Molecular mechanisms in Alzheimer's disease and related potential treatments such as structural target convergence of antibodies and simple organic molecules

Gamma oscillation modulation for cognitive impairment: A systematic review

BackgroundGamma oscillation modulation has emerged as a potential non-invasive treatment to counteract cognitive impairment in Alzheimer's disease (AD) and mild cognitive impairment (MCI). Non-invasive brain stimulation techniques like transcranial alternating current stimulation (tACS), gamma sensory stimulation (GSS), and transcranial magnetic stimulation (TMS) show promise in supporting specific cognitive functions.ObjectiveTo review and evaluate the efficacy of gamma oscillation modulation techniques in benefiting cognitive functions among individuals with AD and MCI.MethodsA systematic review was conducted, analyzing studies from 2015 to 2023 across databases such as PubMed, Web of Science, and Scopus. Inclusion criteria focused on studies involving tACS, GSS, or TMS applied to older adults with MCI or AD. A total of 438 articles were screened, of which 10 met the eligibility criteria.ResultsFindings suggest that gamma tACS, especially targeting the precuneus and dorsolateral prefrontal cortex, benefits episodic memory and cognitive performance. GSS also showed potential in supporting memory and attention, while TMS exhibited inconsistent but promising results when applied to the angular gyrus. However, heterogeneity in study designs and small sample sizes limit the generalizability of these outcomes.ConclusionsGamma oscillation modulation offers potential cognitive benefits for patients with AD and MCI, particularly in memory support. Further studies with larger samples and well-designed protocols are needed to confirm its therapeutic efficacy and optimize intervention parameters.

Structure-Activity Relationship of Fluorinated Benzenesulfonamides as Inhibitors of Amyloid-β Aggregation

Amyloid-beta aggregation is considered one of the factors influencing the onset of the Alzheimer's disease. Early prevention of such aggregation should alleviate disease condition by applying small molecule compounds that shift the aggregation equilibrium toward the soluble form of the peptide or slow down the process. We have discovered that fluorinated benzenesulfonamides of particular structure slowed the amyloid-beta peptide aggregation process by more than three-fold. We synthesized a series of ortho-para and meta-para double-substituted fluorinated benzenesulfonamides that inhibited the aggregation process to a variable extent yielding a detailed picture of the structure-activity relationship. Analysis of compound chemical structure effect on aggregation in artificial cerebrospinal fluid showed the necessity to arrange the benzenesulfonamide, hydrophobic substituent, and benzoic acid in a particular way. The amyloid beta peptide aggregate fibril structures varied in cross-sectional height depending on the applied inhibitor indicating the formation of a complex with the compound. Application of selected inhibitors increased the survivability of cells affected by the amyloid beta peptide. Such compounds may be developed as drugs against Alzheimer's disease.

Lead optimization based design, synthesis, and pharmacological evaluation of quinazoline derivatives as multi-targeting agents for Alzheimer's disease treatment

The complexity and multifaceted nature of Alzheimer's disease (AD) have driven us to further explore quinazoline scaffolds as multi-targeting agents for AD treatment. The lead optimization strategy was utilized in designing of new series of derivatives (AK-1 to AK-14) followed by synthesis, characterization, and pharmacological evaluation against human cholinesterase's (hChE) and β-secretase (hBACE-1) enzymes. Amongst them, compounds AK-1, AK-2, and AK-3 showed good and significant inhibitory activity against both hAChE and hBACE-1 enzymes with favorable permeation across the blood-brain barrier. The most active compound AK-2 revealed significant propidium iodide (PI) displacement from the AChE-PAS region and was non-neurotoxic against SH-SY5Y cell lines. The lead molecule (AK-2) also showed Aβ aggregation inhibition in a self- and AChE-induced Aβ aggregation, Thioflavin-T assay. Further, compound AK-2 significantly ameliorated Aβ-induced cognitive deficits in the Aβ-induced Morris water maze rat model and demonstrated a significant rescue in eye phenotype in the Aꞵ-phenotypic drosophila model of AD. Ex-vivo immunohistochemistry (IHC) analysis on hippocampal rat brains showed reduced Aβ and BACE-1 protein levels. Compound AK-2 suggested good oral absorption via pharmacokinetic studies and displayed a good and stable ligand-protein interaction in in-silico molecular modeling analysis. Thus, the compound AK-2 can be regarded as a lead molecule and should be investigated further for the treatment of AD.

