Recent advances in the neurobiology and neuropharmacology of Alzheimer’s disease

Computational insights in repurposing a cardiovascular drug for Alzheimer's disease: the role of aromatic amino acids in stabilizing the drug through π-π stacking interaction

Alzheimer's disease (AD) is a neurological condition that worsens over time and causes linguistic difficulties, cognitive decline, and memory loss. Since AD is a complicated, multifaceted illness, it is critical to identify drugs to combat this degenerative condition. Histone deacetylase 2 (HDAC2) represents a promising epigenetic target for neurodegenerative diseases. So, for this study, we chose HDAC2 as the targeted protein. Repurposing drugs has many advantages, including reduced costs and high profits. There is a lower probability of malfunction because the unique drug candidate has previously completed numerous investigations. In this study, we have taken 58 clinically approved food and drug administration (FDA) drugs utilized in clinical trials for AD. Molecular docking was carried out for the 58 compounds. The telmisartan drug has the highest binding score of -9.4 kcal mol-1. The angiotensin II receptor blocker (ARB) telmisartan has demonstrated some promise in AD research as of the last update in January 2022. However, its exact significance in treating or preventing AD is still being studied. Molecular dynamics (MD) and molecular mechanics with generalized born and surface area solvation (MM-GBSA)/interaction entropy (IE) calculations were carried out to study the structural stability of the complexes. Umbrella sampling (US) techniques are a cutting-edge drug development method to understand more about the interactions between protein and ligand. π-π stacking interactions play a major role in helping the ligand to bind in the zinc bounding domain of the protein. From these analyses, we conclude that telmisartan, which is a cardiovascular drug, is more potent than the other drugs to treat AD. The anti-inflammatory, neuroprotective, and blood-brain barrier-crossing qualities of telmisartan make it a promising therapeutic agent for AD; however, more research, including larger clinical trials, is needed to determine the drug's precise role in treating AD.

Neuroprotective properties of a thiazolidine-2,4-dione derivative as an inhibitory agent against memory impairment and phosphorylated tau: In vitro and in vivo investigations

Alzheimer's disease (AD) is the most common form of neurodegeneration that results in memory disorders and cognitive impairment. The present study investigated the neuroprotective effects of the synthesized thiazolidine-2,4-dione derivative, (E)-5-(4-chlorobenzylidene)-3-(2-oxo-2-phenylethyl)thiazolidine-2,4-dione (TZ4C), an inhibitor of p-Tau and memory impairment, using a SH-SY5Y cell model of methamphetamine-induced tauopathy and a scopolamine-induced memory impairment model in Wistar rats. In the present study, the neuroprotective effect of TZ4C was studied in a SH-SY5Y cellular model of methamphetamine-induced (2 mM) tauopathy and a scopolamine-induced (1.5 mg/kg/day) memory impairment model in male Wistar rats (n = 48). The memory functions and learning abilities of the rats were evaluated using the Morris water maze (MWM) and passive avoidance tests. Additionally, AChE activity in the rat hippocampus was quantified, and the expression of p-Tau, HSP70, and caspase-3 in both in vitro and in vivo samples was evaluated through Western blot analysis. TZ4C (0.1-1000 µM) did not exhibit significantly toxic effects on SH-SY5Y cell viability. Western blot results indicated that TZ4C led to reduced expression of p-Tau, HSP70, and cleaved caspase-3 in SH-SY5Y cells (3 and 10 µM) and the rat hippocampus (2 and 4 mg/kg). Additionally, the findings suggested that TZ4C enhanced memory function in rats with scopolamine-induced impairment and decreased acetylcholinesterase (AChE) specific activity. The comprehensive analysis of in vitro and in vivo experiments underscores the neuroprotective potential (improved neuropathology and reduced memory impairment) of TZ4C. These findings highlight the promise of TZ4C as a candidate for drug discovery programs to identify effective therapies for AD.

Inflammatory signaling pathways in Alzheimer's disease: Mechanistic insights and possible therapeutic interventions

The complex pathophysiology of Alzheimer's disease (AD) poses challenges for the development of therapies. Recently, neuroinflammation has been identified as a key pathogenic mechanism underlying AD, while inflammation has emerged as a possible target for the management and prevention of AD. Several prior studies have demonstrated that medications modulating neuroinflammation might lessen AD symptoms, mostly by controlling neuroinflammatory signaling pathways such as the NF-κB, MAPK, NLRP3, etc, and their respective signaling cascade. Moreover, targeting these inflammatory modalities with inhibitors, natural products, and metabolites has been the subject of intensive research because of their anti-inflammatory characteristics, with many studies demonstrating noteworthy pharmacological capabilities and potential clinical applications. Therefore, targeting inflammation is considered a promising strategy for treating AD. This review comprehensively elucidates the neuroinflammatory mechanisms underlying AD progression and the beneficial effects of inhibitors, natural products, and metabolites in AD treatment.

Exploring new 5-Nitroimidazole Derivatives as Potent Acetylcholinesterase and Butyrylcholinesterase Enzyme Inhibitors

Discovering new compounds capable of inhibiting physiologically and metabolically significant drug targets or enzymes is of paramount importance in biological chemistry. With this aim, new 5-nitroimidazole derivatives (1-4) were designed and synthesized, and their inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were discovered using acetyl (butyryl) thiocholine and Ellman's reagents for spectrophotometric assay. The inhibitory profiles of the synthesized compounds were assessed by comparing their IC50 and Ki values. Results demonstrate significant inhibitory activity of all synthesized compounds against both AChE and BuChE compared to the reference compound, donepezil. Notably, compound 4 exhibited dual inhibition of these enzymes, showing the highest activity against Electrophorus electricus AChE (EeAChE) with a Ki value of 0.024±0.009 nM and against equine BuChE (eqBuChE) with a Ki value of 0.087±0.017 nM. Furthermore, molecular modeling was conducted to study the interaction modes of the most potent compound (4) and donepezil in the active site of their related enzymes' crystal structures (PDB ID: 4EY7 and 4BDS, respectively). Additionally, drug-likeness, ADME, and toxicity profiles of the compounds and metronidazole were predicted. The above results indicated that the dual inhibition of these enzymes is considered as a promising strategy for the treatment of neurological disorder especially Alzheimer's disease.

The Effect of Bone Marrow Mesenchymal Stem Cells on Nestin and Sox-2 Gene Expression and Spatial Learning (Percent Alternation Y-Maze Test) against AlCl3-Induced Alzheimer's-like Pathology in a Rat Model

Background

Alzheimer's disease (AD) is a neurodegenerative condition characterized by gradual cognitive impairment, including loss of synapses and nerve cells involved in learning, memory, and habit formation processes. Bone Marrow Mesenchymal Stem Cells (BM-MSCs) are multipotent cells. Because of their self-renewable, differentiation, and immunomodulatory capabilities, they are commonly used to treat many disorders. Hence, the current study intends to examine the effect of BM-MSCs transplantation on Aluminum chloride (AlCl3)-induced cognitive problems, an experimental model resembling AD's hallmarks in rats.

Methods

The study was conducted in 2022 at The Biomedical Laboratory Faculty of Medicine, Andalas University, Indonesia. Adult male Wistar rats (three groups: negative control; no intervention+treatment with PBS; positive control: AlCl3+treatment with aqua dest; AlCl3+BM-MSCs: AlCl3+treatment with BM-MSCs, n=5 each) were treated daily with AlCl3 orally for five days. Stem cells were intraperitoneally injected into rats at a dose of 1x106 cells/rat. The same quantity of phosphate-buffered saline was given to the control group. One month after stem cell injection, the rat brain tissue was removed and placed in the film bottles that had been created. The expression of neural progenitor cell markers, including nestin and sex-determining Y-box 2 (SOX-2), was analyzed using real-time polymerase chain reaction (RT-PCR). Rats' cognitive and functional memory were examined using Y-maze. Data were analyzed using SPSS software (version 26.0) with a one-way analysis of variance (ANOVA) test.

Results

The gene expression of nestin (29.74±0.42), SOX-2 (31.44±0.67), and percent alternation of Y-maze (67.04±2.28) increased in the AlCl3+BM-MSCs group compared to that in the positive control group. RT-PCR analysis indicated that nestin (P<0.001) and SOX-2 (P<0.001) were significantly enhanced in the AlCl3+BM-MSCs group compared to the positive control group. This group also indicated an increased percent alternation of Y-maze (P<0.001) in the AlCl3+BM-MSCs group compared to the positive control group.

