New cyclopentaquinoline and 3,5-dichlorobenzoic acid hybrids with neuroprotection against oxidative stress for the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative brain disease. Thus, drugs including donepezil, rivastigmine, and galantamine are not entirely effective in the treatment of this multifactorial disease. The present study evaluates eight derivatives (3a-3h) as candidates with stronger anti-AD potential but with less side effects. Reactive oxygen species (ROS) assays were used to assess oxidative stress which involve in the neurodegeneration. The neuroprotective properties of 3e against oxidative stress were done in three experiments using MTT test. The anti-AD potential was determined based on their anticholinesterase inhibition ability, determined using Ellman's method, Aß aggregation potential according to thioflavin (Th) fluorescence assay, and their antioxidative and anti-inflammatory activities. Compound 3e exhibited moderate cholinesterase inhibition activity (AChE, IC50 = 0.131 µM; BuChE, IC50 = 0.116 µM; SI = 1.13), significant inhibition of Aß(1-42) aggregation (55.7%, at 5 µM) and acceptable neuroprotective activity. Extensive analysis of in vitro and in vivo assays indicates that new cyclopentaquinoline derivatives offer promise as candidates for new anti-AD drugs.

Synthesis, In Vitro, and Computational Studies of PTP1B Phosphatase Inhibitors Based on Oxovanadium(IV) and Dioxovanadium(V) Complexes.

One of the main goals of recent bioinorganic chemistry studies has been to design and synthesize novel substances to treat human diseases. The promising compounds are metal-based and metal ion binding components such as vanadium-based compounds. The potential anticancer action of vanadium-based compounds is one of area of investigation in this field. In this study, we present five oxovanadium(IV) and dioxovanadium(V) complexes as potential PTP1B inhibitors with anticancer activity against the MCF-7 breast cancer cell line, the triple negative MDA-MB-231 breast cancer cell line, and the human keratinocyte HaCaT cell line. We observed that all tested compounds were effective inhibitors of PTP1B, which correlates with anticancer activity. [VO(dipic)(dmbipy)]·2 H2O (Compound 4) and [VOO(dipic)](2-phepyH)·H2O (Compound 5) possessed the greatest inhibitory effect, with IC50 185.4 ± 9.8 and 167.2 ± 8.0 nM, respectively. To obtain a better understanding of the relationship between the structure of the examined compounds and their activity, we performed a computer simulation of their binding inside the active site of PTP1B. We observed a stronger binding of complexes containing dipicolinic acid with PTP1B. Based on our simulations, we suggested that the studied complexes exert their activity by stabilizing the WPD-loop in an open position and limiting access to the P-loop.

Pyridinium-2-carbaldoximes with quinolinium carboxamide moiety are simultaneous reactivators of acetylcholinesterase and butyrylcholinesterase inhibited by nerve agent surrogates.

The pyridinium-2-carbaldoximes with quinolinium carboxamide moiety were designed and synthesised as cholinesterase reactivators. The prepared compounds showed intermediate-to-high inhibition of both cholinesterases when compared to standard oximes. Their reactivation ability was evaluated in vitro on human recombinant acetylcholinesterase (hrAChE) and human recombinant butyrylcholinesterase (hrBChE) inhibited by nerve agent surrogates (NIMP, NEMP, and NEDPA) or paraoxon. In the reactivation screening, one compound was able to reactivate hrAChE inhibited by all used organophosphates and two novel compounds were able to reactivate NIMP/NEMP-hrBChE. The reactivation kinetics revealed compound 11 that proved to be excellent reactivator of paraoxon-hrAChE better to obidoxime and showed increased reactivation of NIMP/NEMP-hrBChE, although worse to obidoxime. The molecular interactions of studied reactivators were further identified by in silico calculations. Molecular modelling results revealed the importance of creation of the pre-reactivation complex that could lead to better reactivation of both cholinesterases together with reducing particular interactions for lower intrinsic inhibition by the oxime.