Could protein phosphatase 2A and glycogen synthase kinase-3 beta be targeted by natural compounds to ameliorate Alzheimer's pathologies?

Alzheimer's disease (AD) is a progressive neurological disorder that impairs memory and cognitive abilities, primarily in the elderly. The burden of AD extends beyond patients, impacting families and caregivers due to the patients' reliance on assistance for daily tasks. The main features of the pathogenesis of AD are beta-amyloid plaques and neurofibrillary tangles (NFTs), that strongly correlate with oxidative stress and inflammation. NFTs result from misfolded and hyperphosphorylated tau proteins. Various studies have focused on tau phosphorylation, indicating protein phosphatase 2A (PP2A) as the primary tau phosphatase and glycogen synthase kinase-3 beta (GSK-3β) as the leading tau kinase. Experimental evidence suggests that inhibition of PP2A and increased GSK-3β activity contribute to neuroinflammation, oxidative stress, and cognitive impairment. Hence, targeting PP2A and GSK-3β with pharmacological approaches shows promise in treating AD. The use of natural compounds in the drug development for AD have been extensively studied for their antioxidant, anti-inflammatory, anti-cholinesterase, and neuroprotective properties, demonstrating therapeutic advantages in neurological diseases. Alongside the development of PP2A activator and GSK-3β inhibitor drugs, natural compounds are likely to have neuroprotective effects by increasing PP2A activity and decreasing GSK-3β levels. Therefore, based on the preclinical and clinical studies, the potential of PP2A and GSK-3β as therapeutic targets of natural compounds are highlighted in this review.

Neuroprotective effects of dipeptidyl peptidase 4 inhibitor on Alzheimer's disease: a narrative review

Insulin resistance in brain and amyloidogenesis are principal pathological features of diabetes-related cognitive decline and development of Alzheimer's disease (AD). A growing body of evidence suggests that maintaining glucose under control in diabetic patients is beneficial for preventing AD development. Dipeptidyl peptidase 4 inhibitors (DDP4is) are a class of novel glucose-lowering medications through increasing insulin excretion and decreasing glucagon levels that have shown neuroprotective potential in recent studies. This review consolidates extant evidence from earlier and new studies investigating the association between DPP4i use, AD, and other cognitive outcomes. Beyond DPP4i's benefits in alleviating insulin resistance and glucose-lowering, underlying mechanisms for the potential neuroprotection with DPP4i medications were categorized into the following sections: (Ferrari et al., Physiol Rev, 2021, 101, 1,047-1,081): the benefits of DPP4is on directly ameliorating the burden of β-amyloid plaques and reducing the formation of neurofibrillary tangles; DPP4i increasing the bioactivity of neuroprotective DPP4 substrates including glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and stromal-derived factor-1α (SDF-1α) etc.; pleiotropic effects of DPP4is on neuronal cells and intracerebral structure including anti-inflammation, anti-oxidation, and anti-apoptosis. We further revisited recently published epidemiological studies that provided supportive data to compliment preclinical evidence. Given that there remains a lack of completed randomized trials that aim at assessing the effect of DPP4is in preventing AD development and progression, this review is expected to provide a useful insight into DPP4 inhibition as a potential therapeutic target for AD prevention and treatment. The evidence is helpful for informing the rationales of future clinical research and guiding evidence-based clinical practice.

Recent Molecular Targets and their Ligands for the Treatment of Alzheimer Disease

Alzheimer's disease is a multifaceted neurodegenerative disease. Cholinergic dysfunction, amyloid β toxicity, tauopathies, oxidative stress, neuroinflammation are among the main pathologies of the disease. Ligands targeting more than one pathology, multi-target directed ligands, attract attention in the recent years to tackle Alzheimer's disease. In this review, we aimed to cover different biochemical pathways, that are revealed in recent years for the pathology of the disease, as druggable targets such as cannabinoid receptors, matrix metalloproteinases, histone deacetylase and various kinases including, glycogen synthase kinase-3, mitogen-activated protein kinase and c-Jun N-terminal kinase, and their ligands for the treatment of Alzheimer's disease in the hope of providing more realistic insights into the field.