Conclusion

Due to its potential effects on cell therapy, BM-MSCs were found effective in a rat model of AD on the impairment of the rats' behavior and increased expression of neural progenitor cell markers.

Combined transcriptome and widely targeted metabolome analysis reveals the potential mechanism of HupA biosynthesis and antioxidant activity in Huperzia serrata

Introduction

Huperzia serrata is a traditional Chinese herb that has gained much attention for its production of Huperzine A (HupA). HupA has shown promise on treating Alzheimer's disease (AD). However, the biosynthetic pathway and molecular mechanism of HupA in H. serrata are still not well understood.

Methods

Integrated transcriptome and metabolome analysis was performed to reveal the molecular mechanisms related to HupA biosynthesis and antioxidant activity in Huperzia serrata.

Results

HT (in vitro H. serrata thallus) exhibits higher antioxidant activity and lower cytotoxicity than WH (wild H. serrata). Through hierarchical clustering analysis and qRT-PCR verification, 7 important enzyme genes and 13 transcription factors (TFs) related to HupA biosynthesis were detected. Among them, the average |log2FC| value of CYP (Cytochrome P450) and CAO (Copper amine oxidase) was the largest. Metabolomic analysis identified 12 metabolites involved in the HupA biosynthesis and 29 metabolites related to antioxidant activity. KEGG co-enrichment analysis revealed that tropane, piperidine and pyridine alkaloid biosynthesis were involved in the HupA biosynthesis pathway. Furthermore, the phenylpropanoid, phenylalanine, and flavonoid biosynthesis pathway were found to regulate the antioxidant activity of H. serrata. The study also identified seven important genes related to the regulation of antioxidant activity, including PrAO (primary-amine oxidase). Based on the above joint analysis, the biosynthetic pathway of HupA and potential mechanisms of antioxidant in H. serrata was constructed.

Discussion

Through differential transcriptome and metabolome analysis, DEGs and DAMs involved in HupA biosynthesis and antioxidant-related were identified, and the potential metabolic pathway related to HupA biosynthesis and antioxidant in Huperzia serrata were constructed. This study would provide valuable insights into the HupA biosynthesis mechanism and the H. serrata thallus medicinal value.

Factors associated with cognitive function in patient with Alzheimer's disease with newly prescribed acetylcholinesterase inhibitors: A 1-year retrospective cohort study

Objective

We aimed to examine the factors associated with treatment outcomes in patients with Alzheimer's disease (AD) after 1 year of acetylcholinesterase inhibitors (AChEI) treatment.

Method

We obtained electronic medical records from a medical center in Southern Taiwan between January 2015 and September 2021. Participants aged ≥60 who were newly diagnosed with AD and had been prescribed AChEIs were included. Cognitive assessments were performed before the AChEIs were prescribed and at the 1 year follow-up. Cognition progressors were defined as a Mini-Mental State Examination decline of >3 or a Clinical Dementia Rating decline of ≥1 after 1 year of AChEI treatment. The relationship between the baseline characteristics and cognitive status after follow-up was investigated using logistic regression analysis after adjusting for potential confounders.

Results

A total of 1370 patients were included in our study (mean age, 79.86 ± 8.14 years). After adjustment, the body mass index (BMI) was found to be significantly lower in the progressor group [adjusted odds ratio (AOR): 0.970, 95% confidence intervals (95% CIs): 0.943 to 0.997, P = 0.033]. The usage of antipsychotics was significantly higher in the progressor group (AOR: 1.599, 95% CIs: 1.202 to 2.202, P = 0.001). The usage of benzodiazepine receptor agonists also tended to be significantly higher in the progressor group (AOR: 1.290, 95% CIs: 0.996 to 1.697, p = 0.054).

Conclusion

These results suggest that patients with AD who receive 1 year of AChEI treatment and have a lower BMI or concurrent treatment with antipsychotics and benzodiazepine receptor agonists are more likely to suffer from cognitive decline.

Discovery of novel quinolin-2-one derivatives as potential GSK-3β inhibitors for treatment of Alzheimer's disease: Pharmacophore-based design, preliminary SAR, in vitro and in vivo biological evaluation

Recently, glycogen synthase kinase-3β (GSK-3β) has been considered as a critical factor implicated in Alzheimer's disease (AD). In a previous work, a 3D pharmacophore model for GSK-3β inhibitors was created and the results suggested that derivative ZINC67773573, VIII, may provide a promising lead for developing novel GSK-3β inhibitors for the AD's treatment. Consequently, in this work, novel series of quinolin-2-one derivatives were synthesized and assessed for their GSK-3β inhibitory properties. In vitro screening identified three compounds: 7c, 7e and 7f as promising GSK-3β inhibitors. Compounds 7c, 7e and 7f were found to exhibit superior inhibitory effect on GSK-3β with IC50 value ranges between 4.68 ± 0.59 to 8.27 ± 0.60 nM compared to that of staurosporine (IC50 = 6.12 ± 0.74 nM). Considerably, compounds 7c, 7e and 7f effectively lowered tau hyperphosphorylated aggregates and proving their safety towards the SH-SY5Y and THLE2 normal cell lines. The most promising compound 7c alleviated cognitive impairments in the scopolamine-induced model in mice. Compound 7c's activity profile, while not highly selective, may provide a starting point and valuable insights into the design of multi-target inhibitors. According to the ADME prediction results, compounds 7c, 7e and 7f followed Lipinski's rule of five and could almost permeate through the BBB. Molecular docking simulations showed that these compounds are well accommodated in the ATP binding site interacting by its quinoline-2-one ring through hydrogen bonding with the key amino acids Asp133 and Val135 at the hinge region. The findings of this study suggested that these new compounds may have potential as anti-AD drugs targeting GSK-3β.

Exploring Four Atraphaxis Species: Traditional Medicinal Uses, Phytochemistry, and Pharmacological Activities

Atraphaxis is a genus of flowering plants in the family Polygonaceae, with approximately 60 species. Species of Atraphaxis are much-branched woody plants, forming shrubs or shrubby tufts, primarily inhabiting arid zones across the temperate steppe and desert regions of Central Asia, America, and Australia. Atraphaxis species have been used by diverse groups of people all over the world for the treatment of various diseases. However, their biologically active compounds with therapeutic properties have not been investigated well. Studying the biologically active components of Atraphaxis laetevirens, Atraphaxis frutescens, Atraphaxis spinosa L., and Atraphaxis pyrifolia is crucial for several reasons. Firstly, it can unveil the therapeutic potential of these plants, aiding in the development of novel medicines or natural remedies for various health conditions. Understanding their bioactive compounds enables scientists to explore their pharmacological properties, potentially leading to the discovery of new drugs or treatments. Additionally, investigating these components contributes to preserving traditional knowledge and validating the historical uses of these plants in ethnomedicine, thus supporting their conservation and sustainable utilization. These herbs have been used as an anti-inflammatory and hypertension remedies since the dawn of time. Moreover, they have been used to treat a variety of gastrointestinal disorders and problems related to skin in traditional Kazakh medicine. Hence, the genus Atraphaxis can be considered as a potential medicinal plant source that is very rich in biologically active compounds that may exhibit great pharmacological properties, such as antioxidant, antibacterial, antiulcer, hypoglycemic, wound healing, neuroprotective, antidiabetic, and so on. This study aims to provide a collection of publications on the species of Atraphaxis, along with a critical review of the literature data. This review will constitute support for further investigations on the pharmacological activity of these medicinal plant species.

Converged avenues: depression and Alzheimer's disease- shared pathophysiology and novel therapeutics

Depression, a highly prevalent disorder affecting over 280 million people worldwide, is comorbid with many neurological disorders, particularly Alzheimer's disease (AD). Depression and AD share overlapping pathophysiology, and the search for accountable biological substrates made it an essential and intriguing field of research. The paper outlines the neurobiological pathways coinciding with depression and AD, including neurotrophin signalling, the hypothalamic-pituitary-adrenal axis (HPA), cellular apoptosis, neuroinflammation, and other aetiological factors. Understanding overlapping pathways is crucial in identifying common pathophysiological substrates that can be targeted for effective management of disease state. Antidepressants, particularly monoaminergic drugs (first-line therapy), are shown to have modest or no clinical benefits. Regardless of the ineffectiveness of conventional antidepressants, these drugs remain the mainstay for treating depressive symptoms in AD. To overcome the ineffectiveness of traditional pharmacological agents in treating comorbid conditions, a novel therapeutic class has been discussed in the paper. This includes neurotransmitter modulators, glutamatergic system modulators, mitochondrial modulators, antioxidant agents, HPA axis targeted therapy, inflammatory system targeted therapy, neurogenesis targeted therapy, repurposed anti-diabetic agents, and others. The primary clinical challenge is the development of therapeutic agents and the effective diagnosis of the comorbid condition for which no specific diagnosable scale is present. Hence, introducing Artificial Intelligence (AI) into the healthcare system is revolutionary. AI implemented with interdisciplinary strategies (neuroimaging, EEG, molecular biomarkers) bound to have accurate clinical interpretation of symptoms. Moreover, AI has the potential to forecast neurodegenerative and psychiatric illness much in advance before visible/observable clinical symptoms get precipitated.