Multidirectional in vitro and in cellulo studies as a tool for identification of multi-target-directed ligands aiming at symptoms and causes of Alzheimer's disease.

Effective therapy of Alzheimer's disease (AD) requires treatment with a combination of drugs that modulate various pathomechanisms contributing to the disease. In our research, we have focused on the development of multi-target-directed ligands - 5-HT6 receptor antagonists and cholinesterase inhibitors - with disease-modifying properties. We have performed extended in vitro (FRET assay) and in cellulo (Escherichia coli model of protein aggregation) studies on their ß-secretase, tau, and amyloid ß aggregation inhibitory activity. Within these multifunctional ligands, we have identified compound 17 with inhibitory potency against tau and amyloid ß aggregation in in cellulo assay of 59% and 56% at 10 µM, respectively, hBACE IC50=4 µM, h5TH6 K i=94 nM, hAChE IC50=26 nM, and eqBuChE IC50=5 nM. This study led to the development of multifunctional ligands with a broad range of biological activities crucial not only for the symptomatic but also for the disease-modifying treatment of AD.

New Tetrahydroacridine Hybrids with Dichlorobenzoic Acid Moiety Demonstrating Multifunctional Potential for the Treatment of Alzheimer's Disease.

A series of new tetrahydroacridine and 3,5-dichlorobenzoic acid hybrids with different spacers were designed, synthesized, and evaluated for their ability to inhibit both cholinesterase enzymes. Compounds 3a, 3b, 3f, and 3g exhibited selective butyrylcholinesterase (EqBuChE) inhibition with IC50 values ranging from 24 to 607 nM. Among them, compound 3b was the most active (IC50 = 24 nM). Additionally, 3c (IC50 for EeAChE = 25 nM and IC50 for EqBuChE = 123 nM) displayed dual cholinesterase inhibitory activity and was the most active compound against acetylcholinesterase (AChE). Active compound 3c was also tested for the ability to inhibit Aß aggregation. Theoretical physicochemical properties of the compounds were calculated using ACD Labs Percepta and Chemaxon. A Lineweaver-Burk plot and docking study showed that 3c targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Moreover, 3c appears to possess neuroprotective activity and could be considered a free-radical scavenger. In addition, 3c did not cause DNA damage and was found to be less toxic than tacrine after oral administration; it also demonstrated little inhibitory activity towards hyaluronidase (HYAL), which may indicate that it possesses anti-inflammatory properties. The screening for new in vivo interactions between 3c and known receptors was realized by yeast three-hybrid technology (Y3H).

Dual Action of Dipyridothiazine and Quinobenzothiazine Derivatives-Anticancer and Cholinesterase-Inhibiting Activity.

The inverse correlation observed between Alzheimer's disease (AD) and cancer has prompted us to look for cholinesterase-inhibiting activity in phenothiazine derivatives that possess anticancer properties. With the use of in silico and in vitro screening methods, our study found a new biological activity in anticancer polycyclic, tricyclic, and tetracyclic compounds. The virtual screening of a library of 120 ligands, which are the derivatives of azaphenothiazine, led to the identification of 25 compounds that can act as potential inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Biological assays revealed the presence of selective inhibitors of eeAChE (electric eel AChE) or eqBuChE (equine serum BuChE) and nonselective inhibitors of both enzymes among the tested compounds. Their potencies against eeAChE were in a submicromolar-to-micromolar range with IC50 values from 0.78 to 19.32 µM, while their IC50 values against eqBuChE ranged from 0.46 to 10.38 µM. The most potent among the compounds tested was the tetracyclic derivative, 6-(4-diethylaminobut-2-ynyl)-9-methylthioquinobenzothiazine 24, which was capable of inhibiting both enzymes. 9-Fluoro-6-(1-piperidylethyl)quinobenzothiazine 23 was found to act as a selective inhibitor of eqBuChE with an IC50 value of 0.46 µM. Compounds with such a dual antitumor and cholinesterase-inhibitory activity can be considered as a valuable combination for the treatment of both cancer and AD prevention. The results presented in this study might open new directions of research on the group of tricyclic phenothiazine derivatives.

