Tacrine for Alzheimer's disease

Structure-based inhibition of acetylcholinesterase and butyrylcholinesterase with 2-Aryl-6-carboxamide benzoxazole derivatives: synthesis, enzymatic assay, and in silico studies

An important research topic is the discovery of multifunctional compounds targeting different disease-causing components. This research aimed to design and synthesize a series of 2-aryl-6-carboxamide benzoxazole derivatives that inhibit cholinesterases on both the peripheral anionic and catalytic anionic sides. Compounds (7-48) were prepared from 4-amino-3-hydroxybenzoic acid in three steps. The Ellman test, molecular docking with Maestro, and molecular dynamics simulation studies with Desmond were done (Schrodinger, 12.8.117). Compound 36, the most potent compound among the 42 new compounds synthesized, had an inhibitory concentration of IC50 12.62 nM for AChE and IC50 25.45 nM for BChE (whereas donepezil was 69.3 nM and 63.0 nM, respectively). Additionally, compound 36 had docking values ​​of - 7.29 kcal/mol for AChE and - 6.71 kcal/mol for BChE (whereas donepezil was - 6.49 kcal/mol and - 5.057 kcal/mol, respectively). Furthermore, molecular dynamics simulations revealed that compound 36 is stable in the active gorges of both AChE (average RMSD: 1.98 Å) and BChE (average RMSD: 2.2 Å) (donepezil had average RMSD: 1.65 Å and 2.7 Å, respectively). The results show that compound 36 is a potent, selective, mixed-type dual inhibitor of both acetylcholinesterase and butyrylcholinesterase. It does this by binding to both the catalytically active and peripheral anionic sites of cholinesterases at the same time. These findings show that target compounds may be useful for establishing the structural basis for new anti-Alzheimer agents.

Sulfonamido, amido heterocyclic adducts of tetrazole derivatives as BACE1 inhibitors: in silico exploration

Alzheimer's disease is a neurodegenerative disorder accounting for 60-80% of dementia cases and is accompanied by a high mortality rate in patients above 70 years of age. The formation of senile plaques composed of amyloid-β protein is a hallmark of Alzheimer's disease. Beta-site APP cleaving enzyme 1 (BACE1) is a proteolytic enzyme involved in the degradation of amyloid precursor protein, which further degrades to form toxic amyloid-β fragments. Hence, inhibition of BACE1 was stated to be an effective strategy for Alzheimer's therapeutics. Keeping in mind the structures of different BACE1 inhibitors that had reached the clinical trials, we designed a library of compounds (total 164) based on a substituted 5-amino tetrazole scaffold which was an isosteric replacement of the cyclic amidine moiety, a common component of the BACE1 inhibitors which reached the clinical trials. The scaffold was linked to different structural moieties with the aid of an amide or sulfonamide bond to design some novel molecules. Molecular docking was initially performed and the top 5 molecules were selected based on docking scores and protein-ligand interactions. Furthermore, molecular dynamic simulations were performed for these molecules (3g, 7k, 8n, 9d, 9g) for 100 ns and MM-GBSA calculations were performed for each of these complexes. After critical evaluation of the obtained results, three potential molecules (9d, 8n, and 7k) were forwarded for prolonged stability studies by performing molecular dynamic simulations for 250 ns and simultaneous MM-GBSA calculations. It was observed that the compounds (9d, 8n, and 7k) were forming good interactions with the amino acid residues of the catalytic site of the enzyme with multiple non-covalent interactions. In MD simulations, the compounds have shown better stability and better binding energy throughout the runtime.