Navigating the brain: the role of exosomal shuttles in precision therapeutics

Brain diseases have become one of the leading roots of mortality and disability worldwide, contributing a significant part of the disease burden on healthcare systems. The blood-brain barrier (BBB) is a primary physical and biological obstacle that allows only small molecules to pass through it. Its selective permeability is a significant challenge in delivering therapeutics into the brain for treating brain dysfunction. It is estimated that only 2% of the new central nervous system (CNS) therapeutic compounds can cross the BBB and achieve their therapeutic targets. Scientists are exploring various approaches to develop effective cargo delivery vehicles to promote better therapeutics targeting the brain with minimal off-target side effects. Despite different synthetic carriers, one of the natural brain cargo delivery systems, "exosomes," are now employed to transport drugs through the BBB. Exosomes are naturally occurring small extracellular vesicles (EVs) with unique advantages as a therapeutic delivery system for treating brain disorders. They have beneficial innate aspects of biocompatibility, higher stability, ability to cross BBB, low cytotoxicity, low immunogenicity, homing potential, targeted delivery, and reducing off-site target effects. In this review, we will discuss the limitations of synthetic carriers and the utilization of naturally occurring exosomes as brain-targeted cargo delivery vehicles and highlight the methods for modifying exosome surfaces and drug loading into exosomes. We will also enlist neurodegenerative disorders targeted with genetically modified exosomes for their treatment.

Role of Oxidative Stress, Methionine Oxidation and Methionine Sulfoxide Reductases (MSR) in Alzheimer's Disease

A major contributor to dementia seen in aging is Alzheimer's disease (AD). Amyloid beta (Aβ), a main component of senile plaques (SPs) in AD, induces neuronal death through damage to cellular organelles and structures, caused by oxidation of important molecules such as proteins by reactive oxygen species (ROS). Hyperphosphorylation and accumulation of the protein tau in the microtubules within the brain also promote ROS production. Methionine, a residue of proteins, is particularly sensitive to oxidation by ROS. One of the enzyme systems that reverses the oxidative damage in mammalian cells is the enzyme system known as Methionine Sulfoxide Reductases (MSRs). The components of the MSR system, namely MSRA and MSRB, reduce oxidized forms of methionine (Met-(o)) in proteins back to methionine (Met). Furthermore, the MSRs scavenge ROS by allowing methionine residues in proteins to utilize their antioxidant properties. This review aims to improve the understanding of the role of the MSR system of enzymes in reducing cellular oxidative damage and AD pathogenesis, which may contribute to effective therapeutic approaches for AD by targeting the MSR system.

New insights toward molecular and nanotechnological approaches to antidiabetic agents for Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disorder affecting a major class of silver citizens. The disorder shares a mutual relationship on account of its cellular and molecular pathophysiology with type-II diabetes mellitus (DM). Chronic DM increases the risk for AD. Emerging evidence recommended that resistance in insulin production develops cognitive dysfunction, which generally leads to AD. Repurposing of antidiabetic drugs can be effective in preventing and treatment of the neurodegenerative disorder. Limitations of antidiabetic drugs restrict the repurposing of the drugs for other disorders. Therefore, nanotechnological intervention plays a significant role in the treatment of neurological disorders. In this review, we discuss the common cellular and molecular pathophysiologies between AD and type-II DM, the relevance of in vivo models of type II DM in the study of AD, and the repurposing of antidiabetic drugs and the nanodelivery systems of antidiabetic drugs against AD.

Advances in the Study of the Pathology and Treatment of Alzheimer's Disease and Its Association with Periodontitis

Alzheimer's disease (AD) has become one of the leading causes of health problems in the elderly, and studying its causes and treatments remains a serious challenge for researchers worldwide. The two main pathological features of Alzheimer's disease are the extracellular deposition of β-amyloid (Aβ) to form senile plaques and the intracellular aggregation of hyperphosphorylated Tau protein to form neurofibrillary tangles (NFTs). Researchers have proposed several hypotheses to elucidate the pathogenesis of AD, but due to the complexity of the pathophysiologic factors involved in the development of AD, no effective drugs have been found to stop the progression of the disease. Currently, the mainstay drugs used to treat AD can only alleviate the patient's symptoms and do not have a therapeutic effect. As researchers explore interactions among diseases, much evidence suggests that there is a close link between periodontitis and AD, and that periodontal pathogenic bacteria can exacerbate Aβ deposition and Tau protein hyperphosphorylation through neuroinflammatory mechanisms, thereby advancing the pathogenesis of AD. This article reviews recent advances in the pathogenesis of AD, available therapeutic agents, the relevance of periodontitis to AD, and mechanisms of action.

Multi-feature fusion learning for Alzheimer's disease prediction using EEG signals in resting state

Introduction

Diagnosing Alzheimer's disease (AD) lesions via visual examination of Electroencephalography (EEG) signals poses a considerable challenge. This has prompted the exploration of deep learning techniques, such as Convolutional Neural Networks (CNNs) and Visual Transformers (ViTs), for AD prediction. However, the classification performance of CNN-based methods has often been deemed inadequate. This is primarily attributed to CNNs struggling with extracting meaningful lesion signals from the complex and noisy EEG data.

Methods

In contrast, ViTs have demonstrated proficiency in capturing global signal patterns. In light of these observations, we propose a novel approach to enhance AD risk assessment. Our proposition involves a hybrid architecture, merging the strengths of CNNs and ViTs to compensate for their respective feature extraction limitations. Our proposed Dual-Branch Feature Fusion Network (DBN) leverages both CNN and ViT components to acquire texture features and global semantic information from EEG signals. These elements are pivotal in capturing dynamic electrical signal changes in the cerebral cortex. Additionally, we introduce Spatial Attention (SA) and Channel Attention (CA) blocks within the network architecture. These attention mechanisms bolster the model's capacity to discern abnormal EEG signal patterns from the amalgamated features. To make well-informed predictions, we employ a two-factor decision-making mechanism. Specifically, we conduct correlation analysis on predicted EEG signals from the same subject to establish consistency.

Results

This is then combined with results from the Clinical Neuropsychological Scale (MMSE) assessment to comprehensively evaluate the subject's susceptibility to AD. Our experimental validation on the publicly available OpenNeuro database underscores the efficacy of our approach. Notably, our proposed method attains an impressive 80.23% classification accuracy in distinguishing between AD, Frontotemporal dementia (FTD), and Normal Control (NC) subjects.

Discussion

This outcome outperforms prevailing state-of-the-art methodologies in EEG-based AD prediction. Furthermore, our methodology enables the visualization of salient regions within pathological images, providing invaluable insights for interpreting and analyzing AD predictions.

Elaeagnus umbellata: A miraculous shrub with potent health-promoting benefits from Northwest Himalaya

Medicinal plants encompassing a series of bioactive compounds have gained significant importance for use in the treatment of different diseases. Of them, Elaeagnus umbellata Thunb. (Deciduous shrub found in dappled shade, and sunny hedge) exhibits high medicinal value, with a widespread distribution across the Pir Panjal region of the Himalayas. Fruits serve as an excellent source of vitamins, minerals, and other essential compounds that exhibits hypolipidemic, hepatoprotective, and nephroprotective effects. The phytochemical fingerprint of berries revealed them to have a high content of polyphenols (with major proportion of anthocyanins), followed by monoterpenes and vitamin C. Extract of fruits help in regulating the digestion and absorption of glucose and reduces inflammation and oxidative stress. The phytosterols upholding anticoagulant activity serve the purpose of causing decrease in angina and the blood cholesterol levels. Phytochemicals such as eugenol, palmitic acid, and methyl palmitate exhibit potent antibacterial activity against broad range of disease-causing agents. Additionally, a high percentage of essential oils attribute it with the property of being effective against heart ailments. The present study highlights the importance of E. umbellata in traditional medicinal practices, and summarizes the knowledge of its bioactive constituents and a snapshot vision of remarkable biological activities like antimicrobial, antidiabetic, antioxidant, etc towards understanding its role in the development of efficient drug regimens for use in the treatment of different diseases. It also underlines the need to explore the plant on nutritional aspects to strengthen the existing knowledge pertaining to health promoting potential of E. umbellata.

