Multitarget-Directed Ligands Hitting Serotonin Receptors: A Medicinal Chemistry Survey.

Serotonin (5-hydroxytryptamine, 5-HT) is a ubiquitous neurotransmitter in the human body. In the central nervous system, 5-HT affects sleep, pain, mood, appetite, and attention, while in the peripheral nervous system, 5-HT modulates peristalsis, mucus production, and blood vessel dilation. Fourteen membrane receptors mediate 5-HT activity. In agreement with the crucial roles played by 5-HT, many drugs target 5-HT receptors (5-HTRs). Therefore, it is unsurprising that many efforts have been devoted to discovering multitarget-directed ligands (MTDLs) capable of engaging one or more 5-HTRs plus another target phenotypically linked to a particular disease. In this review, we will describe medicinal chemistry efforts in designing MTDLs encompassing activity for one or more 5-HTRs, starting with atypical antipsychotics and moving to dual 5-HT1AR/serotonin transporter ligands, 5-HT6R antagonists/acetyl cholinesterases inhibitors, and 5-HT4R agonists/acetyl cholinesterases inhibitors. We will also provide an outlook on the most recent efforts made in the field.

Advances in Cholinesterase Inhibitor Research-An Overview of Preclinical Studies of Selected Organoruthenium(II) Complexes.

Cholinesterase (ChE) inhibitors are crucial therapeutic agents for the symptomatic treatment of certain chronic neurodegenerative diseases linked to functional disorders of the cholinergic system. Significant research efforts have been made to develop novel derivatives of classical ChE inhibitors and ChE inhibitors with novel scaffolds. Over the past decade, ruthenium complexes have emerged as promising novel therapeutic alternatives for the treatment of neurodegenerative diseases. Our research group has investigated a number of newly synthesized organoruthenium(II) complexes for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Three complexes (C1a, C1-C, and C1) inhibit ChE in a pharmacologically relevant range. C1a reversibly inhibits AChE and BChE without undesirable peripheral effects, making it a promising candidate for the treatment of Alzheimer's disease. C1-Cl complex reversibly and competitively inhibits ChEs, particularly AChE. It inhibits nerve-evoked skeletal muscle twitch and tetanic contraction in a concentration-dependent manner with no effect on directly elicited twitch and tetanic contraction and is promising for further preclinical studies as a competitive neuromuscular blocking agent. C1 is a selective, competitive, and reversible inhibitor of BChE that inhibits horse serum BChE (hsBChE) without significant effect on the peripheral neuromuscular system and is a highly species-specific inhibitor of hsBChE that could serve as a species-specific drug target. This research contributes to the expanding knowledge of ChE inhibitors based on ruthenium complexes and highlights their potential as promising therapeutic candidates for chronic neurodegenerative diseases.

Naturally Inspired Coumarin Derivatives in Alzheimer's Disease Drug Discovery: Latest Advances and Current Challenges.

The main feature of neurodegenerative diseases, including Alzheimer's disease, is the network of complex and not fully recognized neuronal pathways and targets involved in their onset and progression. The therapeutic treatment, at present mainly symptomatic, could benefit from a polypharmacological approach based on the development of a single molecular entity designed to simultaneously modulate different validated biological targets. This strategy is principally based on molecular hybridization, obtained by linking or merging different chemical moieties acting with synergistic and/or complementary mechanisms. The coumarin core, widely found in nature, endowed with a recognized broad spectrum of pharmacological activities, large synthetic accessibility and favourable pharmacokinetic properties, appears as a valuable, privileged scaffold to be properly modified in order to obtain compounds able to engage different selected targets. The scientific literature has long been interested in the multifaceted profiles of coumarin derivatives, and in this review, a survey of the most important results of the last four years, on both natural and synthetic coumarin-based compounds, regarding the development of anti-Alzheimer's compounds is reported.

Identification and Functional Characterization of Carboxylesterase Genes Involved in Spirodiclofen Resistance in Panonychus citri (McGregor).