Multi-Target-Directed Cinnamic Acid Hybrids Targeting Alzheimer's Disease

Progressive cognitive decline in Alzheimer's disease (AD) is a growing challenge. Present therapies are based on acetylcholinesterase inhibition providing only temporary relief. Promising alternatives include butyrylcholinesterase (BuChE) inhibitors, multi-target ligands (MTDLs) that address the multi-factorial nature of AD, and compounds that target oxidative stress and inflammation. Cinnamate derivatives, known for their neuroprotective properties, show potential when combined with established AD agents, demonstrating improved efficacy. They are being positioned as potential AD therapeutic leads due to their ability to inhibit Aβ accumulation and provide neuroprotection. This article highlights the remarkable potential of cinnamic acid as a basic structure that is easily adaptable and combinable to different active groups in the struggle against Alzheimer's disease. Compounds with a methoxy substitution at the para-position of cinnamic acid display increased efficacy, whereas electron-withdrawing groups are generally more effective. The effect of the molecular volume is worthy of further investigation.

Nanotechnology-empowered therapeutics targeting neurodegenerative diseases

Neurodegenerative diseases are posing pressing health issues due to the high prevalence among aging populations in the 21st century. They are evidenced by the progressive loss of neuronal function, often associated with neuronal necrosis and many related devastating complications. Nevertheless, effective therapeutical strategies to treat neurodegenerative diseases remain a tremendous challenge due to the multisystemic nature and limited drug delivery to the central nervous system. As a result, there is a pressing need to develop effective alternative therapeutics to manage the progression of neurodegenerative diseases. By utilizing the functional reconstructive materials and technologies with specific targeting ability at the nanoscale level, nanotechnology-empowered medicines can transform the therapeutic paradigms of neurodegenerative diseases with minimal systemic side effects. This review outlines the current applications and progresses of the nanotechnology-enabled drug delivery systems to enhance the therapeutic efficacy in treating neurodegenerative diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Natural remedies for Alzheimer's disease: A systematic review of randomized controlled trials

Alzheimer's disease (AD) is the common type of dementia and is currently incurable. Existing FDA-approved AD drugs may not be effective for everyone, they cannot cure the disease nor stop its progression and their effects diminish over time. Therefore, the present review aimed to explore the role of natural alternatives in the treatment of AD. A systematic search was conducted using Ovid MEDLINE, CINAHL, Cochrane and PubMed databases and reference lists up to November 30, 2021. Only randomized control trials were included and appraised using the National Institute of Health framework. Data analysis showed that herbs like Gingko Biloba, Melissa Officinalis, Salvia officinalis, Ginseng and saffron alone or in combination with curcumin, low-fat diet, NuAD-Trail, and soy lecithin showed significant positive effects on AD. Moreover, combination of natural and pharmaceuticals has far better effects than only allopathic treatment. Thus, different herbal remedies in combination with FDA approved drugs are effective and more promising in treatment of AD.

Advances on Therapeutic Strategies for Alzheimer’s Disease: From Medicinal Plant to Nanotechnology

Alzheimer’s disease (AD) is a chronic dysfunction of neurons in the brain leading to dementia. It is characterized by gradual mental failure, abnormal cognitive functioning, personality changes, diminished verbal fluency, and speech impairment. It is caused by neuronal injury in the cerebral cortex and hippocampal area of the brain. The number of individuals with AD is growing at a quick rate. The pathology behind AD is the progress of intraneuronal fibrillary tangles, accumulation of amyloid plaque, loss of cholinergic neurons, and decrease in choline acetyltransferase. Unfortunately, AD cannot be cured, but its progression can be delayed. Various FDA-approved inhibitors of cholinesterase enzyme such as rivastigmine, galantamine, donepezil, and NDMA receptor inhibitors (memantine), are available to manage the symptoms of AD. An exhaustive literature survey was carried out using SciFinder’s reports from Alzheimer’s Association, PubMed, and Clinical Trials.org. The literature was explored thoroughly to obtain information on the various available strategies to prevent AD. In the context of the present scenario, several strategies are being tried including the clinical trials for the treatment of AD. We have discussed pathophysiology, various targets, FDA-approved drugs, and various drugs in clinical trials against AD. The goal of this study is to shed light on current developments and treatment options, utilizing phytopharmaceuticals, nanomedicines, nutraceuticals, and gene therapy.