Attenuation of Alzheimer's brain pathology in 5XFAD mice by PTH1-34, a peptide of parathyroid hormone

BACKGROUND

Alzheimer's disease (AD) and osteoporosis are two distinct diseases but often occur in the same patient. Their relationship remains poorly understood. Studies using Tg2576 AD animal model demonstrate bone deficits, which precede the brain phenotypes by several months, arguing for the independence of bone deficits on brain degeneration and raising a question if the bone deficits contribute to the AD development. To address this question, we investigated the effects of PTH_1-34, a peptide of parathyroid hormone analog and a well-recognized effective anabolic therapy drug for patients with osteoporosis, on 5XFAD animal model.

METHODS

5XFAD mice, an early onset β-amyloid (Aβ)-based AD mouse model, were treated with PTH_1-34 intermittently [once daily injection of hPTH_1-34 (50 μg/Kg), 5 days/week, starting at 2-month old (MO) for 2-3 month]. Wild type mice (C57BL/6) were used as control. The bone phenotypes were examined by microCT and evaluated by measuring serum bone formation and resorption markers. The AD relevant brain pathology (e.g., Aβ and glial activation) and behaviors were assessed by a combination of immunohistochemical staining analysis, western blots, and behavior tests. Additionally, systemic and brain inflammation were evaluated by serum cytokine array, real-time PCR (qPCR), and RNAscope.

RESULTS

A reduced trabecular, but not cortical, bone mass, accompanied with a decrease in bone formation and an increase in bone resorption, was detected in 5XFAD mice at age of 5/6-month old (MO). Upon PTH_1-34 treatments, not only these bone deficits but also Aβ-associated brain pathologies, including Aβ and Aβ deposition levels, dystrophic neurites, glial cell activation, and brain inflammatory cytokines, were all diminished; and the cognitive function was improved. Further studies suggest that PTH_1-34 acts on not only osteoblasts in the bone but also astrocytes in the brain, suppressing astrocyte senescence and expression of inflammatory cytokines in 5XFAD mice.

CONCLUSIONS

These results suggest that PTH_1-34 may act as a senolytic-like drug, reducing systemic and brain inflammation and improving cognitive function, and implicate PTH_1-34's therapeutic potential for patients with not only osteoporosis but also AD.

Cognitive- and memory-enhancing effects of Augmentin in Alzheimer’s rats through regulation of gene expression and neuronal cell apoptosis

Introduction: Alzheimer’s disease (AD) is the most common type of dementia among older persons. This study looked at how Augmentin affected behavior, gene expression, and apoptosis in rats in which AD had been induced by scopolamine.

Methods: The rats were divided into five groups: control, sham, memantine, Augmentin, and pre-Augmentin (the last group received Augmentin before scopolamine administration and was treated with memantine). A Morris water maze was utilized to measure spatial memory in the animals, and real-time quantitative reverse transcription PCR (qRT-PCR) and flow cytometry were employed to analyze gene expression and neuronal cell apoptosis, respectively.

Results: Memantine and Augmentin increased spatial memory in healthy rats. The use of scopolamine impaired spatial memory. Both Augmentin and memantine improved spatial memory in AD rats, particularly in the group that received memantine; however, the outcomes were more substantial when Augmentin was administered before scopolamine was given to induce AD. Furthermore, the expression of presenilin-2 (PSEN2) and inositol-trisphosphate 3-kinase B (ITPKB) increased, whereas the expression of DEAD-box helicase 5 (DDX5) fell in the AD-treated groups; however, the results were more substantial after combination therapy. According to flow cytometry studies, Augmentin pre-treatment reduced apoptosis in AD rats.

Discussion: The results showed that administering Augmentin to AD rats before memantine improved their spatial memory, reduced neuronal cell death, upregulated protective genes, and suppressed genes involved in AD pathogenesis.

Pathophysiology of Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease leading to dementia worldwide. While neuritic plaques consisting of aggregated amyloid-beta proteins and neurofibrillary tangles of accumulated tau proteins represent the pathophysiologic hallmarks of AD, numerous processes likely interact with risk and protective factors and one's culture to produce the cognitive loss, neuropsychiatric symptoms, and functional impairments that characterize AD dementia. Recent biomarker and neuroimaging research has revealed how the pathophysiology of AD may lead to symptoms, and as the pathophysiology of AD gains clarity, more potential treatments are emerging that aim to modify the disease and relieve its burden.

Branched-Chain Amino Acids Are Linked with Alzheimer's Disease-Related Pathology and Cognitive Deficits

Alzheimer's disease (AD) is an irreversible neurodegenerative disorder with a complex pathophysiology. Type 2 diabetes (T2D) is a strong risk factor for AD that shares similar abnormal features including metabolic dysregulation and brain pathology such as amyloid and/or Tau deposits. Emerging evidence suggests that circulating branched-chain amino acids (BCAAs) are associated with T2D. While excess BCAAs are shown to be harmful to neurons, its connection to AD is poorly understood. Here we show that individuals with AD have elevated circulating BCAAs and their metabolites compared to healthy individuals, and that a BCAA metabolite is correlated with the severity of dementia. APP_Swe mouse model of AD also displayed higher plasma BCAAs compared to controls. In pursuit of understanding a potential causality, BCAA supplementation to HT-22 neurons was found to reduce genes critical for neuronal health while increasing phosphorylated Tau. Moreover, restricting BCAAs from diet delayed cognitive decline and lowered AD-related pathology in the cortex and hippocampus in APP/PS1 mice. BCAA restriction for two months was sufficient to correct glycemic control and increased/restored dopamine that were severely reduced in APP/PS1 controls. Treating 5xFAD mice that show early brain pathology with a BCAA-lowering compound recapitulated the beneficial effects of BCAA restriction on brain pathology and neurotransmitters including norepinephrine and serotonin. Collectively, this study reveals a positive association between circulating BCAAs and AD. Our findings suggest that BCAAs impair neuronal functions whereas BCAA-lowering alleviates AD-related pathology and cognitive decline, thus establishing a potential causal link between BCAAs and AD progression.

Marine Sources of DHA-Rich Phospholipids with Anti-Alzheimer Effect

Alzheimer's disease (AD) is a complex and progressive disease, which affects millions of people around the world. Despite the many efforts over the years to find efficient therapeutics, there is no cure yet. Nonetheless, many compounds have been proven to decrease Alzheimer's symptoms. After a short overview of the hypotheses considered in AD drug development and the drugs approved for AD treatment, which lead to symptom release, we focus on the valorization of natural marine sources that decrease AD symptoms, particularly on docosahexaenoic acid (DHA), an important component in membrane phospholipids and the most abundant n-3 polyunsaturated fatty acids (PUFA) found in gray matter of the brain and in retina and on the DHA-containing phospholipids (DHA-PLs) present in marine sources, namely fish, krill, mollusks and in fisheries and aquaculture by-products. DHA-PLs' bioactivities are presented, namely their properties in anti-neurodegeneration, neuroinflammation, as anticancer agents, as well as their benefits to obesity and visual problems. Fisheries and aquaculture by-products are also highlighted as they have a high content of DHA and DHA-rich phospholipids, can be extracted by green methodologies and should be considered in a circular economy for a healthy sustainable future.

Discovery of novel α-carboline derivatives as glycogen synthase kinase-3β inhibitors for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disease, characterized by irreversible cognitive impairment, memory loss, and behavioral disturbances, ultimately resulting in death. The critical roles of glycogen synthase kinase-3β (GSK-3β) in tau pathology have also received considerable attention. Based on molecular docking studies, a series of novel α-carboline derivatives were designed, synthesized, and evaluated as GSK-3β inhibitors for their various biological activities. Among them, compound ZCH-9 showed the most potent inhibitory activity against GSK-3β, with an IC₅₀ value of 1.71 ± 0.09 µM. The cytotoxicity assay showed that ZCH-9 had low cytotoxicity toward the cell lines SH-SY5Y, HepG2, and HL-7702. Moreover, Western blot analysis indicated that ZCH-9 effectively inhibited hyperphosphorylation of the tau protein in okadaic acid-treated SH-SY5Y cells. The binding mode between ZCH-9 and GSK-3β was analyzed and further clarified throughout the molecular dynamics simulations. In general, these results suggested that the α-carboline-based small-molecule compounds could serve as potential candidates targeting GSK-3β for the treatment of AD.