Overexpression of carboxyl/cholinesterase (CCE) genes has been reported to be associated with many cases of pesticide resistance in arthropods. However, it has been rarely documented that CCE genes participate in spirodiclofen resistance in Panonychus citri. In previous research, we found that spirodiclofen resistance is related to increased P450 and CCE enzyme activities in P. citri. In this study, we identified two CCE genes, PcCCE3 and PcCCE5, which were significantly upregulated in spirodiclofen-resistant strain and after exposure to spirodiclofen. RNA interference of PcCCE3 and PcCCE5 increased the spirodiclofen susceptibility in P. citri. In vitro metabolism indicated that PcCCE3 and PcCCE5 could interact with spirodiclofen, but metabolites were detected only in the PcCCE3 treatment. Our results indicated that PcCCE3 participates in spirodiclofen resistance through direct metabolism, and PcCCE5 may be involved in the spirodiclofen resistance by passive binding and sequestration, which provides new insights into spirodiclofen resistance in P. citri.

Synthesis and Biological Evaluation of Colchicine─Aryl/Alkyl Amine Hybrids as Potential Noncytotoxic Cholinesterase Inhibitors: Identification of SBN-284 as a Dual Inhibitor of Cholinesterases and NLRP3 Inflammasome.

Colchicine, one of the oldest anti-inflammatory natural products still used clinically, inhibits NF-κB signaling and NLRP3 inflammasome activation. Despite its cytotoxicity and narrow therapeutic range, colchicine continues to intrigue medicinal chemists exploring its anti-inflammatory potential. This study aimed to investigate the colchicine scaffold for its role in Alzheimer's disease by targeting neuroinflammation and cholinesterases. Molecular docking revealed that colchicine's hydrophobic trimethoxyphenyl framework can potentially bind to the peripheral anionic site of cholinesterases. Hybrid structures combining colchicine with aryl/alkyl amines were designed to bind both peripheral and catalytic sites of cholinesterases. We describe here the design, synthesis, and in vitro cytotoxicity evaluation of these colchicine-aryl/alkyl amine hybrids, along with their in silico interactions with the cholinesterase active site gorge. Nontoxic analogs demonstrating strong cholinesterase binding affinity were further evaluated for their anticholinesterase and antineuroinflammatory activities. The colchicine-donepezil hybrid, SBN-284 (3x), inhibited both acetylcholinesterase and butyrylcholinesterase as well as the NLRP3 inflammasome complex at low micromolar concentrations. It achieved this through noncompetitive inhibition, occupying the active site gorge and interacting with both peripheral and catalytic anionic sites of cholinesterases. Analog 3x was shown to cross the blood-brain barrier and exhibited no toxicity to neuronal cells, primary macrophages, or epithelial fR2 cells. These findings highlight the potential of this lead compound for further preclinical investigation as a promising anti-Alzheimer agent.

Design and discovery of anthranilamide derivatives as a potential treatment for neurodegenerative disorders via targeting cholinesterases and monoamine oxidases.

Neurodegenerative diseases with progressive cellular loss of the central nervous system and elusive disease etiology provide a continuous impetus to explore drug discovery programmes aiming at identifying robust and effective inhibitors of cholinesterase and monoamine oxidase enzymes. We herein present a concise library of anthranilamide derivatives involving a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction to install the diverse structural diversity required for the desired biological action. Using Ellman's method, cholinesterase inhibitory activity was performed against AChE and BuChE enzymes. In vitro assay results demonstrated that anthranilamides are potent inhibitors with remarkable potency. Compound 6k emerged as the lead candidate and dual inhibitor of both enzymes with IC50 values of 0.12 ± 0.01 and 0.49 ± 0.02 µM against AChE and BuChE, respectively. Several other compounds were found as highly potent and selective inhibitors. Anthranilamide derivatives were also tested against monoamine oxidase (A and B) enzymes using fluorometric method. In vitro data revealed compound 6h as the most potent inhibitor against MAO-A, showing an IC50 value of 0.44 ± 0.02 µM, whereas, compound 6k emerged as the top inhibitor of MAO-B with an IC50 value of 0.06 ± 0.01 µM. All the lead inhibitors were analyzed for the identification of their mechanism of action using Michaelis-Menten kinetics experiments. Compound 6k and 6h depicted a competitive mode of action against AChE and MAO-A, whereas, a non-competitive and mixed-type of inhibition was observed against BuChE and MAO-B by compounds 6k. Molecular docking analysis revealed remarkable binding affinities of the potent inhibitors with specific residues inside the active site of receptors. Furthermore, molecular dynamics simulations were performed to explore the ability of potent compounds to form energetically stable complexes with the target protein. Finally, in silico ADME calculations also demonstrated that the potent compounds exhibit promising pharmacokinetic profile, satisfying the essential criteria for drug-likeness. Altogether, the findings reported in the current work clearly suggest that the identified anthranilamide derivatives have the potential to serve as effective drug candidates for future investigations.

