Against Alzheimer's Disease Research Articles

Genetic Evidence for Protective Effects of Angiotensin-Converting Enzyme Against Alzheimer Disease But Not Other Neurodegenerative Diseases in European Populations.

Background and ObjectivesAngiotensin-converting enzyme (ACE) inhibitors are a commonly prescribed class of medication used to treat heart failure, hypertension, and chronic kidney disease. However, previous observational studies have shown conflicting directions of associations between ACE inhibitors and risk of Alzheimer disease. Genetic evidence has supported a protective effect of cerebral ACE against Alzheimer disease (AD). However, it is unclear whether this effect is mediated through blood pressure and extends to other neurodegenerative diseases.MethodsWe performed genetic colocalization investigating an effect of cortical ACE expression on AD risk in people of European ancestry. We further investigated whether any effect of ACE expression on AD risk is mediated through changes in blood pressure and whether effects extend to Parkinson disease, small-vessel disease, or cognitive function in a Mendelian randomization paradigm.ResultsThere was genetic evidence supporting a protective effect of cortical ACE expression on AD risk in people of European ancestry. Although higher cortical ACE expression was associated with higher blood pressure, there was no strong evidence to support that its association with AD was mediated through blood pressure nor that ACE expression affected risk of other neurodegenerative traits.DiscussionGenetic evidence supports protective effects of cerebral ACE expression on AD, but not other neurodegenerative outcomes in people of European ancestry. Further work is required to investigate whether therapeutic inhibition of ACE increases risk of Alzheimer disease.

2,4-Diacetylphloroglucinol Reduces Beta-Amyloid Production and Secretion by Regulating ADAM10 and Intracellular Trafficking in Cellular and Animal Models of Alzheimer's Disease.

There is currently no effective treatment against Alzheimer’s disease (AD), although many strategies have been applied to reduce beta-amyloid (Aβ) levels. Here, we investigated 2,4-diacetylphloroglucinol (DAPG) effects on Aβ levels and mechanisms of action. DAPG was the most effective phloroglucinol derivative for reducing Aβ levels, without being toxic, in various models including HEK293 cells overexpressing Swedish mutant amyloid precursor protein (APP) (293sw), primary astrocytes isolated from APPsw/PS1dE9 transgenic mice, and after intrahippocampal injection of DAPG in APPsw/PS1dE9 transgenic mice. DAPG-mediated Aβ reduction was associated with increased soluble APPα (sAPPα) levels mediated by a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) but not ADAM17. ADAM10 inhibition in DAPG-treated cells prevented the effects on sAPPα but only partly on intracellular and secreted Aβ. To identify regulators of sAPPα and Aβ secretion, various inhibitors of intracellular trafficking were administered with DAPG. Brefeldin A (BFA) reversed DAPG-mediated changes in Aβ secretion in 293sw cells, whereas golgicide A (GCA) and BFA were effective in primary astrocytes, indicating a cell type-specific regulation of the trafficking. Moreover, GCA or BFA effects on sAPPα, but not Aβ, levels in primary astrocytes resembled those of ADAM10 inhibition, indicating at least partly independent trafficking pathways for sAPPα and Aβ. In conclusion, DAPG might be a promising drug candidate against AD regulating ADAM10 and intracellular trafficking, but optimizing DAPG ability to cross the BBB will be needed.

2-Mercaptobenzimidazole clubbed hydrazone for Alzheimer's therapy: In vitro, kinetic, in silico, and in vivo potentials.

Alzheimer’s is a type of dementia that affects the affected person’s thinking, memory, and behavior. It is a multifactorial disease, developed by the breakdown of the neurotransmitter acetylcholine via acetylcholinesterase (AChE). The present study was designed to evaluate potential inhibitors of acetylcholinesterase that could be used as a therapeutic agent against Alzheimer’s disease (AD). For this course, synthetic compounds of the Schiff bases class of 2-mercaptobenzimidazole hydrazone derivatives (9–14) were determined to be potent acetylcholinesterase inhibitors with IC50 values varying between 37.64 ± 0.2 and 74.76 ± 0.3 μM. The kinetic studies showed that these are non-competitive inhibitors of AChE. Molecular docking studies revealed that all compounds accommodate well in the active site and are stabilized by hydrophobic interactions and hydrogen bonding. Molecular dynamics (MD) simulations of selected potent inhibitors confirm their stability in the active site of the enzyme. Moreover, all compounds showed antispasmodic and Ca2+ antagonistic activities. Among the selected compounds of 2-mercaptobenzimidazole hydrazone derivatives, compound 11 exhibited the highest activity on spontaneous and K+-induced contractions, followed by compound 13. Therefore, the Ca2+ antagonistic, AChE inhibition potential, and safety profile of these compounds in the human neutrophil viability assay make them potential drug candidates against AD in the future.