Scan-Find-Scan-Model: Discrete Site-Targeted Suppressor Design Strategy for Amyloid-β

Alzheimer's disease is undoubtedly the most well-studied neurodegenerative disease. Consequently, the amyloid-β (Aβ) protein ranks at the top in terms of getting attention from the scientific community for structural property-based characterization. Even after decades of extensive research, there is existing volatility in terms of understanding and hence the effective tackling procedures against the disease that arises due to the lack of knowledge of both specific target- and site-specific drugs. Here, we develop a multidimensional approach based on the characterization of the common static-dynamic-thermodynamic trait of the monomeric protein, which efficiently identifies a small target sequence that contains an inherent tendency to misfold and consequently aggregate. The robustness of the identification of the target sequence comes with an abundance of a priori knowledge about the length and sequence of the target and hence guides toward effective designing of the target-specific drug with a very low probability of bottleneck and failure. Based on the target sequence information, we further identified a specific mutant that showed the maximum potential to act as a destabilizer of the monomeric protein as well as enormous success as an aggregation suppressor. We eventually tested the drug efficacy by estimating the extent of modulation of binding affinity existing within the fibrillar form of the Aβ protein due to a single-point mutation and hence provided a proof of concept of the entire protocol.

Recent progresses in exosome-based systems for targeted drug delivery to the brain

Despite the multiple ongoing and novel initiatives for developing brain-targeted drug delivery systems, insurmountable obstacles remain. A perfect drug delivery device that can bypass the brain-blood barrier and boost therapeutic efficacy is urgently needed for clinical applications. Exosomes hold unrivaled benefits as a drug delivery vehicle for treating brain diseases due to their endogenous and innate attributes. Unique properties, such as the ability to penetrate physical barriers, biocompatibility, innate targeting features, ability to leverage natural intracellular trafficking pathways, favored tumor homing, and stability, make exosomes suitable for brain-targeted drug delivery. Herein, we provide an overview of recent exosome-based drug delivery nanoplatforms and discuss how these inherent vesicles can be used to deliver therapeutic agents to the brain to cure neurodegenerative diseases, brain tumors, and other brain disorders. Moreover, we review the current roadblocks associated with exosomes and other brain-targeted drug delivery systems and discuss future directions for achieving successful therapy outcomes.

Melatonin Attenuates Methamphetamine-Induced Alteration of Amyloid β Precursor Protein Cleaving Enzyme Expressions via Melatonin Receptor in Human Neuroblastoma Cells

Alzheimer's disease (AD) is the most prominent neurodegenerative disease represented by the loss of memory and cognitive impairment symptoms and is one of the major health imperilments among the elderly. Amyloid (Aβ) deposit inside the neuron is one of the characteristic pathological hallmarks of this disease, leading to neuronal cell death. In the amyloidogenic processing, the amyloid precursor protein (APP) is cleaved by beta-secretase and γ-secretase to generate Aβ. Methamphetamine (METH) is a psychostimulant drug that causes neurodegeneration and detrimental cognitive deficits. The analogy between the neurotoxic and neurodegenerative profile of METH and AD pathology necessitates an exploration of the underlying molecular mechanisms. In the present study, we found that METH ineluctably affects APP processing, which might contribute to the marked production of Aβ in human neuroblastoma cells. Melatonin, an indolamine produced and released by the pineal gland as well as other extrapineal, has been protective against METH-induced neurodegenerative processes, thus rescuing neuronal cell death. However, the precise action of melatonin on METH has yet to be determined. We further propose to investigate the protective properties of melatonin on METH-induced APP-cleaving secretases. Pretreatment with melatonin significantly reversed METH-induced APP-cleaving secretases and Aβ production. In addition, pretreatment with luzindole, a melatonin receptor antagonist, significantly prevented the protective effect of melatonin, suggesting that the attenuation of the toxic effect on METH-induced APP processing by melatonin was mediated via melatonin receptor. The present results suggested that melatonin has a beneficial role in preventing Aβ generation in a cellular model of METH-induced AD.

Retracted systematic reviews were continued to be frequently cited: A Citation Analysis

OBJECTIVE

To survey the citations of retracted non-Cochrane systematic reviews (SRs) in scientific literature .

STUDY DESIGN AND SETTING

We searched the Web of Science and Google Scholar from their inception to 30 April 2020 to find the citations of 153 previously identified retracted non-Cochrane SRs. We calculated the numbers of citations before and after retraction separately. We also described how the citation addressed the retraction and how it was used in the article.

RESULTS

A We identified 954 citations of 128 retracted SRs. The number of retracted SRs and citations reached the peak in 2014 and 2016, respectively, and the majority of the citations (n=580, 60.8%) were in articles published after the SR was retracted. The mean number of citation per retracted SRs was 7.5. 2.6 before and 4.5 after the publication of the retraction notice. Twenty-nine (5.0%) citations indicated the retraction of the SRs in the reference section. Nine of these citations supported the retracted SR's results, and 15 disagreed with them.

CONCLUSION

Retracted SRs continue to be cited after the publication of the retraction notice. Standardized methods are needed to guide the management of retractions and avoid inappropriate citations of retracted articles.

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.

Contribution of Iranian researchers in Alzheimer's disease research: A 10 years scientometric analysis

Background

Alzheimer's disease is the most common form of dementia and is a rising issue for global health. Iran is struggling with a growing number of the elderly population and also a decrease in fertility rate. The goal of this study was to review and evaluate Alzheimer's disease publications by Iranian researchers.

Methods

We searched for Alzheimer and all its related keywords in the Web of Science to find related documents published by Iranian researchers from 2010 until 2019. Bibliometric parameters at the level of documents, authors, and organizations were assessed. The co-authorship matrix was computed using Bibexcel, and visualizations were performed by VOSviewer.

Results

Totally, 1042 documents from 4949 researchers (8.6 authors per document) were retrieved from Web of Science. Original articles (77.06%) and reviews (16.21%) were the most common document types for Iranian publications and also one article was retracted. As results, the average citation per document was 20.68. Iranian researchers mainly collaborated with researchers from the United States, Italy, Australia, and Canada, respectively. The co-occurrence networks for keywords represented five publication clusters in the collection. The largest cluster was related to studies on oxidative stress in Alzheimer's Disease, followed by in-vivo studies in the field of brain neurons destruction.

Conclusion

We found that Iranian researchers made significant impacts in the field of Alzheimer's disease and covered a wide range of related areas over the last 10 years.

Preserved Consciousness in Alzheimer's Disease and Other Dementias: Caregiver Awareness and Communication Strategies

Alzheimer's disease is an insidious onset neurodegenerative syndrome without effective treatment or cure. It is rapidly becoming a global health crisis that is overwhelming healthcare, society, and individuals. The clinical nature of neurocognitive decline creates significant challenges in bidirectional communication between caregivers and persons with Alzheimer's disease (AD) that can negatively impact quality-of-life. This paper sought to understand how and to what extent would awareness training about the levels of consciousness in AD influence the quality-of-life interactions in the caregiver-patient dyad. A literature review of multiple databases was conducted utilizing a transdisciplinary approach. The sum of findings indicates a positive relationship between enhanced caregiver awareness and training, positive interactions, and improved QOL measures among patients and caregivers. A multidirectional relationship was found among healthcare policies, training and education resources, caregivers, and persons with AD. Specifically, the current lack of policy and inadequate training and educational resources has various detrimental effects on patients and caregivers, while improvements in training and education of caregivers yields positive outcomes in communication and QOL. Furthermore, evidence of preserved consciousness in persons with AD was demonstrated from multiple disciplines, including neurobiological, psychological, and biopsychosocial models. The literature further revealed several methods to access the preserved consciousness in persons with AD and related dementias, including sensory, emotional, and cognitive stimulations. The evidence from the literature suggests a reframed approach to our understanding and treatment of persons with AD is not only warranted, but crucial to address the needs of those affected by AD.

All-d-Enantiomeric Peptide D3 Designed for Alzheimer's Disease Treatment Dynamically Interacts with Membrane-Bound Amyloid-β Precursors

Alzheimer's disease (AD) is a severe neurodegenerative pathology with no effective treatment known. Toxic amyloid-β peptide (Aβ) oligomers play a crucial role in AD pathogenesis. All-d-Enantiomeric peptide D3 and its derivatives were developed to disassemble and destroy cytotoxic Aβ aggregates. One of the D3-like compounds is approaching phase II clinical trials; however, high-resolution details of its disease-preventing or pharmacological actions are not completely clear. We demonstrate that peptide D3 stabilizing Aβ monomer dynamically interacts with the extracellular juxtamembrane region of a membrane-bound fragment of an amyloid precursor protein containing the Aβ sequence. MD simulations based on NMR measurement results suggest that D3 targets the amyloidogenic region, not compromising its α-helicity and preventing intermolecular hydrogen bonding, thus creating prerequisites for inhibition of early steps of Aβ conversion into β-conformation and its toxic oligomerization. An enhanced understanding of the D3 action molecular mechanism facilitates development of effective AD treatment and prevention strategies.