Towards cost-effective drug discovery: Reusable immobilized enzymes for neurological disease research.

Enzyme handling and utilization bears many challenges such as their limited stability, intolerance of organic solvents, high cost, or inability to reuse. Most of these limitations can be overcome by enzyme immobilization on the surface of solid support. In this work, the recombinant form of human cholinesterases and monoamine oxidases as important drug targets for neurological diseases were immobilized on the surface of magnetic non-porous microparticles by a non-covalent bond utilizing the interaction between a His-tag terminus on the recombinant enzymes and cobalt (Co2+) ions immobilized on the magnetic microparticles. This type of binding led to targeted enzyme orientation, which completely preserved the catalytic activity and allowed high reproducibility of immobilization. In comparison with free enzymes, the immobilized enzymes showed exceptional stability in time and the possibility of repeated use. Relevant Km, Vmax, and IC50 values using known inhibitors were obtained using particular immobilized enzymes. Such immobilized enzymes on magnetic particles could serve as an excellent tool for a sustainable approach in the early stage of drug discovery.

Antimicrobial, Herbicidal and pesticidal potential of Tunisian eucalyptus species: Chemoprofiling and biological evaluation.

The Eucalyptus genus, characterized by its imposing stature and fragrant foliage, has been a source of fascination for humanity over the centuries. The focus of the present investigation was directed towards the essentials oils (EOs) of five Eucalyptus trees cultivated in Tunisia. The GC-MS analysis unveiled unique compositional profiles, a finding substantiated by both Hierarchical Clustering Analysis (HCA) and Principal Component Analysis (PCA) conducted on the leaves EOs. These analyses resulted in the formation of discrete HCA clades, delineating 23 significant components. Notably, the percentage of eucalyptol emerged as the pivotal factor demarcating the separation between three distinct groups. The statistical analysis revealed a dose-dependent relationship in both phytotoxicity evaluation and antibacterial activity. The EOs from Eucalyptus loxophleba and E. salubris exhibited the highest phytotoxicity, inhibiting radical elongation and germination of various seeds, especially Sinapis arvensis and Raphanus sativus. The antimicrobial assessment demonstrated significant inhibitory effects of the EOs on bacterial strains, with MIC values spanning from 14 to exceeding 50 mg/ml. The EOs also affected biofilm formation and cellular metabolism, displaying varied efficacy among different Eucalyptus species against some bacterial strains. The EOs exhibited selective inhibition against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, and α-glucosidase. E. campaspe EO showed the highest AChE activity, while E. loxophleba and E. salubris EOs were most potent toward α-amylase. E. loxophleba EO demonstrated notable activity against α-glucosidase. Overall, these findings provide important data about the diverse biological activities of Eucalyptus EOs, suggesting potential applications in agriculture, medicine, and pharmacy.

New paradigms in the study of the cholinergic system and metabolic diseases: Acetyl-and-butyrylcholinesterase.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are enzymes that belong to the neuromuscular cholinergic system, their main function is to hydrolyze the neurotransmitter acetylcholine (ACh), through their hydrolysis these enzymes regulate the neuronal and neuromuscular cholinergic system. They have recently attracted considerable attention due to the discovery of new enzymatic and nonenzymatic functions. These discoveries have aroused the interest of numerous scientists, consolidating the relevance of this group of enzymes. Recent investigations have revealed a positive correlation between several risk factors for metabolic syndrome (MetS) and the expression of cholinesterases (ChE's), which underscore the impact of high ChE's activity on the pro-inflammatory state associated with MetS. In addition, the excessive hydrolysis of ACh and other choline esters (succinylcholine, propionylcholine, butyrylcholine, etc.) by both ChE's results in the overproduction of fatty acid precursor metabolites, which facilitate the synthesis of very low-density lipoproteins and triacylglycerols. Participation in these processes may represent the link between ChE's and metabolic disorders. However, further scientific research is required to fully elucidate the involvement of ChE's in metabolic diseases. This review aims to collect recent research studies that contribute to understanding the association between the cholinergic system and metabolic diseases.