Computational prediction of potential drug-like compounds from Cannabis sativa leaf extracts targeted towards Alzheimer therapy

• Phytochemicals isolated from Cannabis sativa can improve behavioral symptoms associated with neurological diseases including AD. • Morphinan-6-one demonstrated inhibitory actions against AChE and DDC, suggesting that it might have dual functions in AD. • Morphinan-6-one is hypothesized to be a modulatory molecule for acetylcholinesterase. This study was aimed at evaluating the inhibitory effects of the phytochemicals from the Cannabis sativa (Cannabis) leaf extracts against Alzheimer’s disease (AD) protein targets. Twelve compounds derived from the Cannabis sativa leaf extracts were evaluated as potential inhibitors of acetylcholinesterase (AChE), dopa decarboxylase (DDC), serotonin receptor 2C (HTR2C) and monoamine oxidase (MAO). Ligand-based and receptor-ligand complex were used to derive the pharmacophore hypothesis. In silico study through molecular docking simulation method was adopted to analyze the inhibitory activity of the compounds in question. Molecular dynamic simulation (MDs) was performed to assess the stability of the top-ranked phytochemicals. The binding energies of these compounds to the four targets were investigated by the Molecular Mechanics for the Generalized Born Model and Solvent Accessibility method (MM-GBSA). The binding-free energy suggests that cannabinol, cannabichromene, linoelaidic acid and morphinan-6-one can be utilized as lead compounds in drug discovery and development of AD to inhibit activity of AChE, DCC gene, MAO and HTR2C. The MDs indicated that AChE-Cannabinol, DCC-Cannabicoumaronone, MAO-Linoelaidic acid, and HTR2C-morphinan-6-one were stable over the entire course of 100 ns suggesting their role in the regulation of the diseases in which their respective receptors are implicated.

Synthesis and biological evaluation of 4-hydroxy-methylpiperidinyl-N-benzyl-acylarylhydrazone hybrids designed as novel multifunctional drug candidates for Alzheimer’s disease

The search for new drug candidates against Alzheimer’s disease (AD) remains a complex challenge for medicinal chemists due to its multifactorial pathogenesis and incompletely understood physiopathology. In this context, we have explored the molecular hybridization of pharmacophore structural fragments from known bioactive molecules, aiming to obtain a novel molecular architecture in new chemical entities capable of concomitantly interacting with multiple targets in a so-called multi-target directed ligands (MTDLs) approach. This work describes the synthesis of 4-hydroxymethyl)piperidine-N-benzyl-acyl-hydrazone derivatives 5a-l, designed as novel MTDLs, showing improved multifunctional properties compared to the previously reported parent series of N-benzyl-(3-hydroxy)piperidine-acyl-hydrazone derivatives 4. The new improved derivatives were studied in silico, regarding their mode of interaction with AChE enzyme, and in vitro, for evaluation of their effects on the selective inhibition of cholinesterases, cellular antioxidant, and neuroprotective activities as their cytotoxicity in human neuroblastoma (SH-SY5Y) cells. Overall, compound PQM-181 (5 k) showed the best balanced selective and non-competitive inhibition of AChE (IC50 = 5.9 μM, SI > 5.1), with an additional antioxidant activity (IC50 = 7.45 µM) against neuronal t-BOOH-induced oxidative stress and neuroprotective ability against neurotoxicity elicited by both t-BOOH and OAβ1-42, and a moderate ability to interfere in Aβ1-42 aggregates, with low cytotoxicity and good predictive druggability properties, suggesting a multifunctional pharmacological profile suitable for further drug development against AD.

Jatamansinol from Nardostachys jatamansi Ameliorates Tau-Induced Neurotoxicity in Drosophila Alzheimer's Disease Model.