Multi-Target Actions of Acridones from Atalantia monophylla towards Alzheimer's Pathogenesis and Their Pharmacokinetic Properties

Ten acridones isolated from Atalantia monophylla were evaluated for effects on Alzheimer’s disease pathogenesis including antioxidant effects, acetylcholinesterase (AChE) inhibition, prevention of beta-amyloid (Aβ) aggregation and neuroprotection. To understand the mechanism, the type of AChE inhibition was investigated in vitro and binding interactions between acridones and AChE or Aβ were explored in silico. Drug-likeness and ADMET parameters were predicted in silico using SwissADME and pKCSM programs, respectively. All acridones showed favorable drug-likeness and possessed multifunctional activities targeting AChE function, Aβ aggregation and oxidation. All acridones inhibited AChE in a mixed-type manner and bound AChE at both catalytic anionic and peripheral anionic sites. In silico analysis showed that acridones interfered with Aβ aggregation by interacting at the central hydrophobic core, C-terminal hydrophobic region, and the key residues 41 and 42. Citrusinine II showed potent multifunctional action with the best ADMET profile and could alleviate neuronal cell damage induced by hydrogen peroxide and Aβ_1-42 toxicity.

Comprehensive Review on Alzheimer's Disease: Causes and Treatment

Alzheimer’s disease (AD) is a disorder that causes degeneration of the cells in the brain and it is the main cause of dementia, which is characterized by a decline in thinking and independence in personal daily activities. AD is considered a multifactorial disease: two main hypotheses were proposed as a cause for AD, cholinergic and amyloid hypotheses. Additionally, several risk factors such as increasing age, genetic factors, head injuries, vascular diseases, infections, and environmental factors play a role in the disease. Currently, there are only two classes of approved drugs to treat AD, including inhibitors to cholinesterase enzyme and antagonists to N-methyl d-aspartate (NMDA), which are effective only in treating the symptoms of AD, but do not cure or prevent the disease. Nowadays, the research is focusing on understanding AD pathology by targeting several mechanisms, such as abnormal tau protein metabolism, β-amyloid, inflammatory response, and cholinergic and free radical damage, aiming to develop successful treatments that are capable of stopping or modifying the course of AD. This review discusses currently available drugs and future theories for the development of new therapies for AD, such as disease-modifying therapeutics (DMT), chaperones, and natural compounds.

Molecular Dynamics Revealing a Detour-Forward Release Mechanism of Tacrine: Implication for the Specific Binding Characteristics in Butyrylcholinesterase

Butyrylcholinesterase (BChE) is a non-specific enzyme with clinical pharmacological and toxicological significance, which was a renewed interest as therapeutic target in Alzheimer's disease (AD) nowadays. Here, all-atom molecular dynamics simulations of butyrylcholinesterase with tacrine complex were designed to characterize inhibitor binding modes, strengths, and the hydrogen-bond dependent non-covalent release mechanism. Four possible release channels were identified, and the most favorable channel was determined by random acceleration molecular dynamics molecular dynamics (RAMD MD) simulations. The thermodynamic and dynamic properties as well as the corresponding Detour-forward delivery mechanism were determined according to the classical molecular dynamics (MD) simulations accompanied with umbrella sampling. The free energy barrier of the tacrine release process for the most beneficial pathway is about 10.95 kcal/mol, which is related to the non-covalent interactions from the surrounding residues, revealing the specific binding characteristics in the active site. The residues including Asp70, Ser79, Trp82, Gly116, Thr120, Tyr332, and His438 were identified to play major roles in the stabilization of tacrine in the pocket of BChE, where hydrogen bonding and π-π interactions are significant factors. Tyr332 and Asp70, which act as gate keepers, play crucial roles in the substrate delivery. The present results provide a basic understanding for the ligand transport mechanism depending on the BChE enzymatic environment, which is useful for the design of BChE inhibitors in the future.