In vitro and in silico investigation of FDA-approved drugs to be repurposed against Alzheimer's disease.

Alzheimer's disease (AD), one of the main causes of dementia, is a neurodegenerative disorder. Cholinesterase inhibitors are used in the treatment of AD, but prolonged use of these drugs can lead to serious side effects. Drug repurposing is an approach that aims to reveal the effectiveness of drugs in different diseases beyond their clinical uses. In this work, we investigated in vitro and in silico inhibitory effects of 11 different drugs on cholinesterases. The results showed that trimebutine, theophylline, and levamisole had the highest acetylcholinesterase inhibitory actions among the tested drugs, and these drugs inhibited by 68.70 ± 0.46, 53.25 ± 3.40, and 44.03 ± 1.20%, respectively at 1000 µM. In addition, these drugs are bound to acetylcholinesterase via competitive manner. Molecular modeling predicted good fitness in acetylcholinesterase active site for these drugs and possible central nervous system action for trimebutine. All of these results demonstrated that trimebutine was determined to be the drug with the highest potential for use in AD.

Organophosphate toxicity patterns: A new approach for assessing organophosphate neurotoxicity.

Organophosphorus compounds or organophosphates (OPs) are widely used as flame retardants, plasticizers, lubricants and pesticides. This contributes to their ubiquitous presence in the environment and to the risk of human exposure. The persistence of OPs and their bioaccumulative characteristics raise serious concerns regarding environmental and human health impacts. To address the need for safer OPs, this study uses a New Approach Method (NAM) to analyze the neurotoxicity pattern of 42 OPs. The NAM consists of a 4-step process that combines computational modeling with in vitro and in vivo experimental studies. Using spherical harmonic-based cluster analysis, the OPs were grouped into four main clusters. Experimental data and quantitative structure-activity relationships (QSARs) analysis were used in conjunction to provide information on the neurotoxicity profile of each group. Results showed that one of the identified clusters had a favorable safety profile, which may help identify safer OPs for industrial applications. In addition, the 3D-computational analysis of each cluster was used to identify meta-molecules with specific 3D features. Toxicity was found to correspond to the level of phosphate surface accessibility. Substances with conformations that minimize phosphate surface accessibility caused less neurotoxic effect. This multi-assay NAM could be used as a guide for the classification of OP toxicity, helping to minimize the health and environmental impacts of OPs, and providing rapid support to the chemical regulators, whilst reducing reliance on animal testing.

New Multitarget Rivastigmine-Indole Hybrids as Potential Drug Candidates for Alzheimer's Disease.

Alzheimer's disease (AD) is the most common form of dementia with no cure so far, probably due to the complexity of this multifactorial disease with diverse processes associated with its origin and progress. Several neuropathological hallmarks have been identified that encourage the search for new multitarget drugs. Therefore, following a multitarget approach, nine rivastigmine-indole (RIV-IND) hybrids (5a1-3, 5b1-3, 5c1-3) were designed, synthesized and evaluated for their multiple biological properties and free radical scavenging activity, as potential multitarget anti-AD drugs. The molecular docking studies of these hybrids on the active center of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) suggest their capacity to act as dual enzyme inhibitors with probable greater disease-modifying impact relative to AChE-selective FDA-approved drugs. Compounds 5a3 (IC50 = 10.9 µM) and 5c3 (IC50 = 26.8 µM) revealed higher AChE inhibition than the parent RIV drug. Radical scavenging assays demonstrated that all the hybrids containing a hydroxyl substituent in the IND moiety (5a2-3, 5b2-3, 5c2-3) have good antioxidant activity (EC50 7.8-20.7 µM). The most effective inhibitors of Aß42 self-aggregation are 5a3, 5b3 and 5c3 (47.8-55.5%), and compounds 5b2 and 5c2 can prevent the toxicity induced by Aß1-42 to cells. The in silico evaluation of the drug-likeness of the hybrids also showed that all the compounds seem to have potential oral availability. Overall, within this class of RIV-IND hybrids, 5a3 and 5c3 appear as lead compounds for anti-AD drug candidates, deserving further investigation.

Perioperative point-of-care-testing of plasmacholinesterases identifies older patients at risk for postoperative delirium: an observational prospective cohort study.