Multifunctional nanoparticle-mediated combining therapy for human diseases

Combining existing drug therapy is essential in developing new therapeutic agents in disease prevention and treatment. In preclinical investigations, combined effect of certain known drugs has been well established in treating extensive human diseases. Attributed to synergistic effects by targeting various disease pathways and advantages, such as reduced administration dose, decreased toxicity, and alleviated drug resistance, combinatorial treatment is now being pursued by delivering therapeutic agents to combat major clinical illnesses, such as cancer, atherosclerosis, pulmonary hypertension, myocarditis, rheumatoid arthritis, inflammatory bowel disease, metabolic disorders and neurodegenerative diseases. Combinatorial therapy involves combining or co-delivering two or more drugs for treating a specific disease. Nanoparticle (NP)-mediated drug delivery systems, i.e., liposomal NPs, polymeric NPs and nanocrystals, are of great interest in combinatorial therapy for a wide range of disorders due to targeted drug delivery, extended drug release, and higher drug stability to avoid rapid clearance at infected areas. This review summarizes various targets of diseases, preclinical or clinically approved drug combinations and the development of multifunctional NPs for combining therapy and emphasizes combinatorial therapeutic strategies based on drug delivery for treating severe clinical diseases. Ultimately, we discuss the challenging of developing NP-codelivery and translation and provide potential approaches to address the limitations. This review offers a comprehensive overview for recent cutting-edge and challenging in developing NP-mediated combination therapy for human diseases.

Carbamate as a potential anti-Alzheimer's pharmacophore: A review

Alzheimer's disease (AD) is a progressive age-related neurodegenerative brain disorder, which leads to loss of memory and other cognitive dysfunction. The underlying mechanisms of AD pathogenesis are very complex and still not fully explored. Cholinergic neuronal loss, accumulation of amyloid plaque, metal ions dyshomeostasis, tau hyperphosphorylation, oxidative stress, neuroinflammation, and mitochondrial dysfunction are major hallmarks of AD. The current treatment options for AD are acetylcholinesterase inhibitors (donepezil, rivastigmine, and galantamine) and NMDA receptor antagonists (memantine). These FDA-approved drugs mainly provide symptomatic relief without addressing the pathological aspects of disease progression. So, there is an urgent need for novel drug development that not only addresses the basic mechanisms of the disease but also shows the neuroprotective property. Various research groups across the globe are working on the development of multifunctional agents for AD amelioration using different core scaffolds for their design, and carbamate is among them. Rivastigmine was the first carbamate drug investigated for AD management. The carbamate fragment, a core scaffold of rivastigmine, act as a potential inhibitor of acetylcholinesterase. In this review, we summarize the last 10 years of research conducted on the modification of carbamate with different substituents which primarily target ChE inhibition, reduce oxidative stress, and modulate Aβ aggregation.

Berberine derivatives as inhibitors of acetylcholinesterase: A systematic review

Alzheimer's disease (AD) is a chronic age-related neurodegenerative brain disorder characterized by the impairment of memory accompanied by worsening of thinking ability of an individual. The exact pathophysiology of AD is not fully understood. However low level of the neurotransmitter named acetylcholine (ACh), aggregation of Aβ peptide into toxic Aβ plaque, hyperphosphorylation of tau, bio-metal imbalance, and oxidative stress are the main hallmarks of this disease. Due to the complex pathophysiology of AD, no specific treatment is available in the market, and treatment is only limited to the symptomatic relief. So, there is an urgent need for the development of new drug candidate, which can have disease-modifying effect and improve learning and memory in AD patient. Therefore, berberine-based multifunction compounds with potential cholinesterase inhibitory properties were reviewed in this article. Structure-activity relationship (SAR) and biological activity provide highlights on the new derivatives used for the management of AD.