Systematic Search for a Predictor for the Clinical Observables of Alzheimer's Disease

One of the prevailing life-threatening incurable neurodegenerative diseases that are presently endangering human society as a whole, and hence, baffling the entire spectrum of the scientific and pharmaceutical world, is Alzheimer's disease (AD). AD is a manifestation of self-assembly of both wild-type (sporadic) and mutated (familial) forms of the amyloid-β peptide, a proteolytic product of the amyloid precursor protein, where the self-assembly results in the genesis of pathogenic fibrillar aggregates. Currently prevailing diagnostic and hence therapeutic challenges originate from the unavailability of a specific predictor for clinical observables. The continuous emergence of novel pathogenic mutants with unpredictable phenotypes adds immensely to the nonspecific nature of the problem. The current research reports a simple physical parameter, the binding affinity of a protofilament to its protofibril, which predicts the clinical observables of familial AD with astounding accuracy and more importantly, without any adjustable parameters.

Design, synthesis and biological evaluation of harmine derivatives as potent GSK-3β/DYRK1A dual inhibitors for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disease, characterized by irreversible cognitive impairment, memory loss and behavioral disturbances, ultimately leading to death. Glycogen synthase kinase 3β (GSK-3β) and dual-specificity tyrosine phosphorylation regulated kinase1A (DYRK1A) have gained a lot of attention for its role in tau pathology. To search for potential dual GSK-3β/DYRK1A inhibitors, we focused on harmine, a natural β-carboline alkaloid, which has been extensively studied for its various biological effects on the prevention of AD. In this study, a new series of harmine derivatives were designed, synthesized and evaluated as dual GSK-3β/DYRK1A inhibitors for their multiple biological activities. The in vitro results indicated that most of them displayed promising activity against GSK-3β and DYRK1A. Among them, compound ZDWX-25 showed potent inhibitory effects on GSK-3β and DYRK1A with IC50 values of 71 and 103 nM, respectively. Molecular modelling and kinetic studies verified that ZDWX-25 could interact with the ATP binding pocket of GSK-3β and DYRK1A. Western blot analysis revealed that ZDWX-25 inhibited hyperphosphorylation of tau protein in okadaic acid (OKA)-induced SH-SY5Y cells. In addition, ZDWX-25 showed good blood-brain barrier penetrability in vitro. More importantly, ZDWX-25 could ameliorate the impaired learning and memory in APP/PS1/Tau transgenic mice. These results indicated that the harmine-based compounds could be served as promising dual-targeted candidates for AD.

Sustained Hippocampal Neural Plasticity Questions the Reproducibility of an Amyloid-β-Induced Alzheimer's Disease Model

BACKGROUND

The use of Alzheimer's disease (AD) models obtained by intracerebral infusion of amyloid-β (Aβ) has been increasingly reported in recent years. Nonetheless, these models may present important challenges.

OBJECTIVE

We have focused on canonical mechanisms of hippocampal-related neural plasticity to characterize a rat model obtained by an intracerebroventricular (icv) injection of soluble amyloid-β42 (Aβ42).

METHODS

Animal behavior was evaluated in the elevated plus maze, Y-Maze spontaneous or forced alternation, Morris water maze, and open field, starting 2 weeks post-Aβ42 infusion. Hippocampal neurogenesis was assessed 3 weeks after Aβ42 injection. Aβ deposition, tropomyosin receptor kinase B levels, and neuroinflammation were appraised at 3 and 14 days post-Aβ42 administration.

RESULTS

We found that immature neuronal dendritic morphology was abnormally enhanced, but proliferation and neuronal differentiation in the dentate gyrus was conserved one month after Aβ42 injection. Surprisingly, animal behavior did not reveal changes in cognitive performance nor in locomotor and anxious-related activity. Brain-derived neurotrophic factor related-signaling was also unchanged at 3 and 14 days post-Aβ icv injection. Likewise, astrocytic and microglial markers of neuroinflammation in the hippocampus were unaltered in these time points.

CONCLUSION

Taken together, our data emphasize a high variability and lack of behavioral reproducibility associated with these Aβ injection-based models, as well as the need for its further optimization, aiming at addressing the gap between preclinical AD models and the human disorder.

Cerebrovascular phenotypes in mouse models of Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurological degenerative disorder and is the most common cause of dementia in the elderly. Clinically, AD manifests with memory and cognitive decline associated with deposition of hallmark amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs). Although the mechanisms underlying AD remains unclear, two hypotheses have been proposed. The established amyloid hypothesis states that Aβ accumulation is the basis of AD and leads to formation of NFTs. In contrast, the two-hit vascular hypothesis suggests that early vascular damage leads to increased accumulation of Aβ deposits in the brain. Multiple studies have reported significant morphological changes of the cerebrovasculature which can result in severe functional deficits. In this review, we delve into known structural and functional vascular alterations in various mouse models of AD and the cellular and molecular constituents that influence these changes to further disease progression. Many studies shed light on the direct impact of Aβ on the cerebrovasculature and how it is disrupted during the progression of AD. However, more research directed towards an improved understanding of how the cerebrovasculature is modified over the time course of AD is needed prior to developing future interventional strategies.

Relationship Between Amyloid-β Deposition and Blood-Brain Barrier Dysfunction in Alzheimer's Disease

Amyloid-β (Aβ) is the predominant pathologic protein in Alzheimer's disease (AD). The production and deposition of Aβ are important factors affecting AD progression and prognosis. The deposition of neurotoxic Aβ contributes to damage of the blood-brain barrier. However, the BBB is also crucial in maintaining the normal metabolism of Aβ, and dysfunction of the BBB aggravates Aβ deposition. This review characterizes Aβ deposition and BBB damage in AD, summarizes their interactions, and details their respective mechanisms.

Microwave-assisted rapid synthesis of spirooxindole-pyrrolizidine analogues and their activity as anti-amyloidogenic agents

A library of Sox-pyrrolizidines was rapidly prepared by microwave-assisted, one-pot, three-component, 1,3-dipolar cycloaddition of azomethine ylides from l-proline and isatin, with various β-nitrostyrenes. Nitro-Sox compounds, 4b, 4d and 4e inhibit HEWL amyloid fibril formation by ThT studies with percentages of fluorescence intensity of 55.4, 42.9 and 40.3%, respectively. Further studies with MTT assay, Raman spectroscopy, TEM and molecular docking supported these promising candidates for activity against amyloid misfolding, a phenomenon leading to Alzheimer's disease pathology.

Tuning the activity of iminosugars: novel N-alkylated deoxynojirimycin derivatives as strong BuChE inhibitors

We have designed unprecedented cholinesterase inhibitors based on 1-deoxynojirimycin as potential anti-Alzheimer’s agents. Compounds are comprised of three key structural motifs: the iminosugar, for interaction with cholinesterase catalytic anionic site (CAS); a hydrocarbon tether with variable lengths, and a fragment derived from 2-phenylethanol for promoting interactions with peripheral anionic site (PAS). Title compounds exhibited good selectivity towards BuChE, strongly depending on the substitution pattern and the length of the tether. The lead compounds were found to be strong mixed inhibitors of BuChE (IC₅₀ = 1.8 and 1.9 µM). The presumptive binding mode of the lead compound was analysed using molecular docking simulations, revealing H-bond interactions with the catalytic subsite (His438) and CAS (Trp82 and Glu197) and van der Waals interactions with PAS (Thr284, Pro285, Asn289). They also lacked significant antiproliferative activity against tumour and non-tumour cells at 100 µM, making them promising new agents for tackling Alzheimer’s disease through the cholinergic approach.

Homocysteine and Age-Related Central Nervous System Diseases: Role of Inflammation

Hyperhomocysteinemia (HHcy) is remarkably common among the aging population. The relation between HHcy and the development of neurodegenerative diseases, such as Alzheimer's disease (AD) and eye diseases, and age-related macular degeneration (AMD) and diabetic retinopathy (DR) in elderly people, has been established. Disruption of the blood barrier function of the brain and retina is one of the most important underlying mechanisms associated with HHcy-induced neurodegenerative and retinal disorders. Impairment of the barrier function triggers inflammatory events that worsen disease pathology. Studies have shown that AD patients also suffer from visual impairments. As an extension of the central nervous system, the retina has been suggested as a prominent site of AD pathology. This review highlights inflammation as a possible underlying mechanism of HHcy-induced barrier dysfunction and neurovascular injury in aging diseases accompanied by HHcy, focusing on AD.