BACKGROUND: Postoperative delirium (POD) is a severe perioperative complication that may increase mortality and length-of-stay in older patients. Moreover, POD is a major economic burden to any healthcare system. An altered expression of Acetylcholine- and Butyrylcholinesterases (AChE, BuChE) due to an unbalanced neuroinflammatory response to trauma or an operative stimulus has been reported to play an essential role in the development of POD. We investigated if perioperative measurement of cholinesterases (ChEs) can help identifying patients at risk for the occurrence of POD in both, scheduled and emergency surgery patients. METHODS: This monocentric prospective observational cohort study was performed in a tertiary hospital (departments of orthopaedic surgery and traumatology). One hundred and fifty-one patients aged above 75 years were enrolled for scheduled (n = 76) or trauma-related surgery (n = 75). Exclusion criteria were diagnosed dementia and anticholinergic medication. Plasma samples taken pre- and postoperatively were analysed regarding AChE and BuChE activity. Furthermore, perioperative assessment using different cognitive tests was performed. The type of anaesthesia (general vs. spinal anaesthesia) was analysed. Primary outcome was the incidence of POD assessed by the approved Confusion Assessment Method (CAM) in combination with the expression of AChE and BuChE. RESULTS: Of 151 patients included, 38 (25.2%) suffered from POD; 11 (14%) in scheduled and 27 (36%) in emergency patients. AChE levels showed no difference throughout groups or time course. Trauma patients had lower BuChE levels prior to surgery than scheduled patients (p < 0.001). Decline in BuChE levels correlated positively with the incidence of POD (1669 vs. 1175 U/l; p < 0.001). Emergency patients with BuChE levels below 1556 U/L were at highest risk for POD. There were no differences regarding length of stay between groups or incidence of POD. The type of anaesthesia had no influence regarding the incidence of POD. Only Charlson Comorbidity Index and Mini Nutrition Assessment demonstrated reliable strength in respect of POD. CONCLUSIONS: Perioperative measurement of BuChE activity can be used as a tool to identify patients at risk of POD. As a point-of-care test, quick results may alter the patients' course prior to the development of POD. TRIAL REGISTRATION: https://drks.de/search/de/trial/DRKS00017178 .

Synthesis and biological evaluation of novel salicylidene uracils: Cytotoxic activity on human cancer cell lines and inhibitory action on enzymatic activity.

A series of salicylidene uracil (1-18) derived from 5-aminouracil and substituted salicylaldehydes were analyzed for cytotoxic activity and enzyme inhibitory potency. Nine out of eighteen derivatives (6-8, 10, 12-15, 18) are novel molecules synthesized for the first time in this work, and other derivatives were previously synthesized by our group. The compounds were characterized by Proton nuclear magnetic resonance, carbon nuclear magnetic resonance, fourier transform infrared spectroscopy, and elemental analysis. All compounds were tested for their in vitro cytotoxicity against PC-3 (human prostate adenocarcinoma), A549 (human alveolar adenocarcinoma), and SHSY-5Y (human neuroblastoma) cancer cell lines and the nontumorigenic HEK293 (human embryonic kidney cells) cell line. The 3,5-di-tert-butylsalicylaldehyde derived compound (8) was toxic to PC-3 human prostate adenocarcinoma cells, showing a promising IC50 value at 7.05 ± 0.76 µM. The present study also aimed to evaluate the inhibitory effects of the compounds against several key enzymes, namely carbonic anhydrase I and II (CA I and CA II), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and glutathione reductase (GR), which are implicated in various global disorders, such as Alzheimer's disease, epilepsy, cancer, malaria, diabetes, and glaucoma. The inhibitory profiles of the tested compounds were assessed by determining their Ki values, which ranged from 2.96 to 9.24 nM for AChE, 3.78 to 12.57 nM for BChE, 8.42 to 25.74 nM for CA I, 7.24 to 19.74 nM for CA II, and 0.541 to 1.124 µM for GR. Molecular docking studies were also performed for all compounds. Most derivatives exhibited much more effective inhibitory action compared with clinically used standards. Thus, our findings indicate that the salicylidene derivatives presented in this study are promising drug candidates that need further evaluation.

Toxicity Evaluation of Anti-cholinesterasic Amphibian Extracts by MTT and an Optimized Artemia salina Test.