Tryptamine: A privileged scaffold for the management of Alzheimer's disease

Alzheimer's disease (AD) is a chronic and irreversible neurodegenerative disease associated with aging. It is characterized by the progressive loss of memory and other cognitive functions. Although the exact etiology of AD is not well explored, several factors, such as the deposition of amyloid-β (Aβ) plaques, hyperphosphorylation of tau protein, presence of low levels of acetylcholine, and generation of oxidative stress, are key mediators in the progression of AD. Currently, the clinical treatment options for AD are limited and are based on cholinesterase (ChE) inhibitors (e.g., donepezil, rivastigmine, and galantamine), N-methyl- d-aspartic acid receptor antagonists (e.g., memantine), and the recently approved Aβ modulator (e.g., aducanumab). Tryptamine (2-(1H-indol-3-yl)ethan-1-amine) is a small molecule that contains an indole nucleus and an ethylamine side chain. It is also the active metabolite of tryptophan. It possesses a wide range of biological activities related to neurodegenerative disorders, such as ChE inhibition, Aβ aggregation inhibition, antioxidant effects, monoamine-oxidase inhibition, and neuroprotection. Several tryptamine-based hybrid analogs are currently being investigated as multifunctional agents for the development of novel hybrids for AD treatment. Thus, this review article aims to provide in-depth insights into the research progress and strategies for designing multifunctional agents used in Alzheimer's therapy.

Update on new trends and progress of natural active ingredients in the intervention of Alzheimer's disease, based on understanding of traditional Chinese and Western relevant theories: A review

Alzheimer's disease (AD) is one of the major neurological disorders causing death in the elderly worldwide. As a neurodegenerative disease that is difficult to prevent and cure, the pathogenesis of AD is complex and there is no effective cure. A variety of natural products derived from plants have been reported to have promising anti-AD activities, including flavonoids, terpenes, phenolic acids and alkaloids, which can effectively relieve the symptoms of AD in a variety of ways. This paper mainly reviews the pharmacological activity and mechanisms of natural products against AD. Although the clinical efficacy of these plants still needs to be determined by further high-quality studies, it may also provide a basis for future researchers to study anti-AD in depth.

Getting ahead of Alzheimer's disease: early intervention with focused ultrasound

The amyloid-β (Aβ) hypothesis implicates Aβ protein accumulation in Alzheimer's disease (AD) onset and progression. However, therapies targeting Aβ have proven insufficient in achieving disease reversal, prompting a shift to focus on early intervention and alternative therapeutic targets. Focused ultrasound (FUS) paired with systemically-introduced microbubbles (μB) is a non-invasive technique for targeted and transient blood-brain barrier opening (BBBO), which has demonstrated Aβ and tau reduction, as well as memory improvement in models of late-stage AD. However, similar to drug treatments for AD, this approach is not sufficient for complete reversal of advanced, symptomatic AD. Here we aim to determine whether early intervention with FUS-BBBO in asymptomatic AD could delay disease onset. Thus, the objective of this study is to measure the protective effects of FUS-BBBO on anxiety, memory and AD-associated protein levels in female and male triple transgenic (3xTg) AD mice treated at an early age and disease state. Here we show that early, repeated intervention with FUS-BBBO decreased anxiety-associated behaviors in the open field test by 463.02 and 37.42% in male and female cohorts, respectively. FUS-BBBO preserved female aptitude for learning in the active place avoidance paradigm, reducing the shock quadrant time by 30.03 and 31.01% in the final long-term and reversal learning trials, respectively. Finally, FUS-BBBO reduced hippocampal accumulation of Aβ40, Aβ42, and total tau in females by 12.54, 13.05, and 3.57%, respectively, and reduced total tau in males by 18.98%. This demonstration of both cognitive and pathological protection could offer a solution for carriers of AD-associated mutations as a safe, non-invasive technique to delay the onset of the cognitive and pathological effects of AD.

In-depth investigation of the mechanisms of Schisandra chinensis polysaccharide mitigating Alzheimer's disease rat via gut microbiota and feces metabolomics

Schisandra chinensis (S. chinensis) is an herbal medicine used for the treatment of Alzheimer's disease (AD). The purified polysaccharide fraction, namely SCP2, was previously isolated from S. chinensis crude polysaccharide (SCP) and its structure and in vitro activity were investigated. However, the in vivo activity of SCP2 and its potential mechanism for the treatment of AD have yet to be determined. This study used a combination of microbiomics and metabolomics to comprehensively explore the microbiota and metabolic changes in AD rats under SCP2 intervention, with the aim of elucidating the potential mechanisms of SCP2 in the treatment of AD. SCP2 showed significant therapeutic effects in AD rats, as evidenced by improved learning and memory capacity, reduced neuroinflammation, and restoration of the integrity of the intestinal barrier. Fecal metabolomic and microbiomic analyses revealed that SCP2 significantly modulated 19 endogenous metabolites and reversed gut microbiota disorders in AD rats. Moreover, SCP2 significantly increased the content of short-chain fatty acid (SCFAs) in the AD rats. Correlation analysis showed a significant correlation between gut microbes, metabolites and the content of SCFAs. Collectively, these findings will provide the basis for further development of SCP2.