Search for multifunctional agents against Alzheimer's disease among non-imidazole histamine H3 receptor ligands. In vitro and in vivo pharmacological evaluation and computational studies of piperazine derivatives.

In the search for new treatments for complex disorders such as Alzheimer's disease the Multi-Target-Directed Ligands represent a very promising approach. The aim of the present study was to identify multifunctional compounds among several series of non-imidazole histamine H3 receptor ligands, derivatives of 1-[2-thiazol-5-yl-(2-aminoethyl)]-4-n-propylpiperazine, 1-[2-thiazol-4-yl-(2-aminoethyl)]-4-n-propylpiperazine and 1-phenoxyalkyl-4-(amino)alkylopiperazine using in vitro and in vivo pharmacological evaluation and computational studies. Performed in vitro assays showed moderate potency of tested compounds against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Molecular modeling studies have revealed possible interactions between the active compounds and both AChE and BuChE as well as the human H3 histamine receptor. Computational studies showed the high drug-likeness of selected compounds with very good physicochemical profiles. The parallel artificial membrane permeation assay proved outstanding blood-brain barrier penetration in test conditions. The most promising compound, A12, chemically methyl(4-phenylbutyl){2-[2-(4-propylpiperazin-1-yl)-1,3-thiazol-5-yl]ethyl}amine, possesses good balanced multifunctional profile with potency toward studied targets - H3 antagonist activity (pA2 = 8.27), inhibitory activity against both AChE (IC50 = 13.96 µM), and BuChE (IC50 = 14.62 µM). The in vivo pharmacological studies revealed the anti-amnestic properties of compound A12 in the passive avoidance test on mice.

Discovery of New Cyclopentaquinoline Analogues as Multifunctional Agents for the Treatment of Alzheimer's Disease.

Here we report the two-step synthesis of 8 new cyclopentaquinoline derivatives as modifications of the tetrahydroacridine structure. Next, the biological assessment of each of them was performed. Based on the obtained results we identified 6-chloro-N-[2-(2,3-dihydro-1H-cyclopenta[b]quinolin-9-ylamino)-hexyl]]-nicotinamide hydrochloride (3e) as the most promising compound with inhibitory potencies against EeAChE and EqBuChE in the low nanomolar level 67 and 153 nM, respectively. Moreover, 3e compound is non-hepatotoxic, able to inhibit amyloid beta aggregation, and shows a mix-type of cholinesterase's inhibition. The mixed type of inhibition of the compound was confirmed by molecular modeling. Then, yeast three-hybrid (Y3H) technology was used to confirm the known ligand-receptor interactions. New derivatives do not show antioxidant activity (confirmed by the use of two different tests). A pKa assay method was developed to identify the basic physicochemical properties of 3e compound. A LogP assay confirmed that 3e compound fulfills Lipinsky's rule of five.

Novel carbamate derivatives as selective butyrylcholinesterase inhibitors.

Selective butyrylcholinesterase inhibitors could be the promising drug candidates, used in treatment of Alzheimer's disease. The study describes the synthesis and biological activity of novel carbamate derivatives with N-phenylpiperazine, N-benzylpiperazine and 4-benzylpiperidine moieties. Biological studies revealed that most of these compounds displayed significant activity against BuChE. Compound 16 (3-(4-phenyl-piperazin-1-ylmethyl)-phenyl phenylcarbamate) turned out to be the most active (IC50 = 2.00 µM for BuChE). For all synthesized compounds lipophilicity and other physicochemical properties were calculated using computer programs. Relationship between these properties and activity was also checked. Binding mode with enzyme and the ensuing differences in activity were explained by the molecular modeling studies.

Design, Synthesis, and Biological Evaluation of 2-(Benzylamino-2-Hydroxyalkyl)Isoindoline-1,3-Diones Derivatives as Potential Disease-Modifying Multifunctional Anti-Alzheimer Agents.