PLGA Microspheres with Alginate-Coated Large Pores for the Formulation of an Injectable Depot of Donepezil Hydrochloride

As the main symptom of Alzheimer's disease-related dementia is memory loss, patient compliance for donepezil hydrochloride (donepezil), administered as once-daily oral formulations, is poor. Thus, we aimed to design poly(lactic-co-glycolic acid) (PLGA) microspheres (MS) with alginate-coated large pores as an injectable depot of donepezil exhibiting sustained release over 2-3 weeks. The PLGA MS with large pores could provide large space for loading drugs with high loading capacity, and thereby sufficient amounts of drugs were considered to be delivered with minimal use of PLGA MS being injected. However, initial burst release of donepezil from the porous PLGA MS was observed. To reduce this initial burst release, the surface pores were closed with calcium alginate coating using a spray-ionotropic gelation method. The final pore-closed PLGA MS showed in vitro sustained release for approximately 3 weeks, and the initial burst release was remarkably decreased by the calcium alginate coating. In the prediction of plasma drug concentration profiles using convolution method, the mean residence time of the pore-closed PLGA MS was 2.7-fold longer than that of the porous PLGA MS. Therefore, our results reveal that our pore-closed PLGA MS formulation is a promising candidate for the treatment of dementia with high patient compliance.

Adhesion Molecule L1 Agonist Mimetics Protect Against the Pesticide Paraquat-Induced Locomotor Deficits and Biochemical Alterations in Zebrafish

Besides several endogenous elements, exogenous factors, including exposure to pesticides, have been recognized as putative factors contributing to the onset and development of neurodegenerative diseases, including Parkinson's disease (PD). Considering the availability, success rate, and limitations associated with the current arsenals to fight PD, there is an unmet need for novel therapeutic interventions. Therefore, based on the previously reported beneficial functions of the L1 cell adhesion molecule, we hypothesized that L1 mimetic compounds may serve to neutralize neurotoxicity triggered by the pesticide paraquat (PQ). In this study, we attempt to use PQ for inducing PD-like pathology and the L1 mimetic compounds phenelzine sulfate (PS) and tacrine (TC) as potential candidates for the amelioration of PD symptoms using zebrafish as a model system. Administration of PQ together with the L1 mimetic compounds PS or TC (250 nM) improved survival of zebrafish larvae, protected them from locomotor deficits, and increased their sensorimotor reflexes. Moreover, application of PQ together with PS (500 nM) or TC (1000 nM) in adult zebrafish counteracted PQ-induced toxicity, maintaining normal locomotor functions and spatial memory in an open field and T-maze task, respectively. Both L1 mimetic compounds prevented reduction in tyrosine hydroxylase and dopamine levels, reduced reactive oxygen species (ROS) generation, protected against impairment of mitochondrial viability, improved the antioxidant enzyme system, and prevented a decrease in ATP levels. Altogether, our findings highlight the beneficial functions of the agonistic L1 mimetics PS and TC by improving several vital cell functions against PQ-triggered neurotoxicity.

Tobacco smoking and its drug interactions with comedications involving CYP and UGT enzymes and nicotine

Tobacco smoking is a global public health threat causing several illnesses including cardiovascular disease (Myocardial infarction), cerebrovascular disease (Stroke), peripheral vascular disease (Claudication), chronic obstructive pulmonary disease, asthma, reduced female infertility, sexual dysfunction in men, different types of cancer and many other diseases. It has been estimated in 2015 that approximately 1.3 billion people smoke, around the globe. Use of medications among smokers is more common, nowadays. This review is aimed to identify the medications affected by smoking, involving Cytochrome P450 (CYP) and uridine diphosphate-glucuronosyltransferases (UGTs) enzymes and Nicotine. Polycyclic aromatic hydrocarbons (PAHs) of tobacco smoke have been associated with the induction of CYP enzymes such as CYP1A1, CYP1A2 and possibly CYP2E1 and UGT enzymes. The drugs metabolized by CYP1A1, CYP1A2, CYP2E1 and UGT enzymes might be affected by tobacco smoking and the smokers taking medications metabolized by those enzymes, may need higher doses due to decreased plasma concentrations through enhanced induction by PAHs of tobacco smoke. The prescribers and the pharmacists are required to be aware of medications affected by tobacco smoking to prevent the toxicity-associated complications during smoking cessation.