Exploring novel derivatives of isatin-based Schiff bases as multi-target agents: design, synthesis, in vitro biological evaluation, and in silico ADMET analysis with molecular modeling simulations

Recently, scientists developed a powerful strategy called "one drug-multiple targets" to discover vital and unique therapies to fight the most challenging diseases. Novel derivatives of isatin-based Schiff bases 2-7 have been synthesized by the reaction of 3-hydrazino-isatin (1) with aryl aldehydes, hetero-aryl aldehydes, and dialdehydes. The structure of the synthesized derivatives was proved by physical and spectral analysis. Additionally, in vitro biological studies were performed, including antioxidant, anti-diabetic, anti-Alzheimer, and anti-arthritic activities. The four derivatives 3b, 5a, 5b, and 5c possess the highest activities. Among the four potent derivatives, compound 5a exhibited the highest antioxidant (TAC = 68.02 ± 0.15 mg gallic acid per g; IRP = 50.39 ± 0.11) and scavenging activities (ABTS = 53.98 ± 0.12% and DPPH = 8.65 ± 0.02 μg mL-1). Furthermore, compound 5a exhibited an α-amylase inhibitory percentage of 57.64 ± 0.13% near the acarbose (ACA = 69.11 ± 0.15%) and displayed inhibitor activity of the acetylcholinesterase (AChE) enzyme = 36.38 ± 0.08%. Moreover, our work extended to determining the anti-arthritic effect, and compound 5a revealed good inhibitor activities with very close values for proteinase denaturation (PDI) = 39.59 ± 0.09% and proteinase inhibition (PI) = 36.39 ± 0.08%, compared to diclofenac sodium PDI = 49.33 ± 0.11% and PI = 41.88 ± 0.09%. Additionally, the quantum chemical calculations, including HOMO, LUMO, and energy band gap were determined, and in silico ADMET properties were predicted, and their probability was recorded. Finally, molecular docking simulations were performed inside α-amylase and acetylcholinesterase enzymes.

G, Krishnamurthy S, Chaurasia RN, Shrivastava SK. Development and Evaluation of Some Molecular Hybrids of N-(1-Benzylpiperidin-4-yl)-2-((5-phenyl-1,3,4-oxadiazol-2-yl)thio) as Multifunctional Agents to Combat Alzheimer's Disease

A series of some novel compounds (SD-1-17) were designed following a molecular hybridization approach, synthesized, and biologically tested for hAChE, hBChE, hBACE-1, and Aβ aggregation inhibition potential to improve cognition and memory functions associated with Alzheimer's disease. Compounds SD-4 and SD-6 have shown multifunctional inhibitory profiles against hAChE, hBChE, and hBACE-1 enzymes in vitro. Compounds SD-4 and SD-6 have also shown anti-Aβ aggregation potential in self- and acetylcholinesterase (AChE)-induced thioflavin T assay. Both compounds have shown a significant propidium iodide (PI) displacement from the cholinesterase-peripheral active site (ChE-PAS) region with excellent blood-brain barrier (BBB) permeability and devoid of neurotoxic liabilities. Compound SD-6 ameliorates cognition and memory functions in scopolamine- and Aβ-induced behavioral rat models of Alzheimer's disease (AD). Ex vivo biochemical estimation revealed a significant decrease in malonaldehyde (MDA) and AChE levels, while a substantial increase of superoxide dismutase (SOD), catalase, glutathione (GSH), and ACh levels is seen in the hippocampal brain homogenates. The histopathological examination of brain slices also revealed no sign of neuronal or any tissue damage in the SD-6-treated experimental animals. The in silico molecular docking results of compounds SD-4 and SD-6 showed their binding with hChE-catalytic anionic site (CAS), PAS, and the catalytic dyad residues of the hBACE-1 enzymes. A 100 ns molecular dynamic simulation study of both compounds with ChE and hBACE-1 enzymes also confirmed the ligand-protein complex's stability, while quikprop analysis suggested drug-like properties of the compounds.