The amphibian skin is an important source of bioactive compounds. Recently, our workgroup reported the bioactivity of new extracts from the Hylidae, Microhylidae and Leptodactylidae families against several pathways involved in Alzheimer's disease. However, since cytotoxicity can be a limiting factor for their applicability, we evaluated the toxicity of nine amphibian skin extracts with reported anticholinesterase activity, using the traditional MTT assay and an optimized Artemia salina test. The proposed improvement, guided by experimental design, aims to reduce the amount of biological sample needed. Overall, we proved that the active extracts were non-toxic at effective concentration against cholinesterases (AChE/BChE), positioning the amphibian skin as a promising and preliminary safe source of bioactive compounds in the anti-Alzheimer's treatment. Interestingly, we demonstrated that both toxicity assays can discriminate between toxic and non-toxic samples. We propose the A. salina bioassay as a reliable and cost-effective alternative for early toxicity screening.

Novel quinazolinone Derivatives: Design, synthesis and in vivo evaluation as potential agents targeting Alzheimer disease.

Since Alzheimer disease is one of the most prevalent types of dementia with a high mortality and disability rate, so development of multi-target drugs becomes the major strategy for battling AD. This study shows the development of a series of quinazolinone based derivatives as novel, multifunctional anti-AD drugs that exhibit both cholinesterase inhibitoryand anti-inflammatory properties. The preliminary results of the in vitro AChE inhibition activity showed that compounds 4b, 5a, 6f, 6h and 7b were better represented for further evaluation. Furthermore, in-vivo AChE inhibition activity and behavior Morris water maze test against donepezil as reference drug were evaluated. Additionally, hippocampal inflammatory markers; TNF-α, NFĸB, IL-1ß and IL-6 and antioxidant markers; SOD and MDA were assessed to evaluate the efficacy of quinazolinone derivatives against AD hallmarks. The results showed that 6f, 6h and 7b have promising anti-acetylcholinesterase, anti-inflammatory and antioxidant activities thus, have a significant effect in treatment of AD. Moreover, Histopathological examination revealed that 6f, 6h and 7b derivatives have neuroprotective effect against neuronal damage caused by induced scopolamine model in mice. Finally, the binding ability of the synthesized derivatives to the target, AChE was investigated through molecular docking which reflected significant interactions to the target based on their docking binding scores. Hence, the newly designed quinazolinone derivatives possess promising anti-acetylcholinesterase activity and challenging for the management of AD in the future.

Nicotinamide, an acetylcholinesterase uncompetitive inhibitor, protects the blood‒brain barrier and improves cognitive function in rats fed a hypercaloric diet.

Oxidative stress and inflammation induced by abundant consumption of high-energy foods and caloric overload are implicated in the dysfunction of the blood‒brain barrier (BBB), cognitive impairment, and overactivation of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). These enzymes hydrolyse acetylcholine, affecting anti-inflammatory cholinergic signalling. Our aim was to evaluate whether nicotinamide (NAM) attenuates the impairment of the BBB and cognitive function, improving cholinergic signalling. Forty male rats were distributed into five groups: one group was fed a standard diet, and the remaining groups were fed a high-fat diet and a beverage with 40% sucrose (HFS; high-fat sucrose). In three of the HFS groups, the carbohydrate was replaced by drinking water containing different concentrations of NAM for 5 h every morning for 12 weeks. The biochemical profile, levels of stress and inflammation markers, cholinesterase activities, BBB permeability, and cognitive capacity were evaluated. The results showed that the HFS diet disturbed the metabolism of carbohydrates and lipids, causing insulin resistance. Simultaneously, AChE and BChE activities, levels of proinflammatory cytokines, oxidation of proteins and lipoperoxidation increased along with decreased antioxidant capacity in serum. In the hippocampus, increased activity of cholinesterases, protein carbonylation and lipoperoxidation were associated with decreased antioxidant capacity. Systemic and hippocampal changes were reflected in increased BBB permeability and cognitive impairment. In contrast, NAM attenuated the above changes by reducing oxidative stress and inflammation through decreasing cholinesterase activities, especially by uncompetitive inhibition. NAM may be a potential systemic and neuroprotective agent to mitigate cognitive damage due to hypercaloric diets.

Galantamine-memantine hybrids for Alzheimer's disease: The influence of linker rigidity in biological activity and pharmacokinetic properties.