The complex nature of Alzheimer's disease calls for multidirectional treatment. Consequently, the search for multi-target-directed ligands may lead to potential drug candidates. The aim of the present study is to seek multifunctional compounds with expected activity against disease-modifying and symptomatic targets. A series of 15 drug-like various substituted derivatives of 2-(benzylamino-2-hydroxyalkyl)isoindoline-1,3-diones was designed by modification of cholinesterase inhibitors toward ß-secretase inhibition. All target compounds have been synthesized and tested against eel acetylcholinesterase (eeAChE), equine serum butyrylcholinesterase (eqBuChE), human ß-secretase (hBACE-1), and ß-amyloid (Aß-aggregation). The most promising compound, 12 (2-(5-(benzylamino)-4-hydroxypentyl)isoindoline-1,3-dione), displayed inhibitory potency against eeAChE (IC50 = 3.33 µM), hBACE-1 (43.7% at 50 µM), and Aß-aggregation (24.9% at 10 µM). Molecular modeling studies have revealed possible interaction of compound 12 with the active sites of both enzymes-acetylcholinesterase and ß-secretase. IN CONCLUSION: modifications of acetylcholinesterase inhibitors led to the discovery of a multipotent anti-Alzheimer's agent, with moderate and balanced potency, capable of inhibiting acetylcholinesterase, a symptomatic target, and disease-modifying targets: ß-secretase and Aß-aggregation.

Tetrahydroacridine derivatives with fluorobenzoic acid moiety as multifunctional agents for Alzheimer's disease treatment.

A novel series of 9-amino-1,2,3,4-tetrahydroacridine derivatives with 2-fluorobenzoic acid or 3-fluorobenzoic acid moiety were designed, synthesized and evaluated as inhibitors of cholinesterases and aggregation of ß-amyloid. In the study target compounds were very potent inhibitors of AChE and BChE. The most promising agents had higher inhibitory potency than the reference drugs which was tacrine. Ultimately, the kinetic assay shows the most active target compound 3c against AChE. Almost all of them were more potent against BChE than AChE. Compound 3c in various concentrations was tested by aggregation experiment. Inhibition of ß-amyloid aggregation was 77.32% and 80.43% at 50µM and 100µM, respectively. Therefore, compound 3c is a promising agent for the treatment of AD.

New cyclopentaquinoline hybrids with multifunctional capacities for the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is the most common progressive form of brain neurodegeneration and the most prevailing cause of dementia. Unfortunately, the aetiology of AD is not completely studied but different factors are associated with the development of AD such as among others low level of acetylcholine, aggregation of ß-amyloid (Aß), hyperphosphorylated tau protein, oxidative stress, and inflammation. The study encompass organic syntheses of 2,3-dihydro-1H-cyclopenta[b]quinoline with 5,6-dichloronicotinic acid and suitable linkers derivatives as multifunctional agents for AD treatment. Afterwards self-induced amyloid beta aggregation, inhibition studies of acetylcholinesterase and butyrylcholinesterase and molecular docking studies were performed. The results showed that 3b compound exhibited the best acetylcholinesterase inhibitory activity, with IC50 value of 0.052 µM which is lower compared to references. Besides, all synthesised compounds showed good butyrylcholinesterase inhibitory activity with IC50 values from 0.071 to 0.797 µM. Compound 3b exhibited strong Aß1-42 aggregation inhibitory effect with 25.7% at 5 µM to 92.8% at 100 µM as well as good anti-inflammatory effect. Thus, new compounds could create new perspectives for further development as a multi-target-directed agent for AD treatment.

Cholinesterase inhibitory activity of chlorophenoxy derivatives-Histamine H3 receptor ligands.