Therapeutic strategies and nano-drug delivery applications in management of ageing Alzheimer's disease

In recent years, the incidental rate of neurodegenerative disorders has increased proportionately with the aging population. Alzheimer's disease (AD) is one of the most commonly reported neurodegenerative disorders, and it is estimated to increase by roughly 30% among the aged population. In spite of screening numerous drug candidates against various molecular targets of AD, only a few candidates - such as acetylcholinesterase inhibitors are currently utilized as an effective clinical therapy. However, targeted drug delivery of these drugs to the central nervous system (CNS) exhibits several limitations including meager solubility, low bioavailability, and reduced efficiency due to the impediments of the blood-brain barrier (BBB). Current advances in nanotechnology present opportunities to overcome such limitations in delivering active drug candidates. Nanodrug delivery systems are promising in targeting several therapeutic moieties by easing the penetration of drug molecules across the CNS and improving their bioavailability. Recently, a wide range of nano-carriers, such as polymers, emulsions, lipo-carriers, solid lipid carriers, carbon nanotubes, metal based carriers etc., have been adapted to develop successful therapeutics with sustained release and improved efficacy. Here, we discuss few recently updated nano-drug delivery applications that have been adapted in the field of AD therapeutics, and future prospects on potential molecular targets for nano-drug delivery systems.

Identification of the optimal cognitive drugs among Alzheimer's disease: a Bayesian meta-analytic review

PURPOSE

The increasing prevalence of Alzheimer's disease (AD) demands more effective drugs, which are still unclear. The aim of this study is to compare the effectiveness of six drugs, such as donepezil, rivastigmine, galantamine, memantine, huperzine-A, and tacrine, in senior AD patients and identify the most effective one to improve patients' cognitive function.

METHODS

A system of search strategies was used to identify relevant studies including randomized controlled trials and clinical controlled trials evaluating the efficacy of six drugs in patients with AD. We updated relevant studies that were published before March 2018 as full-text articles. Using Bayesian network meta-analysis (NMA), we ranked cognitive ability objectively based on Mini-Mental State Examination (MMSE). Pairwise and NMAs were sequentially performed for the efficacy of drugs compared to each drug or control group through the trials included.

RESULTS

Among the 35 trials included, no obvious heterogeneity (I 2=0.0%, P=0.583) was revealed according to the pooled data for cognition in NMA and the mean difference (MD) of memantine (MD=1.7, 95% CI: 0.73, 2.8) showed that the memantine was significantly efficacious in the treatment group in terms of MMSE. Followed by galantamine, huperzine-A, rivastigmine, tacrine, and donepezil.

CONCLUSION

As the first NMA comparing the major drugs in market for AD, our study suggests that memantine might have a more significant benefit on cognition than other five drugs available.

Pharmacoepigenomic Interventions as Novel Potential Treatments for Alzheimer's and Parkinson's Diseases

Cerebrovascular and neurodegenerative disorders affect one billion people around the world and result from a combination of genomic, epigenomic, metabolic, and environmental factors. Diagnosis at late stages of disease progression, limited knowledge of gene biomarkers and molecular mechanisms of the pathology, and conventional compounds based on symptomatic rather than mechanistic features, determine the lack of success of current treatments, including current FDA-approved conventional drugs. The epigenetic approach opens new avenues for the detection of early presymptomatic pathological events that would allow the implementation of novel strategies in order to stop or delay the pathological process. The reversibility and potential restoring of epigenetic aberrations along with their potential use as targets for pharmacological and dietary interventions sited the use of epidrugs as potential novel candidates for successful treatments of multifactorial disorders involving neurodegeneration. This manuscript includes a description of the most relevant epigenetic mechanisms involved in the most prevalent neurodegenerative disorders worldwide, as well as the main potential epigenetic-based compounds under investigation for treatment of those disorders and their limitations.