Nardostachys jatamansi has long been used to prepare Medhya Rasayana in traditional Indian Ayurveda medicine to treat neurological disorders and enhance memory. Jatamansinol from the N. jatamansi against Alzheimer's disease (AD) showed that it could be a multitargeted drug against AD. Drosophila is an ideal model organism for studying a progressive age-related neurodegenerative disease such as AD since its neuronal organizations and functioning are highly similar to that of humans. The current study investigates the neuroprotective properties of jatamansinol against Tau-induced neurotoxicity in the AD Drosophila model. Results indicate jatamansinol is not an antifeedant for larva and adult Drosophila. Lifespan, locomotor activity, learning and memory, Tau protein expression level, eye degeneration, oxidative stress level, and cholinesterase activities were analyzed in 10, 20, and 30-day-old control (wild type), and tauopathy flies reared on jatamansinol supplemented food or regular food without jatamansinol supplementation. Jatamansinol treatment significantly extends the lifespan, improves locomotor activity, enhances learning and memory, and reduces Tau protein levels in tauopathy flies. It boosts the antioxidant enzyme activities, prevents Tau-induced oxidative stress, ameliorates eye degeneration, and inhibits cholinesterase activities in Tau-induced AD model. This study provides the first evidence that jatamansinol protects against Tau's neurotoxic effect in the AD Drosophila model, and it can be a potential therapeutic drug candidate for AD.

N-Substituted Arylidene-3-(Methylsulfonyl)-2-Oxoimidazolidine-1-Carbohydrazide as Cholinesterase Inhibitors: Design, Synthesis, and Molecular Docking Study.

The development of new enzyme inhibitors in degenerative brain diseases has gained more attention. Enzyme inhibitors play an effective role in controlling central nervous system diseases. For this purpose, a novel series of hydrazone derivatives containing imidazolidine ring aimed against Alzheimer's disease (AD), have been designed and synthesized. The acetylcholinesterase (AChE) enzyme inhibitory activity of these compounds was investigated. The structures of the compounds were determined by IR, 1 H and 13 C-NMR and mass spectroscopic methods. Inhibition studies on the cholinesterase (ChE) enzymes and β-amyloid plaque inhibition test of the compounds were performed. Based on the experimental results, compound 3j bearing dimethoxy substituent on the aromatic ring like donepezil exhibited the most AChE inhibitory activity with the IC50 values of 0.023±0.001 μM. Owing to obtained biological activity and molecular docking study results, it is thought that the most active compound 3j may play a role in both symptomatic and palliative treatment of AD.

Contribution to Pharmacological Valorisation of Algerian Arctium minus (Hill) Bernh. Subsp. Atlanticum (Pomel) Maire; Antioxidant an d Acetylcholinesterase Inhibitory Activities

Background: The traditional pharmacopoeia is full of potential resources for molecules with therapeutic effects involving the inhibition of enzymes linked to some diseases. Objective: This work aimed to test in vitro neuroprotective activity against Alzheimer's disease (AD) combined with the antioxidant effect of root extracts obtained by water, water/methanol, and ethyl acetate of the endemic Arctium minus. subsp. Atlanticum, a native of Algeria. Methods: The different extracts of the root of the studied plant were obtained by decoction or maceration. The inhibitory effect of acetyl/butyrylcholinesterase (AChE/BChE) was achieved by a colorimetric method. Similarly, the antioxidant activity was measured based on several mechanisms: 1, 1- diphenyl-2-picryl-hydrazyl (DPPH) and galvinoxyl (GOR) radicals free scavenging assays, β-carotene bleaching inhibition activity, and cupric ion reducing antioxidant capacity (CUPRAC). Results: In the various tests carried out, the ethyl acetate extract (EAE) possessed the most powerful antioxidant and anticholinesterase activities compared to the other samples. The IC50 and A0.5 values of DPPH, GOR, β-carotene, CUPRAC, anti-AChE, and anti-BChE assays were 69.45±5.49, 28.87±0.18, 121.58±16.76, 37.41±1.59, 265±21, and 240±6.3 μg / mL, respectively. Likewise, a correlation could be deduced between the type of extract and the potent antioxidant/anticholinesterase potential. Conclusion: This work examines for the first time the anticholinesterase potential combined with the antioxidant effect of Algerian Arctium minus. subsp. atlanticum. This association between the two effects could be effective in the fight against AD, and therefore, the use of this natural resource may be possible in combating this aspect of neurodegeneration.

