(3-(1-(2-methylbenzyl)piperidin-4-yl)propoxy)-1H-indol-2-yl)methyl)prop-2-yn-1-amine (2, MBA236) as a new cholinesterase and monoamine oxidase dual inhibitor.

Donepezil + propargylamine + 8-hydroxyquinoline hybrids as new multifunctional metal-chelators, ChE and MAO inhibitors for the potential treatment of Alzheimer's disease.

The synthesis, biochemical evaluation, ADMET, toxicity and molecular modeling of novel multi-target-directed Donepezil + Propargylamine + 8-Hydroxyquinoline (DPH) hybrids 1-7 for the potential prevention and treatment of Alzheimer's disease is described. The most interesting derivative was racemic α-aminotrile4-(1-benzylpiperidin-4-yl)-2-(((8-hydroxyquinolin-5-yl)methyl)(prop-2-yn-1-yl)amino) butanenitrile (DPH6) [MAO A (IC50 = 6.2 ± 0.7 µM; MAO B (IC50 = 10.2 ± 0.9 µM); AChE (IC50 = 1.8 ± 0.1 µM); BuChE (IC50 = 1.6 ± 0.25 µM)], an irreversible MAO A/B inhibitor and mixed-type AChE inhibitor with metal-chelating properties. According to docking studies, both DPH6 enantiomers interact simultaneously with the catalytic and peripheral site of EeAChE through a linker of appropriate length, supporting the observed mixed-type AChE inhibition. Both enantiomers exhibited a relatively similar position of both hydroxyquinoline and benzyl moieties with the rest of the molecule easily accommodated in the relatively large cavity of MAO A. For MAO B, the quinoline system was hosted at the cavity entrance whereas for MAO A this system occupied the substrate cavity. In this disposition the quinoline moiety interacted directly with the FAD aromatic ring. Very similar binding affinity values were also observed for both enantiomers with ChE and MAO enzymes. DPH derivatives exhibited moderate to good ADMET properties and brain penetration capacity for CNS activity. DPH6 was less toxic than donepezil at high concentrations; while at low concentrations both displayed a similar cell viability profile. Finally, in a passive avoidance task, the antiamnesic effect of DPH6 was tested on mice with experimentally induced amnesia. DPH6 was capable to significantly decrease scopolamine-induced learning deficits in healthy adult mice.

Kinetic and structural analysis of the irreversible inhibition of human monoamine oxidases by ASS234, a multi-target compound designed for use in Alzheimer's disease.

Monoamine oxidases (MAO) and cholinesterases are validated targets in the design of drugs for the treatment of Alzheimer's disease. The multi-target compound N-((5-(3-(1-benzylpiperidin-4-yl)propoxy)-1-methyl-1H-indol-2-yl)methyl)-N-methylprop-2-yn-1-amine (ASS234), bearing the MAO-inhibiting propargyl group attached to a donepezil moiety that inhibits cholinesterases, retained activity against human acetyl- and butyryl-cholinesterases. The inhibition of MAO A and MAO B by ASS234 was characterized and compared to other known MAO inhibitors. ASS234 was almost as effective as clorgyline (kinact/KI=3×10(6) min(-1)M(-1)) and was shown by structural studies to form the same N5 covalent adduct with the FAD cofactor.

Design, synthesis, pharmacological evaluation, QSAR analysis, molecular modeling and ADMET of novel donepezil-indolyl hybrids as multipotent cholinesterase/monoamine oxidase inhibitors for the potential treatment of Alzheimer's disease.

The design, synthesis, and pharmacological evaluation of donepezil-indolyl based amines 7-10, amides 12-16, and carboxylic acid derivatives 5 and 11, as multipotent ASS234 analogs, able to inhibit simultaneously cholinesterase (ChE) and monoamine oxidase (MAO) enzymes for the potential treatment of Alzheimer's disease (AD), is reported. Theoretical studies using 3D-Quantitative Structure-Activity Relationship (3D-QSAR) was used to define 3D-pharmacophores for inhibition of MAO A/B, AChE, and BuChE enzymes. We found that, in general, and for the same substituent, amines are more potent ChE inhibitors (see compounds 12, 13 versus 7 and 8) or equipotent (see compounds 14, 15 versus 9 and 10) than the corresponding amides, showing a clear EeAChE inhibition selectivity. For the MAO inhibition, amides were not active, and among the amines, compound 14 was totally MAO A selective, while amines 15 and 16 were quite MAO A selective. Carboxylic acid derivatives 5 and 11 showed a multipotent moderate selective profile as EeACE and MAO A inhibitors. Propargylamine 15 [N-((5-(3-(1-benzylpiperidin-4-yl)propoxy)-1-methyl-1H-indol-2-yl)methyl)prop-2-yn-1-amine] resulted in the most potent hMAO A (IC50 = 5.5 ± 1.4 nM) and moderately potent hMAO B (IC50 = 150 ± 31 nM), EeAChE (IC50 = 190 ± 10 nM), and eqBuChE (IC50 = 830 ± 160 nM) inhibitor. However, the analogous N-allyl and the N-morpholine derivatives 16 and 14 deserve also attention as they show an attractive multipotent profile. To sum up, donepezil-indolyl hybrid 15 is a promising drug for further development for the potential prevention and treatment of AD.

Toxicological and pharmacological evaluation, antioxidant, ADMET and molecular modeling of selected racemic chromenotacrines {11-amino-12-aryl-8,9,10,12-tetrahydro-7H-chromeno[2,3-b]quinolin-3-ols} for the potential prevention and treatment of Alzheimer's disease.