Ethanol Extract of Oldenlandia diffusa Herba Attenuates Scopolamine-Induced Cognitive Impairments in Mice via Activation of BDNF, P-CREB and Inhibition of Acetylcholinesterase

Though Oldenlandia diffusa Herba (ODH) has been known to exhibit anti-cancer and anti-inflammatory effects, its anti-amnestic effect has never been reported so far. The aim of this present study was to elucidate the anti-amnestic effect of ODH. ODH pretreatment significantly reduced escape latency of scopolamine treated Institute of Cancer Research (ICR) mice compared to untreated control groups in a Morris water maze test. Similarly, the passive avoidance test showed that ODH treatment recovered the scopolamine induced amnesia in the ICR mouse model. Concentration of Ach in brains of ODH treated mice was increased compared to that of scopolamine treated mice. In addition, activity of acetylcholinesterase (AChE) was notably decreased by ODH. The protein expression of brain-derived neurotrophic factor (BDNF) and phospho-cAMP response element-binding protein (p-CREB) (Ser133) was increased in ODH pretreated group compared to control group. Consistently, immunohistochemistry (IHC) revealed the elevated expression of brain-derived neurotrophic factor (BDNF) and p-CREB in brains of ODH treated mice compared to the control group. Overall, these findings suggest that ODH has anti-amnestic potential via activation of BDNF and p-CREB and inhibition of AChE in mice with scopolamine induced amnesia.

Comparative Studies on Behavioral, Cognitive and Biomolecular Profiling of ICR, C57BL/6 and Its Sub-Strains Suitable for Scopolamine-Induced Amnesic Models

Cognitive impairment and behavioral disparities are the distinctive baseline features to investigate in most animal models of neurodegenerative disease. However, neuronal complications are multifactorial and demand a suitable animal model to investigate their underlying basal mechanisms. By contrast, the numerous existing neurodegenerative studies have utilized various animal strains, leading to factual disparity. Choosing an optimal mouse strain for preliminary assessment of neuronal complications is therefore imperative. In this study, we systematically compared the behavioral, cognitive, cholinergic, and inflammatory impairments of outbred ICR and inbred C57BL/6 mice strains subject to scopolamine-induced amnesia. We then extended this study to the sub-strains C57BL/6N and C57BL/6J, where in addition to the above-mentioned parameters, their endogenous antioxidant levels and cAMP response-element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) protein expression were also evaluated. Compared with the ICR strain, the scopolamine-inflicted C57BL/6 strains exhibited a substantial reduction of spontaneous alternation and an approximately two-fold increase in inflammatory protein expression, compared to the control group. Among the sub-strains, scopolamine-treated C57BL/6N strains exhibited declined step-through latency, elevated acetylcholinesterase (AChE) activity and inflammatory protein expression, associated with reduced endogenous antioxidant levels and p-CREB/BDNF expression, compared to the control and tacrine-treated groups. This indicates that the C57BL/6N strains exhibit significantly enhanced scopolamine-induced neuronal impairment compared to the other evaluated strains.

New Drugs from Marine Organisms in Alzheimer's Disease

Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder. Current approved drugs may only ameliorate symptoms in a restricted number of patients and for a restricted period of time. Currently, there is a translational research challenge into identifying the new effective drugs and their respective new therapeutic targets in AD and other neurodegenerative disorders. In this review, selected examples of marine-derived compounds in neurodegeneration, specifically in AD field are reported. The emphasis has been done on compounds and their possible relevant biological activities. The proposed drug development paradigm and current hypotheses should be accurately investigated in the future of AD therapy directions although taking into account successful examples of such approach represented by Cytarabine, Trabectedin, Eribulin and Ziconotide. We review a complexity of the translational research for such a development of new therapies for AD. Bryostatin is a prominent candidate for the therapy of AD and other types of dementia in humans.

QSAR analysis on tacrine-related acetylcholinesterase inhibitors

Background

The evaluation of the clinical effects of Tacrine has shown efficacy in delaying the deterioration of the symptoms of Alzheimer’s disease, while confirming the adverse events consisting mainly in the elevated liver transaminase levels. The study of tacrine analogs presents a continuous interest, and for this reason we establish Quantitative Structure-Activity Relationships on their Acetylcholinesterase inhibitory activity.