An Overview of Tetramethylpyrazine (Ligustrazine) and its Derivatives as Potent Anti-Alzheimer’s Disease Agents

Abstract:Tetramethylpyrazine (TMP), or ligustrazine, is an alkaloid isolated from the Chinese herb Ligusticum wallichii. It is known for its broad-spectrum medicinal properties against several diseases, and various studies have shown that it can modulate diverse biological targets and signaling pathways to produce neuroprotective effects, especially against Alzheimer’s disease (AD). This has attracted significant research attention evaluating TMP as a potent multitarget anti-AD agent. This review compiles the results of studies assessing the neuroprotective mechanisms exerted by TMP as well as its derivatives prepared using a multi-target-directed ligand strategy to explore its multitarget modulating properties. The present review also highlights the work done on the design, synthesis, structure-activity relationships, and mechanisms of some potent TMP derivatives that have shown promising anti-AD activities. These derivatives were designed, synthesized, and evaluated to develop anti-AD molecules with enhanced biological and pharmacokinetic activities compared to TMP. This review article paves the way for the exploration and development of TMP and TMP derivatives as an effective treatment for AD.

Protective Effects of Isothiocyanates against Alzheimer's Disease

Background: The extensive search for a novel therapeutic agent against Alzheimer's Disease (AD) in medical and pharmaceutical research still continues. Despite a lot being explored about its therapeutics, there is still much more to learn in order to achieve promising therapeutic agents against AD. Phytochemicals, especially secondary metabolites, are the major focus of the investigators for AD treatment. Objective: To describe major therapeutics targets of AD and the role of isothiocyanates (ITCs) in modulating these targets. Methods: Scientific databases, including Elsevier, Science Direct, Pub med, were explored. The explored literature was mainly journal publications on pathogenesis and targets of AD, and the effect of various ITCs in the modulation of these targets. Results: The major targets of AD include the Nrf-2/ARE signaling pathway, MAPKs pathway, GSK-3 signaling, and Ubiquitin-Protease system. ITCs, such as Sulforaphane, Allyl isothiocyanates, Moringin, 6-(methylsulfinyl) hexyl ITC, Phenethyl isothiocyanates, and Erucin, were reported to exert a protective effect against AD via modulating one of the several above mentioned targets. Conclusion: This article gives a detailed description of the therapeutic targets of AD and sheds light that phytochemicals, such as ITCs, can exert a protective effect against AD by targeting those pathways. However, properly designed research and clinical trials are required to include ITCs as a mainstream agent against AD.

Coagulansin-A improves spatial memory in 5xFAD Tg mice by targeting Nrf-2/NF-κB and Bcl-2 pathway

The present study was designed to investigate the underlying molecular signaling of Coagulansin-A (Coag-A) as a therapeutic agent against Alzheimer’s disease (AD). Preliminarily, it exhibited a neuroprotective effect against H2O2-induced oxidative stress in HT-22 cells. The in vivo studies were performed by administering Coag-A (0.1, 1, and 10 mg/kg) intraperitoneally to 5xFAD transgenic (Tg) mouse model. Coag-A (10 mg/kg) significantly attenuated the cognitive decline compared to Tg mice group in the shallow water maze (SWM) and Y-maze test paradigms. The anti-aggregation potential of Coag-A was determined by performing Fourier transform-infrared (FT-IR) spectroscopy and differential scanning calorimeter (DSC) analysis in the prefrontal cortex (PFC) and hippocampal (HC) regions of mice brain. The FT-IR spectra demonstrated the inhibition of amyloid beta (Aβ) through a decrease in β-sheet aggregation, along with the inhibition of changes in the lipids, proteins, and phospholipids. The DSC analysis displayed a low-temperature exotherm associated with the reversible process of aggregation of soluble protein fractions prior to denaturation. Furthermore, Coag-A treatment displayed a regular density of granule cells in H&E stained sections, along with a reduced amyloid load and PAS-positive granules in all the regions of interest in mice brain. The real-time polymerase chain reaction (q-PCR), western blot and immunohistochemical (IHC) analysis demonstrated antioxidant, anti-inflammatory, and anti-apoptotic effect of Coag-A by enhancing the expression of nuclear factor erythroid-2-related factor (Nrf-2) and reducing nuclear factor kappa B (NF-κB) and Bax protein expression. In addition, Coag-A significantly increased the antioxidant enzymes and proteins level, along with a reduced pro-inflammatory cytokines production.