Neurodegenerative processes characterizing Alzheimer's disease (AD) are strictly related to the impairment of cholinergic and glutamatergic neurotransmitter systems which provoke synaptic loss. These experimental evidences still represent the foundation of the actual standard-of-care treatment for AD, albeit palliative, consisting on the coadministration of an acetylcholinesterase inhibitor and the NMDAR antagonist memantine. In looking for more effective treatments, we previously developed a series of galantamine-memantine hybrids where compound 1 (ARN14140) emerged with the best-balanced action toward the targets of interest paired to neuroprotective efficacy in a murine AD model. Unfortunately, it showed a suboptimal pharmacokinetic profile, which required intracerebroventricular administration for in vivo studies. In this work we designed and synthesized new hybrids with fewer rotatable bonds, which is related to higher brain exposure. Particularly, compound 2, bearing a double bond in the tether, ameliorated the biological profile of compound 1 in invitro studies, increasing cholinesterases inhibitory potencies and selective antagonism toward excitotoxic-related GluN1/2B NMDAR over beneficial GluN1/2A NMDAR. Furthermore, it showed increased plasma stability and comparable microsomal stability in vitro, paired with lower half-life and faster clearance in vivo. Remarkably, pharmacokinetic evaluations of compound 2 showed a promising increase in brain uptake in comparison to compound 1, representing the starting point for further chemical optimizations.

Pyrimidine-morpholine hybrids as potent druggable therapeutics for Alzheimer's disease: Synthesis, biochemical and in silico analyses.

The identification of effective and druggable cholinesterase inhibitors to treat progressive neurodegenerative Alzheimer's disorder remains a continuous drug discovery hunt. In this perspective, the present study investigates the design and discovery of pyrimidine-morpholine hybrids (5a-l) as potent cholinesterase inhibitors. Palladium-catalyzed Suzuki-Miyaura cross-coupling reaction was employed to introduce the structural diversity on the pyrimidine heterocyclic core. A range of commercially available boronic acids was successfully coupled showing a high functional group tolerance. In vitro cholinesterase inhibitory potential using Ellman's method revealed significantly strong potency. Compound 5h bearing a meta-tolyl substituent at 2-position of pyrimidine ring emerged as a lead candidate against AChE with an inhibitory potency of 0.43 ± 0.42 µM, ∼38-fold stronger value than neostigmine (IC50 = 16.3 ± 1.12 µM). Compound 5h also showed the lead inhibition against BuChE with an IC50 value of 2.5 ± 0.04 µM. The kinetics analysis of 5h revealed the non-competitive mode of inhibition against AChE whereas computational modelling results of potent leads depicted diverse contacts with the binding site amino acid residues. Molecular dynamics simulations revealed the stability of biomolecular system, while, ADME analysis demonstrated druglikeness behaviour of potent compounds. Overall, the investigated pyrimidine-morpholine scaffold presented a remarkable potential to be developed as efficacious anti-Alzheimer's drugs.

Novel Quinazolinone Derivatives: Potential Synthetic Analogs for the Treatment of Glaucoma, Alzheimer's Disease and Diabetes Mellitus.

Quinazolinones, which represent an important part of nitrogen-containing six-membered heterocyclic compounds, are frequently used in drug design due to their wide biological activity properties. Therefore, the novel quinazolinones were synthesized from the reaction of acylated derivatives of 4-hydroxy benzaldehyde with 3-amino-2-alkylquinazolin-4(3H)-ones with good yields (85-94 %) and their structures were characterized using Fourier-transform Infrared (FT-IR), Nuclear Magnetic Resonance (1 H-NMR, 13 C-NMR), and High-Resolution Mass Spectroscopy (HR-MS). As the application of the synthesized compounds, their inhibition properties of the synthesized compounds on α-Glucosidase (α-Glu), Acetylcholinesterase (AChE), Butyrylcholinesterase (BChE), and Carbonic anhydrase I-II (hCA I-II) metabolic enzymes were investigated. All compounds showed inhibition at nanomolar level with the Ki values in the range of 12.73±1.26-93.42±9.44 nM for AChE, 8.48±0.92-25.84±2.59 nM for BChE, 66.17±5.16-818.06±44.41 for α-Glu, 2.56±0.26-88.23±9.72 nM for hCA I, and 1.68±0.14-85.43±7.41 nM for hCA II. Molecular docking study was performed to understand the interactions of the most potent compounds with corresponding enzymes. Also, absorption, distribution, metabolism, excretion, and toxicity (ADME/T) properties of the compounds were investigated.