Results

Ten groups of new developed Tacrine-related inhibitors are explored, which have been experimentally measured in different biochemical conditions and AChE sources. The number of included descriptors in the structure-activity relationship is characterized by ‘Rule of Thumb’. The 1502 applied molecular descriptors could provide the best linear models for the selected Alzheimer’s data base and the best QSAR model is reported for the considered data sets.

Conclusion

The QSAR models developed in this work have a satisfactory predictive ability, and are obtained by selecting the most representative molecular descriptors of the chemical structure, represented through more than a thousand of constitutional, topological, geometrical, quantum-mechanical and electronic descriptor types.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-014-0084-0) contains supplementary material, which is available to authorized users.

Brain investigation and brain conceptualization

The brain of a patient with Alzheimer's disease (AD) undergoes changes starting many years before the development of the first clinical symptoms. The recent availability of large prospective datasets makes it possible to create sophisticated brain models of healthy subjects and patients with AD, showing pathophysiological changes occurring over time. However, these models are still inadequate; representations are mainly single-scale and they do not account for the complexity and interdependence of brain changes. Brain changes in AD patients occur at different levels and for different reasons: at the molecular level, changes are due to amyloid deposition; at cellular level, to loss of neuron synapses, and at tissue level, to connectivity disruption. All cause extensive atrophy of the whole brain organ. Initiatives aiming to model the whole human brain have been launched in Europe and the US with the goal of reducing the burden of brain diseases. In this work, we describe a new approach to earlier diagnosis based on a multimodal and multiscale brain concept, built upon existing and well-characterized single modalities.

Design and Synthesis of New Dual Binding Site Cholinesterase Inhibitors: in vitro Inhibition Studies with in silico Docking

Cholinesterases (ChEs) play a vital role in the regulation of cholinergic transmission. The inhibition of ChEs is considered to be involved in increasing acetylcholine level in the brain and thus has been implicated in the treatment of Alzheimer’s disease. We have designed and synthesized a series of novel indole derivatives and screened them for inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Most of the tested compounds exhibited inhibitory activity against AChE and BChE. Among them 4f and 6e showed the highest AChE inhibitory activity with IC₅₀ 91.21±0.06 and 68.52±0.04 μM, respectively. However compound 5a exhibited the highest inhibitory activity against BChE (IC₅₀ 55.21±0.12 μM).

Rehabilitating a brain with Alzheimer's: a proposal

Alzheimer's disease (AD) is the most common neurodegenerative disorder, originating sporadically in the population aged over 65 years, and advanced age is the principal risk factor leading to AD development. In spite of the large amount of research going on around the globe and all the information now available about AD, there is still no origin or triggering process known so far. Drugs approved for the treatment of AD include tacrine, donepezil, rivastigmine, galantamine, and memantine. These may delay or slow down the degenerative process for a while, but they can neither stop nor reverse its progression. Because that this might be due to a lack of effect of these drugs on degenerating neurons, even when they are able to potentiate the brain in nondegenerative conditions, we propose here an alternative therapy consisting of initial repair of neuronal membranes followed by conventional drug therapies. The rehabilitation of neurons in a degeneration process would enable the drugs to act more effectively on them and improve the effects of treatment in AD patients.

Present and prospective clinical therapeutic regimens for Alzheimer's disease

Alzheimer's disease (AD) is an incurable neurodegenerative disorder that produces cognitive impairments that increase in severity as the disease progresses. The clinical symptoms are related to the presence of neuritic plaques and neurofibrillary tangles in the cerebral cortex which represent the pathophysiological hallmarks of AD. The debilitating nature of the disease can result in clinical burden for the patient, emotional strain for those that care for patients with Alzheimer's, and significant financial burden to society. The goals of current treatments, such as cholinesterase inhibitors and N-methyl-D-aspartate receptor antagonist, are to reduce the severity or slow the progression of cognitive symptoms. Although these treatments have demonstrated modest clinical benefit, they are unable to prevent, prohibit, or reverse the underlying pathophysiology of AD. Considerable progress has been made toward the development of disease-modifying treatments. Treatments currently under development mainly target the production, aggregation, and removal of existing amyloid beta-peptide aggregates which are believed to instigate the overall development of the neuropathology. Additional strategies that target tau pathology are being studied to promote neural protection against AD pathology. The current research has continued to expand our knowledge toward the development of disease modifying Alzheimer's therapies; however, no specific treatment strategy capable of demonstrating empirical efficacy and safety has yet to emerge.