Synthesis and Evaluation of Novel Ferulic Amide Derivatives and the Treatment of Alzheimer's Disease

AbstractSixteen ferulic amide (FA) derivatives were designed, synthesized and evaluated as multi‐target inhibitors against Alzheimer's disease (AD). In vitro studies indicated that most of the compounds showed significant potency to inhibit acetylcholinesterase (AChE) and self‐induced β‐amyloid (Aβ) aggregation. Specifically, a dimeric FA analogue with a diamide linker (compound 4 c) exhibited the potent ability to inhibit AChE (IC50, 0.35 μM) and the good Aβ aggregation inhibition (46.6 % at 20 μM). The structure‐activity relationships were also discussed as well as their binding conformation and simultaneous interactions mode were further clarified by the molecular docking studies. Moreover, it also produced good effects against scopolamine‐induced cognitive impairment in vivo. These results suggested that compound 4 c was a promising drug candidate against AD.

Treadmill Exercise Promotes Microglial β-Amyloid Clearance and Prevents Cognitive Decline in APP/PS1 Mice

Growing evidence has demonstrated that treadmill exercise is beneficial to increase β-amyloid (Aβ) clearance and protect against Alzheimer’s disease (AD). However, the underlying mechanisms remain to be elucidated. Recently, microglia dysfunction leading to Aβ clearance impairment is proved an important mechanism for later Aβ deposition and AD pathogenesis. The present study aimed to confirm the effect of exercise on Aβ deposition and to investigate the role of microglia in exercise-induced Aβ reduction. In the present study, 3-month-old male APPswe/PS1dE9 (APP/PS1) mice and C57BL/6 wild-type mice were randomly divided into sedentary (SED) or exercise (EX) group, twelve mice in each group. Mice in exercise groups were subjected to ran on a treadmill for 3 months, 5 days/week. Afterwards, the spatial learning and memory, hippocampal fibrillar Aβ deposits and microglial functions were determined by Morris water maze task, methoxy-X04 staining as well as in vivo and in vitro assays, respectively. The results showed that 3 months of treadmill exercise largely prevented spatial learning and memory decline and alleviated hippocampal methoxy-X04-positive fibrillar Aβ deposits in APP/PS1 mice. Moreover, treadmill exercise partly restored microglial Aβ degradation and clearance in the hippocampus, which was impaired in APP/PS1 mice. However, the impaired microglial Aβ phagocytosis in APP/PS1 mice was not altered after 3 months of treadmill exercise intervention. These findings demonstrate that 3 months of treadmill exercise alleviates hippocampal Aβ deposition and restores spatial learning and memory in APP/PS1 mice, partly by promoting microglial Aβ degradation and clearance.

Discovery of New 1,3,4-Oxadiazoles with Dual Activity Targeting the Cholinergic Pathway as Effective Anti-Alzheimer Agents.

Finding an effective anti-Alzheimer agent is quite challenging due to its multifactorial nature. As such, multitarget directed ligands (MTDLs) could be a promising paradigm for finding potential therapeutically effective new small-molecule bioactive agents against Alzheimer's disease (AD). We herein present the design, synthesis, and biological evaluation of a new series of compounds based on a 5-pyrid-3-yl-1,3,4-oxadiazole scaffold. Our synthesized compounds displayed excellent in vitro enzyme inhibitory activity at nanomolar (nM) concentrations against two major AD disease-modifying targets, i.e., acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Among our compounds, 5e was considered the best dual inhibitor of both AChE (IC50 = 50.87 nM) and BuChE (IC50 = 4.77 nM), where these values surpassed those of rivastagmine (the only FDA-approved dual AChE and BuChE inhibitor) in our study. Furthermore, in vivo and ex vivo testing of the hit compound 5e highlighted its significant AD-biotargeting effects including reducing the elevated levels of lipid peroxidation and glutathione (GSH), normalizing levels of 8-OHdG, and, most importantly, decreasing the levels of the well-known AD hallmark β-amyloid protein. Finally, the binding ability of 5e to each of our targets, AChE and BuChE, was confirmed through additional molecular docking and molecular dynamics (MD) simulations that reflected good interactions of 5e to the active site of both targets. Hence, we herein present a series of new 1,3,4-oxadiazoles that are promising leads for the development of dual-acting AChE and BuChE inhibitors for the management of AD.