The pharmacological analysis of racemic chromenotacrines (CT) 1-7, bearing the 11-amino-12-aryl-8,9,10,12-tetrahydro-7H-chromeno[2,3-b]quinolin-3-ol ring skeleton, in a series of experiments targeted to explore their potential use for the treatment of Alzheimer's disease (AD), is reported. The toxicological evaluation showed that among all these chromenotacrines, CT6 is much less hepatotoxic than tacrine in a range of concentrations from 1 to 300 µM, measured as cell viability in HepG2 cells. Moreover, CT6 did not significantly increase lactate dehydrogenase, aspartate transaminase, and alanine transaminase release in HepG2 cells. Besides, CT6 treatment exerts a high protective effect against the lipid peroxidation induced after H2O2-treated SH-SY5Y cells, in a concentration-dependent manner. CT6 showed an excellent antioxidant profile in the AAPH test, and protects against the decrease in cell viability induced by respiratory chain inhibitors (Oligomicyn A/Rotenone) and NO donors in neuronal cultures. This effect could be due to a mixed antiapoptotic and antinecrotic neuroprotective effect at low and intermediate CT6 concentrations, respectively. CT1-7 are potent and selective inhibitors of EeAChE in the submicromolar range. CT3 [IC50 (EeAChE) = 0.007 ± 0.003 µM], and CT6 [IC50 (EeAChE) = 0.041 ± 0.001 µM] are the most potent AChE inhibitors. Kinetic studies on the non-toxic chromenotacrine CT6 showed that this compound behaves as a non-competitive inhibitor (Ki = 0.047 ± 0.003 µM), indicating that CT6 binds at the peripheral anionic site, a fact confirmed by molecular modeling analysis. In silico ADMET analysis showed also that CT6 should have a moderate BBB permeability. Consequently, non-toxic chromenotacrine CT6 can be considered as an attractive multipotent molecule for the potential treatment of AD.

Effects of novel monoamine oxidases and cholinesterases targeting compounds on brain neurotransmitters and behavior in rat model of vascular dementia.

Neurodegenerative disorders are associated with different neurochemical and morphological alterations in the brain leading to cognitive and behavioural impairments. New therapeutic strategies comprise multifunctional drugs. The aim of the presented studies is to evaluate in vivo the novel compounds - ASS188 and ASS234 - which combine the benzylpiperidine moiety of the acetylcholinesteras (AChE) inhibitor donepezil and the indolyl propargylamino moiety of the monoaminooxidase (MAO) inhibitor, N-[(5-benzyloxy-1- methyl-1H-indol-2-yl)methyl]-N-methylprop-2-yn-1-amine, with respect to their influence on cerebral amine neurotransmitters systems and neuroprotective activity. The presumed therapeutic potential of these compounds has been evaluated following their administration to rats with experimental vascular dementia. A rat model of the permanent bilateral occlusion of the common carotid arteries (BCCAO) and the holeboard memory test were employed for this purpose. Wistar rats were used, either intact or 1 day after BCCAO. ASS188 (1 mg/kg) and ASS234 (5 mg/kg) were given s.c. for 5 consecutive days. Working and reference memory in rats was evaluated by holeboard tests before- and 7 and 12 days after BCCAO. The activities of MAOs, AChE and histamine N-methyltransferase (HMT), as well as cerebral amines concentrations were assayed. A significant inhibition of brain MAO A (>95%) and weaker MAO B (ca 60%) and HMT (<30%) and reduced AChE activities were recorded with a pronounced (2 - 10 fold) increase in the cerebral concentrations of serotonin, dopamine, and noradrenaline and smaller rises (up to 30%) of histamine. The BCCAO rats treated with ASS188 or ASS234 tended to perform holeboard tests better than the BCCAO untreated group, indicating a beneficial effect of the administered therapeutics.

Multipotent, permeable drug ASS234 inhibits Aß aggregation, possesses antioxidant properties and protects from Aß-induced apoptosis in vitro.

Amyloid beta (Aß) aggregation and deposition is a key pathological hallmark of AD. Growing evidence suggests that neurotoxicity of this peptide is related to the formation of toxic oligomeric aggregates. Therefore, a deeply investigated therapeutic strategy comes at present from blocking the formation of these species to non-toxic aggregates. Among other considered strategies, the multi-target approach has been proposed as a more suitable potential therapy, precisely due to the multifactorial nature of AD. In this context, we recently identified ASS234, a novel compound that possesses a significant multipotent profile since it is able to inhibit cholinesterase and monoamine oxidase enzymes as well as to interfere in Aß aggregation process. In this work, we investigated more in detail the effects of ASS234 on Aß aggregation and toxicity in vitro as well as we explored its ability to penetrate to the CNS. We report that ASS234 inhibited Aß1-42 self-aggregation more efficiently than that of Aß1-40, limiting the formation of fibrillar and oligomeric species. Additionally, ASS234 completely blocked the aggregation mediated by AChE of both Aß1-42 and Aß1-40, showing a dual binding site to AChE. Interestingly, ASS234 significantly reduced Aß1-42-mediated toxicity in SH-SY5Y human neuroblastoma cells through the prevention of the mitochondrial apoptosis pathway activation. Also importantly, we observed a significant ability of ASS234 to capture free-radical species in vitro as well as a potent effect in preventing the Aß1-42-induced depletion of antioxidant enzymes (catalase and SOD-1). Finally, we report the capability of ASS234 to cross the bloodbrain barrier. Overall, our in vitro results show that ASS234 may have an impact on different processes involved in AD pathogenesis and provide evidences that it has encouraging attributes as a therapeutic lead compound.