Metabolic disorder in Alzheimer's disease

Alzheimer's disease (AD), a well known aging-induced neurodegenerative disease is related to amyloid proteinopathy. This proteinopathy occurs due to abnormalities in protein folding, structure and thereby its function in cells. The root cause of such kind of proteinopathy and its related neurodegeneration is a disorder in metabolism, rather metabolomics of the major as well as minor nutrients. Metabolomics is the most relevant "omics" platform that offers a great potential for the diagnosis and prognosis of neurodegenerative diseases as an individual's metabolome. In recent years, the research on such kinds of neurodegenerative diseases, especially aging-related disorders is broadened its scope towards metabolic function. Different neurotransmitter metabolisms are also involved with AD and its associated neurodegeneration. The genetic and epigenetic backgrounds are also noteworthy. In this review, the physiological changes of AD in relation to its corresponding biochemical, genetic and epigenetic involvements including its (AD) therapeutic aspects are discussed.

In Vitro Propagation, Huperzine A Content and Antioxidant Activity of Three Genotypic Huperzia serrata

Huperzia serrata is a traditional herb and endangered Chinese medicinal material, which has attracted much attention due to its production of Huperzine A (HupA). In vitro propagation of H. serrata is considered a new way to relieve the resource pressure of H. serrata. In this study, three different genotypic wild H. serrata were used for in vitro propagation. Then, the antioxidant activity and the content of HupA in the regenerated H. serrata were investigated. The results showed the survival rate of the explant was increased to 25.37% when using multiple sterilization processes. The best induction medium for H. serrata was the Schenk and Hildebrandt (SH) medium supplemented with 0.5 mg·L^-1 Naphthalene acetic acid (NAA) and 0.1 mg·L^-1 2,4-Dichlorophenoxyacetic acid (2,4-D), where the regeneration rate of the explant was to 57.04%. The best proliferation medium was the SH medium with NAA (1.0 mg·L^-1), as the biomass of in vitro tissue increased 164.17 ± 0.41 times. High-performance liquid chromatography analysis showed that the in vitro culture of three genotypes could produce HupA and the content of HupA was 53.90-87.17 µg·g^-1. The antioxidant experiment showed that the methanol extract of in vitro H. serrata had higher antioxidant activity than that of wild H. serrata. This study provides a reliable in vitro H. serrata culture protocol and laid an important foundation for the antioxidant capacity of the thallus and the content of HupA.

Poria cocos could ameliorate cognitive dysfunction in APP/PS1 mice by restoring imbalance of Aβ production and clearance and gut microbiota dysbiosis

Alzheimer's disease (AD) is the most common neurodegenerative disorder. Amyloid beta-protein (Aβ) plaques, which are the hallmark of AD, are formed from the imbalance of Aβ production and clearance accompanied by neuroinflammation, gut dysbiosis, and metabolite dysfunction. All of these processes give rise to neurochemical deficiencies and synaptic dysfunction, which ultimately contribute to recognition dysfunction. Poria cocos (PC), which contains multiple active ingredients, plays a significant role in the treatment of multiple-pathogenesis senile diseases such as AD. Nevertheless, there are only very few investigations on the intricate action mechanism of PC for the treatment of AD. In this study, we evaluate the multi-target cure effect of PC on APP/PS1 mice by behavioral, immunohistochemical (IHC), targeted metabolomics, and 16S rRNA sequencing experiments. Mice treated with PC showed significant improvements in cognitive function as evaluated by the behavioral experiment. IHC revealed that PC treatment relieved Aβ deposition by reducing the formation of Aβ and increasing its clearance. Moreover, PC treatment improved gut dysbiosis, which reversed the metabolite dysfunction of bile acid. These findings reveal that PC is a promising therapeutic agent, which might ameliorate the cognitive function of AD by restoring the imbalance of Aβ production and clearance and gut microbiota dysbiosis.

Alzheimer's Disease: Related Targets, Synthesis of Available Drugs, Bioactive Compounds Under Development and Promising Results Obtained from Multi-target Approaches

We describe herein the therapeutic targets involved in Alzheimer's disease as well as the available drugs and their synthetic routes. Bioactive compounds under development are also exploited to illustrate some recent research advances on the medicinal chemistry of Alzheimer's disease, including structure-activity relationships for some targets. The importance of multi-target approaches, including some examples from our research projects, guides new perspectives in search of more effective drug candidates. This review comprises the period between 2001 and early 2020.

Profiling the Tox21 Chemical Collection for Acetylcholinesterase Inhibition

BACKGROUND

Inhibition of acetylcholinesterase (AChE), a biomarker of organophosphorous and carbamate exposure in environmental and occupational human health, has been commonly used to identify potential safety liabilities. So far, many environmental chemicals, including drug candidates, food additives, and industrial chemicals, have not been thoroughly evaluated for their inhibitory effects on AChE activity. AChE inhibitors can have therapeutic applications (e.g., tacrine and donepezil) or neurotoxic consequences (e.g., insecticides and nerve agents).

OBJECTIVES

The objective of the current study was to identify environmental chemicals that inhibit AChE activity using in vitro and in silico models.

METHODS

To identify AChE inhibitors rapidly and efficiently, we have screened the Toxicology in the 21st Century (Tox21) 10K compound library in a quantitative high-throughput screening (qHTS) platform by using the homogenous cell-based AChE inhibition assay and enzyme-based AChE inhibition assays (with or without microsomes). AChE inhibitors identified from the primary screening were further tested in monolayer or spheroid formed by SH-SY5Y and neural stem cell models. The inhibition and binding modes of these identified compounds were studied with time-dependent enzyme-based AChE inhibition assay and molecular docking, respectively.

RESULTS

A group of known AChE inhibitors, such as donepezil, ambenonium dichloride, and tacrine hydrochloride, as well as many previously unreported AChE inhibitors, such as chelerythrine chloride and cilostazol, were identified in this study. Many of these compounds, such as pyrazophos, phosalone, and triazophos, needed metabolic activation. This study identified both reversible (e.g., donepezil and tacrine) and irreversible inhibitors (e.g., chlorpyrifos and bromophos-ethyl). Molecular docking analyses were performed to explain the relative inhibitory potency of selected compounds.

CONCLUSIONS

Our tiered qHTS approach allowed us to generate a robust and reliable data set to evaluate large sets of environmental compounds for their AChE inhibitory activity. https://doi.org/10.1289/EHP6993.

Navigating Alzheimer's Disease via Chronic Stress: The Role of Glucocorticoids

Alzheimer's disease (AD) is a chronic intensifying incurable progressive disease leading to neurological deterioration manifested as impairment of memory and executive brain functioning affecting the physical ability like intellectual brilliance, common sense in patients. The recent therapeutic approach in Alzheimer's disease is only the symptomatic relief further emerging the need for therapeutic strategies to be targeted in managing the underlying silent killing progression of dreaded pathology. Therefore, the current research direction is focused on identifying the molecular mechanisms leading to the evolution of the understanding of the neuropathology of Alzheimer's disease. The resultant saturation in the area of current targets (amyloid β, τ Protein, oxidative stress etc.) has led the scientific community to rethink of the mechanistic neurodegenerative pathways and reprogram the current research directions. Although, the role of stress has been recognized for many years and contributing to the development of cognitive impairment, the area of stress has got the much-needed impetus recently and is being recognized as a modifiable menace for AD. Stress is an unavoidable human experience that can be resolved and normalized but chronic activation of stress pathways unsettle the physiological status. Chronic stress mediated activation of neuroendocrine stimulation is generally linked to a high risk of developing AD. Chronic stress-driven physiological dysregulation and hypercortisolemia intermingle at the neuronal level and leads to functional (hypometabolism, excitotoxicity, inflammation) and anatomical remodeling of the brain architecture (senile plaques, τ tangles, hippocampal atrophy, retraction of spines) ending with severe cognitive deterioration. The present review is an effort to collect the most pertinent evidence that support chronic stress as a realistic and modifiable therapeutic earmark for AD and to advocate glucocorticoid receptors as therapeutic interventions.