A Neuropsychological Perspective on Defining Cognitive Impairment in the Clinical Study of Alzheimer's Disease: Towards a More Continuous Approach.

The global fight against Alzheimer's disease (AD) poses unique challenges for the field of neuropsychology. Along with the increased focus on early detection of AD pathophysiology, characterizing the earliest clinical stage of the disease has become a priority. We believe this is an important time for neuropsychology to consider how our approach to the characterization of cognitive impairment can be improved to detect subtle cognitive changes during early-stage AD. The present article aims to provide a critical examination of how we define and measure cognitive status in the context of aging and AD. First, we discuss pitfalls of current methods for defining cognitive impairment within the context of research shifting to earlier (pre)symptomatic disease stages. Next, we introduce a shift towards a more continuous approach for identifying early markers of cognitive decline and characterizing progression and discuss how this may be facilitated by novel assessment approaches. Finally, we summarize potential implications and challenges of characterizing cognitive status using a continuous approach.

In Silico Studies on the Phytochemicals from Aframomum melegueta Leaves against Key Enzymes as Anti-Alzheimer’s Disease Target

Traditional medicine has been practiced for ages across the world using plants as a memory booster and in the treatment of neurodegenerative diseases such as dementia and amnesia. The tau, amyloid hypothesis and neuroinflammation hypothesis are major partakers in a combinational approach in the development of therapy against Alzheimer’s disease (AD), Acetyl and butyryl cholinesterases inhibitors have been investigated in clinical trials of AD for a very long time. This research involved an in-silico approach to study the interactions of phytochemicals in Aframomum melegueta leaves with some enzymes that have been reported in the literature which contribute to neuronal death and memory loss associated in AD. In these studies, Curcumin and Lilacin are shown to have a higher glide score than the co-crystallized ligands of either Acetylcholinesterase, Butyrylcholinesterase or GSK-3β, they also have higher glide scores than AChE inhibitor Rivastigmine. The ADMET/tox properties of our lead compounds (curcumin and lilacin) ranked them as good candidates for AD drug development, as well as possess the highest docking scores against acetylcholinesterase, butyrylcholinesterase and GSK-3 beta suggesting potent compounds in Alzheimer’s disease therapy. The pharmacokinetics studies also showed that curcumin and lilacin would pass through the blood brain barrier into the brain. This work is in line with recent multi-dimensional approach in drug development in that a single compound might possess many active groups which can activate/inhibit more than one protein without any toxic effect.

Donepezil-Inspired Multitargeting Indanone Derivatives as Effective Anti-Alzheimer's Agents.

In continuous efforts to develop anti-Alzheimer's agents, we rationally designed and synthesized a series of multitargeting molecules by incorporating the essential molecular features of the standard drug donepezil. Among the series, compound 4b showed multitargeting properties to act as an anti-Alzheimer's agent, which is better tolerable in vivo than donepezil. Acetylcholinesterase (AChE) inhibition data showed that compound 4b inhibits the enzyme with a half-maximal inhibitory concentration (IC50) value of 0.78 μM and also showed DNA protection, which was confirmed through the DNA nicking assay, suggesting the protective effect of 4b against oxidative DNA damage. Compound 4b also showed 53.04% inhibition against Aβ1-42 aggregations, which was found comparable to that of the standard compound curcumin. Molecular dynamics simulations were performed to check the stability of compound 4b with the enzyme AChE, which showed that the enzyme-ligand complex is stable enough to block the hydrolysis of acetylcholine in the brain. Its higher LD50 cutoff value (50 mg/kg) in comparison to donepezil (LD50: 25 mg/kg) made it safer, suggesting that it can be used in further clinical experiments. To evaluate its anti-Alzheimer property, a mice model with melamine-induced cognitive dysfunction was used, and Morris water maze and Rotarod tests were performed. A significant improvement in memory was observed after the treatment with compound 4b and donepezil. The study postulated that the introduction of important structural features of donepezil (dimethoxyindanone moiety as ring-A) embarked with terminal aromatic ether (ring-B and ring-C) made 4b a multitargeting molecule that offers a way for developing alternative therapeutics in the future against Alzheimer's disease (AD).