Dementia syndromes: evaluation and treatment

As our population ages, diseases affecting memory and daily functioning will affect an increasing number of individuals, their families and the healthcare system. The social, financial and economic impacts will be profound. This article provides an overview of current dementia syndromes to assist clinicians in evaluating, educating and treating these patients.

Comparative analysis of mortality in patients with Alzheimer's disease treated with donepezil or galantamine

BACKGROUND

few studies have analysed the effect of the long-term use of cholinesterase inhibitors (ChEIs) on mortality.

OBJECTIVE

to compare the long-term effects of galantamine and donepezil treatment on the mortality rate in Alzheimer's disease (AD) patients.

DESIGN

a retrospective cohort study.

SETTING AND SUBJECTS

404 patients referred by primary care centres to a Memory Clinic who were diagnosed with probable AD and who were prescribed treatment with donepezil or galantamine.

METHODS

standardised review of the patient's medical records.

RESULTS

14.5% of the patients showed intolerance to the treatment with ChEIs during the first 15 days. Of those patients who initially tolerated the treatment, 18.5% gave it up after a mean duration of 13.36 months and a mean dose of 7.5 mg/day of donepezil or 14.3 mg/day of galantamine. The mean duration of the treatment in patients who did not abandon the treatment was 25.4 months and the mean dose was 8.1 mg/day of donepezil or 20.0 mg/day of galantamine. There were no differences in the mortality rate between patients treated with donepezil or galantamine (13.7 versus 12.2; P = 0.75). The multivariate analysis through binary logistic regression showed that the variables associated with mortality were male gender, older age, heart failure, treatment with antipsychotic drugs and a high score on the Global Deterioration Scale.

CONCLUSIONS

the duration and the dose of donepezil or galantamine are not related to an increase in mortality. The related variables were advanced age, the severity of the dementia, being male, heart failure and treatment with antipsychotic drugs.

Treatment of cognitive dysfunction associated with Alzheimer's disease with cholinergic precursors. Ineffective treatments or inappropriate approaches?

The observations of the loss of cholinergic function in neocortex and hippocampus in Alzheimer's disease (AD) developed the hypothesis that replacement of cholinergic function may be of therapeutic benefit to AD patients. The different approaches proposed or tested included intervention with acetylcholine (ACh) precursors, stimulation of ACh release, use of muscarinic or nicotinic receptor agonists and acetylcholinesterase (AChE) or cholinesterase (ChE) inhibition. Inhibition of endogenous ACh degradation through ChE inhibitors and precursor loading were treatments more largely investigated in clinical trials. Of the numerous compounds in development for the treatment of AD, AChE and ChE inhibitors are the most clinically advanced, although clinical trials conducted to date did not always confirm a significant benefit of these drugs on all symptom domains of AD. The first attempts in the treatment of AD with cholinergic precursors did not confirm a clinical utility of this class of compounds in well controlled clinical trials. However, cholinergic precursors most largely used such as choline and phosphatidylcholine (lecithin) were probably not suitable for enhancing brain levels of ACh. Other phospholipids involved in choline biosynthetic pathways such as CDP-choline, choline alphoscerate and phosphatidylserine clearly enhanced ACh availability or release and provided a modest improvement of cognitive dysfunction in AD, these effects being more pronounced with choline alphoscerate. Although some positive results cannot be generalized due to the small numbers of patients studied, they probably would justify reconsideration of the most promising molecules in larger carefully controlled trials.