In recent years, multitarget-directed ligands have become an interesting strategy in a search for a new treatment of Alzheimer's disease. Combination of both: a histamine H3 receptor antagonist/inverse agonist and a cholinesterases inhibitor in one molecule could provide a new therapeutic opportunity. Here, we present biological evaluation of histamine H3 receptor ligands-chlorophenoxyalkylamine derivatives against cholinesterases: acetyl- and butyrylcholinesterase. The target compounds showed cholinesterase inhibitory activity in a low micromolar range. The most potent in this group was 1-(7-(4-chlorophenoxy)heptyl)homopiperidine (18) inhibiting the both enzymes (EeAChE IC50=1.93µM and EqBuChE IC50=1.64µM). Molecular modeling studies were performed to explain the binding mode of 18 with histamine H3 receptor as well as with cholinesterases.

Novel biphenyl bis-sulfonamides as acetyl and butyrylcholinesterase inhibitors: Synthesis, biological evaluation and molecular modeling studies.

A series of new biphenyl bis-sulfonamide derivatives 2a-3p were synthesized in good to excellent yield (76-98%). The inhibitory potential of the synthesized compounds on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) was investigated. Most of the screened compounds showed modest in vitro inhibition for both AChE and BChE. Compared to the reference compound eserine (IC50 0.04 ± 0.0001 µM for AChE) and (IC50 0.85 ± 0.0001 µM for BChE), the IC50 values of these compounds were ranged from 2.27 ± 0.01 to 123.11 ± 0.04 µM for AChE and 7.74 ± 0.07 to <400 µM for BuChE. Among the tested compounds, 3p was found to be the most potent against AChE (IC50 2.27 ± 0.01 µM), whereas 3g exhibited the highest inhibition for BChE (IC50 7.74 ± 0.07 µM). Structure-activity relationship (SAR) of these compounds was developed and elaborated with the help of molecular docking studies.

Synthesis, biological evaluation and molecular modeling of new tetrahydroacridine derivatives as potential multifunctional agents for the treatment of Alzheimer's disease.

A novel series of 9-amino-1,2,3,4-tetrahydroacridine derivatives with 4-dimethylaminobenzoic acid moiety was synthesized and tested towards inhibition of cholinesterases and amyloid ß aggregation. Target compounds were designed as dual binding site cholinesterase inhibitors able to bind to both the catalytic and the peripheral site of the enzyme and therefore potentially endowed with other properties. The obtained derivatives were very potent inhibitors of both cholinesterases (EeAChE, EqBChE) with IC50 values ranging from sub-nanomolar to nanomolar range, and the inhibitory potency of the most promising agents was higher than that of the reference drugs (rivastigmine and tacrine). The kinetic studies of the most active compound 3a revealed competitive type of AChE inhibition. Moreover, all target compounds were more potent inhibitors of human AChE than tacrine with the most active compound 3b (IC50 = 19 nM). Compound 3a was also tested and displayed inhibitory potency against AChE-induced Aß 1-42 aggregation (80.6% and 91.3% at 50 µM and 100 µM screening concentration, respectively). Moreover, cytotoxicity assay performed on A549 cells did not indicate toxicity of this agent. Compound 3a is a promising candidate for further development of novel multi-functional agents in the therapy of AD.

Design and synthesis of new barbituric- and thiobarbituric acid derivatives as potent urease inhibitors: Structure activity relationship and molecular modeling studies.

In this study 36 new compounds were synthesized by condensing barbituric acid or thiobarbituric acid and respective anilines (bearing different substituents) in the presence of triethyl orthoformate in good yields. In vitro urease inhibition studies against jack bean urease revealed that barbituric acid derived compounds (1-9 and 19-27) were found to exhibit low to moderate activity however thiobarbituric acid derived compounds (10-18 and 28-36) showed significant inhibition activity at low micro-molar concentrations. Among the synthesized compounds, compounds (15), (12), (10), (36), (16) and (35) showed excellent urease inhibition with IC50 values 8.53 ± 0.027, 8.93 ± 0.027, 12.96 ± 0.13, 15 ± 0.098, 18.9 ± 0.027 and 19.7 ± 0.63 µM, respectively, even better than the reference compound thiourea (IC50 = 21 ± 0.011). The compound (11) exhibited comparable activity to the standard with IC50 value 21.83 ± 0.19 µM. In silico molecular docking studies for most active compounds (10), (12), (15), (16), (35) and (36) and two inactive compounds (3) and (6) were performed to predict the binding patterns.