1-(7-Chloroquinolin-4-yl)-N-(4-Methoxybenzyl)-5-Methyl-1H-1,2, 3-Triazole-4- carboxamide Reduces Aβ Formation and Tau Phosphorylation in Cellular Models of Alzheimer's Disease.

1-(7-Chloroquinolin-4-yl)-N-(4-methoxybenzyl)-5-methyl-1H-1,2,3-triazole-4- carboxamide (QTC-4-MeOBnE) is a new multi-target directed ligand (MTDL) rationally designed to have affinity with β-secretase (BACE), Glycogen Synthase Kinase 3β (GSK3β) and acetylcholinesterase, which are considered promising targets on the development of disease-modifying therapies against Alzheimer's Disease (AD). Previously, QTC-4-MeOBnE treatment showed beneficial effects in preclinical AD-like models by influencing in vivo neurogenesis, oxidative and inflammatory pathways. However, the biological effect and mechanism of action exerted by QTC-4-MeOBnE in AD cellular models have not been elucidated yet. Hereby we investigate the acute effect of QTC-4-MeOBnE on neuronal cells overexpressing Amyloid Protein Precursor (APP) or human tau protein, the two main features of the AD pathophysiology. When compared to the control group, QTC-4-MeOBnE treatment prevented amyloid beta (Aβ) formation through the downregulation of APP and BACE levels in APPswe-expressing cells. Furthermore, in N2a cells overexpressing human tau, QTC-4-MeOBnE reduced the levels of phosphorylated forms of tau via the modulation of the GSK3β pathway. Taken together, our findings provide new insights into the mechanism of action exerted by QTC-4-MeOBnE in AD cellular models, and further support its potential as an interesting therapeutic strategy against AD.

Protein phosphatase 2A and complement component 4 are linked to the protective effect of APOE ɛ2 for Alzheimer's disease.

The apolipoprotein E (APOE) ɛ2allele reduces risk against Alzheimer's disease (AD) but mechanisms underlying this effect are largely unknown. We conducted a genome-wide association study for AD among 2096 ɛ2 carriers. The potential role of the top-ranked gene and complement 4 (C4) proteins, which were previously linked to AD in ɛ2 carriers, was investigated using human isogenic APOE allele-specific induced pluripotent stem cell (iPSC)-derived neurons and astrocytes and in 224 neuropathologically examined human brains. PPP2CB rs117296832 was the second most significantly associated single nucleotide polymorphism among ɛ2 carriers (P=1.1×10-7 ) and the AD risk allele increased PPP2CB expression in blood (P=6.6×10-27 ). PPP2CB expression was correlated with phosphorylated tau231/total tau ratio (P=.01) and expression of C4 protein subunits C4A/B (P=2.0×10-4 ) in the iPSCs. PPP2CB (subunit of protein phosphatase 2A) and C4b protein levels were correlated in brain (P=3.3×10-7 ). PP2A may be linked to classical complement activation leading to AD-related tau pathology.

Can We Use Ginkgo biloba Extract to Treat Alzheimer's Disease? Lessons from Preclinical and Clinical Studies.

(1) Background: Ginkgo biloba extract (GBE) has been widely used to treat central nervous system and cardiovascular diseases. Accumulating evidence has revealed the therapeutic potential of GBE against Alzheimer's disease (AD); however, no systematic evaluation has been performed; (2) Methods: a total of 17 preclinical studies and 20 clinical trials assessing the therapeutic effects of GBE against AD were identified from electronic databases. The data in the reports were extracted to conduct a meta-analysis of the AD-related pathological features or symptoms; (3) Results: For the preclinical reports, 45 animals treated with GBE, in six studies, were subjected to cognitive function assessments by the Morris water maze. GBE was shown to reduce the escape latencies in several studies, in both rats and mice (I2 > 70%, p < 0.005). For the clinical trials, eight trials, including 2100 individuals, were conducted. The results show that GBE improved the SKT and ADAS-Cog scores in early-stage AD patients after high doses and long-term administration; (4) Conclusions: GBE displayed generally consistent anti-AD effects in animal experiments, and it might improve AD symptoms in early-stage AD patients after high doses and long-term administration. A lack of sample size calculations and the poor quality of the methods are two obvious limitations of the studies. Nevertheless, the preclinical and clinical data suggest that further large-scale clinical trials may be needed in order to examine the effects of long-term GEB administration on early-stage AD.