The Neuroprotective Properties, Functions, and Roles of Cannabis sativa in Selected Diseases Related to the Nervous System

BACKGROUND

Cannabis and its extracts are now being explored due to their huge health benefits. Although, the effect they elicit, whether on humans or rodents, may vary based on the age of the animal/subject and or the time in which the extract is administered. However, several debates exist concerning the various medical applications of these compounds. Nonetheless, their applicability as therapeutics should not be clouded based on their perceived negative biological actions.

METHODS

Articles from reliable databases such as Science Direct, PubMed, Google Scholar, Scopus, and Ovid were searched. Specific search methods were employed using multiple keywords: ''Medicinal Cannabis; endocannabinoid system; cannabinoids receptors; cannabinoids and cognition; brain disorders; neurodegenerative diseases''. For the inclusion/exclusion criteria, only relevant articles related to medicinal Cannabis and its various compounds were considered.

RESULTS

The current review highlights the role, effects, and involvement of Cannabis, cannabinoids, and endocannabinoids in preventing selected neurodegenerative diseases and possible amelioration of cognitive impairments. Furthermore, it also focuses on Cannabis utilization in many disease conditions such as Alzheimer's and Parkinson's disease among others.

CONCLUSION

In conclusion, the usage of Cannabis should be further explored as accumulating evidence suggests that it could be effective and somewhat safe, especially when adhered to the recommended dosage. Furthermore, in-depth studies should be conducted in order to unravel the specific mechanism underpinning the involvement of cannabinoids at the cellular level and their therapeutic applications.

Effects of Spices (Saffron, Rosemary, Cinnamon, Turmeric and Ginger) in Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent dementia in the elderly, causing disability, physical, psychological, social, and economic damage to the individual, their families, and caregivers. Studies have shown some spices, such as saffron, rosemary, cinnamon, turmeric, and ginger, have antioxidant and anti-inflammatory properties that act in inhibiting the aggregation of acetylcholinesterase and amyloid in AD. For this reason, spices have been studied as beneficial sources against neurodegenerative diseases, including AD. In this sense, this study aims to present a review of some spices (Saffron, Rosemary, Cinnamon, Turmeric and Ginger) and their bioactive compounds, most consumed and investigated in the world regarding AD. In this article, scientific evidence is compiled in clinical trials in adults, the elderly, animals, and in vitro, on properties considered neuroprotective, having no or negative effects on neuroprotection of these spices and their bioactive compounds. The importance of this issue is based on the pharmacological treatment for AD that is still not very effective. In addition, the recommendations and prescriptions of these spices are still permeated by questioning and lack of robust evidence of their effects on neurodegeneration. The literature search suggests all spices included in this article have bioactive compounds with anti-inflammatory and antioxidant actions associated with neuroprotection. To date, the amounts of spice ingestion in humans are not uniform, and there is no consensus on its indication and chronic consumption guarantees safety and efficacy in neuroprotection. Therefore, clinical evidence on this topic is necessary to become a formal adjuvant treatment for AD.

Hybrid diffusion tensor imaging feature-based AD classification

BACKGROUND

Effective detection of Alzheimer's disease (AD) is still difficult in clinical practice. Therefore, establishment of AD detection model by means of machine learning is of great significance to assist AD diagnosis.

OBJECTIVE

To investigate and test a new detection model aiming to help doctors diagnose AD more accurately.

METHODS

Diffusion tensor images and the corresponding T1w images acquired from subjects (AD = 98, normal control (NC) = 100) are used to construct brain networks. Then, 9 types features (198×90×9 in total) are extracted from the 3D brain networks by a graph theory method. Features with low correction in both groups are selected through the Pearson correlation analysis. Finally, the selected features (198×33, 198×26, 198×30, 198×42, 198×36, 198×23, 198×29, 198×14, 198×25) are separately used into train 3 machine learning classifier based detection models in which 60% of study subjects are used for training, 20% for validation and 20% for testing.

RESULTS

The best detection accuracy levels of 3 models are 90%, 98% and 90% with the corresponding sensitivity of 92%, 96%, and 72% and specificity of 88%, 100% and 94% when using a random forest classifier trained with the Shortest Path Length (SPL) features (198×14), a support vector machine trained with the Degree Centrality features (198×33), and a convolution neural network trained with SPL features, respectively.

CONCLUSIONS

This study demonstrates that the new method and models not only improve the accuracy of detecting AD, but also avoid bias caused by the method of direct dimensionality reduction from high dimensional data.

Liposomes Decorated with 2-(4'-Aminophenyl)benzothiazole Effectively Inhibit Aβ1-42 Fibril Formation and Exhibit in Vitro Brain-Targeting Potential

The potential of 2-benzothiazolyl-decorated liposomes as theragnostic systems for Alzheimer's disease was evaluated in vitro, using PEGylated liposomes that were decorated with two types of 2-benzothiazoles: (i) the unsubstituted 2-benzothiazole (BTH) and (ii) the 2-(4-aminophenyl)benzothiazole (AP-BTH). The lipid derivatives of both BTH-lipid and AP-BTH-lipid were synthesized, for insertion in liposome membranes. Liposomes (LIP) containing three different concentrations of benzothiazoles (5, 10, and 20%) were formulated, and their stability, integrity in the presence of serum proteins, and their ability to inhibit β-amyloid (1-42) (Αβ42) peptide aggregation (by circular dichroism (CD) and thioflavin T (ThT) assay), were evaluated. Additionally, the interaction of some LIP with an in vitro model of the blood-brain barrier (BBB) was studied. All liposome types ranged between 92 and 105 nm, with the exception of the 20% AP-BTH-LIP that were larger (180 nm). The 5 and 10% AP-BTH-LIP were stable when stored at 4 °C for 40 days and demonstrated high integrity in the presence of serum proteins for 7 days at 37 °C. Interestingly, CD experiments revealed that the AP-BTH-LIP substantially interacted with Αβ42 peptides and inhibited fibril formation, as verified by ThT assay, in contrast with the BTH-LIP, which had no effect. The 5 and 10% AP-BTH-LIP were the most effective in inhibiting Αβ42 fibril formation. Surprisingly, the AP-BTH-LIP, especially the 5% ones, demonstrated high interaction with brain endothelial cells and high capability to be transported across the BBB model. Taken together, the current results reveal that the 5% AP-BTH-LIP are of high interest as novel targeted theragnostic systems against AD, justifying further in vitro and in vivo exploitation.

Forsythoside B attenuates memory impairment and neuroinflammation via inhibition on NF-κB signaling in Alzheimer's disease

Background

Neuroinflammation is a principal element in Alzheimer’s disease (AD) pathogenesis, so anti-inflammation may be a promising therapeutic strategy. Forsythoside B (FTS•B), a phenylethanoid glycoside isolated from Forsythiae fructus, has been reported to exert anti-inflammatory effects. However, no studies have reported whether the anti-inflammatory properties of FTS•B have a neuroprotective effect in AD. In the present study, these effects of FTS•B were investigated using amyloid precursor protein/presenilin 1 (APP/PS1) mice, BV-2 cells, and HT22 cells.

Methods

APP/PS1 mice were administered FTS•B intragastrically for 36 days. Behavioral tests were then carried out to examine cognitive functions, including the Morris water maze, Y maze, and open field experiment. Immunohistochemistry was used to analyze the deposition of amyloid-beta (Aβ), the phosphorylation of tau protein, and the levels of 4-hydroxynonenal, glial fibrillary acidic protein, and ionized calcium-binding adapter molecule 1 in the hippocampus. Proteins that showed marked changes in levels related to neuroinflammation were identified using proteomics and verified using enzyme-linked immunosorbent assay and western blot. BV-2 and HT22 cells were also used to confirm the anti-neuroinflammatory effects of FTS•B.

Results

In APP/PS1 mice, FTS•B counteracted cognitive decline, ameliorated the deposition of Aβ and the phosphorylation of tau protein, and attenuated the activation of microglia and astrocytes in the cortex and hippocampus. FTS•B affected vital signaling, particularly by decreasing the activation of JNK-interacting protein 3/C-Jun NH2-terminal kinase and suppressing WD-repeat and FYVE-domain-containing protein 1/toll-like receptor 3 (WDFY1/TLR3), further suppressing the activation of nuclear factor-κB (NF-κB) signaling. In BV-2 and HT22 cells, FTS•B prevented lipopolysaccharide-induced neuroinflammation and reduced the microglia-mediated neurotoxicity.

Conclusions

FTS•B effectively counteracted cognitive decline by regulating neuroinflammation via NF-κB signaling in APP/PS1 mice, providing preliminary experimental evidence that FTS•B is a promising therapeutic agent in AD treatment.