Discovery of butyrylcholinesterase inhibitors among derivatives of azaphenothiazines.

The study presents the discovery of novel butyrylcholinesterase (BuChE) inhibitors among derivatives of azaphenothiazines by application of in silico and in vitro screening methods. From an in-house library of compounds, 143 heterocyclic molecules derived from the azaphenothiazine scaffold were chosen for virtual screening. Based on results of the docking procedure, 15 compounds were identified as exhibiting the best fit for the two screening complexes (ligand - AChE and ligand - BuChE). Five compounds displayed moderate AChE and good BuChE inhibitory activity at screening concentrations of 10 µM. The IC50 values for active BuChE inhibitors were in the 11.8-122.2 nM range. Three of the most active inhibitors are tetra- or pentacyclic derivatives of azaphenothiazines with the same N-methyl-2-piperidinethyl substituent.

Application of computational methods for the design of BACE-1 inhibitors: validation of in silico modelling.

ß-Secretase (BACE-1) constitutes an important target for search of anti-Alzheimer's drugs. The first inhibitors of this enzyme were peptidic compounds with high molecular weight and low bioavailability. Therefore, the search for new efficient non-peptidic inhibitors has been undertaken by many scientific groups. We started our work from the development of in silico methodology for the design of novel BACE-1 ligands. It was validated on the basis of crystal structures of complexes with inhibitors, redocking, cross-docking and training/test sets of reference ligands. The presented procedure of assessment of the novel compounds as ß-secretase inhibitors could be widely used in the design process.

New tacrine analogs as acetylcholinesterase inhibitors - theoretical study with chemometric analysis.

Computer simulations constitute the basis of the design and discovery of new drugs. This approach is not only significant with regards to finding new structures, but also for selecting the molecules with the highest probability of being useful in the diagnostic process and treatment of numerous diseases. In our work, we used computational software to analyze 32 new acetylcholinesterase (AChE) inhibitors and formulate ADMET predictions. To understand the influence of the structure of our derivatives on binding mode, we docked all structures to the active site of AChE and assigned some pharmacophoric features. Finally, we undertook a chemometric analysis of all the compounds on the basis of FT-IR, which gave us the possibility of performing a fast categorization of the analyzed compounds and design compounds with similar structures.

2-(4-Fluorophenyl)-1H-benzo[d]imidazole as a Promising Template for the Development of Metabolically Robust, α1ß2γ2GABA-A Receptor-Positive Allosteric Modulators.

Modulation of α1ß2γ2GABA-A receptor subpopulation expressed in the basal ganglia region is a conceptually novel mode of pharmacological strategy that offers prospects to tackle a variety of neurological dysfunction. Although clinical findings provided compelling evidence for the validity of this strategy, the current chemical space of molecules able to modulate the α1/γ2 interface of the GABA-A receptor is limited to imidazo[1,2-a]pyridine derivatives that undergo rapid biotransformation. In response to a deficiency in the chemical repertoire of GABA-A receptors, we identified a series of 2-(4-fluorophenyl)-1H-benzo[d]imidazoles as positive allosteric modulators (PAMs) with improved metabolic stability and reduced potential for hepatotoxicity, where lead molecules 9 and 23 displayed interesting features in a preliminary investigation. We further disclose that the identified scaffold shows a preference for interaction with the α1/γ2 interface of the GABA-A receptor, delivering several PAMs of the GABA-A receptor. The present work provides useful chemical templates to further explore the therapeutic potential of GABA-A receptor ligands and enriches the chemical space of molecules suitable for the interaction with the α1/γ2 interface.