In vitro enzymatic evaluation of some pyrazolo[1,5-a]pyrimidine derivatives: Design, synthesis, antioxidant, anti-diabetic, anti-Alzheimer, and anti-arthritic activities with molecular modeling simulation

The strategy of utilizing nitrogen compounds in various biological applications has recently emerged as a powerful approach to exploring novel classes of therapeutics to face the challenge of diseases. A series of pyrazolo[1,5-a]pyrimidine-based compounds 3a-l and 5a-f were prepared by the direct cyclo-condensation reaction of 5-amino-1H-pyrazoles 1a, b with 2-(arylidene)malononitriles and 3-(dimethylamino)-1-aryl-prop-2-en-1-ones, respectively. The structures of the new pyrazolo[1,5-a]pyrimidine compounds were confirmed via spectroscopic techniques. The in vitro biological activities of all pyrazolo[1,5-a]pyrimidines 3a-l and 5a-f were evaluated by assaying total antioxidant capacity, iron-reducing power, the scavenging activity against 1-diphenyl-2-picryl-hydrazyl (DPPH) and 2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, anti-diabetic, anti-Alzheimer, and anti-arthritic biological activities. All compounds displayed good to potent bioactivity, and three compounds 3g, 3h, and 3l displayed the most active derivatives. Among these derivatives, compound 3l exhibited the highest antioxidant (total antioxidant capacity [TAC] = 83.09 mg gallic acid/g; iron-reducing power [IRP] = 47.93 µg/ml) and free radicals scavenging activities with (DPPH = 18.77 µg/ml; ABTS = 40.44%) compared with ascorbic acid (DPPH = 4.28 µg/ml; ABTS = 38.84%). Furthermore, compound 3l demonstrated the strongest inhibition of α-amylase with a percent inhibition of 72.91 ± 0.14 compared to acarbose = 67.92 ± 0.09%. Similarly, it displayed acetylcholinesterase inhibition of 62.80 ± 0.06%. However, compound 3i showed a significantly higher inhibition percentage for protein denaturation and proteinase at 20.66 ± 0.00 and 26.42 ± 0.06%, respectively. Additionally, some in silico ADMET properties were predicted and studied. Finally, molecular docking simulation was performed inside the active site of α-amylase and acetylcholinesterase to study their interactions.

Postulating the possible cellular signalling mechanisms of antibody drug conjugates in Alzheimer's disease

Alzheimer's disease (AD) is one of the most common neurodegenerative disorders in the world. Although the basic pathology of the disease is elucidated, it is difficult to restore or prevent the worsening of neurodegeneration and its symptoms. Antibody and small molecule-based approaches have been studied and are in study individually, but a combined approach like conjugation has not been performed to date. The conjugation between antibodies and drugs which are already used for Alzheimer's treatment or developed specifically for this purpose may have better efficacy and dual action in mitigating Alzheimer's disease. A probable mechanism for antibody-drug conjugates in Alzheimer's disease is discussed in the present review.

A Comparative Study between Lycorine and Galantamine Abilities to Interact with AMYLOID β and Reduce In Vitro Neurotoxicity

Galantamine is a natural alkaloid extracted from the Amaryllidaceae plants and is used as the active ingredient of a drug approved for the treatment of the early stages of Alzheimer's disease. It mainly acts as an acetylcholinesterase (AChE) inhibitor, increasing concentrations of the acetylcholine neurotransmitter. Recent cellular studies have also shown the ability of galantamine to protect SH-SY5Y cell lines against amyloid-β (Aβ)-induced toxicity. Such investigations have supported and validated further in-depth studies for understanding the chemical and molecular features associated with galantamine-protective abilities. In addition to galantamine, other natural alkaloids are known to possess AChE inhibitory activity; among them lycorine has been extensively investigated for its antibacterial, anti-inflammatory and antitumoral activities as well. Despite its interesting biological properties, lycorine's neuroprotective functions against Aβ-induced damages have not been explored so far. In this research study, the ability of galantamine and lycorine to suppress Aβ-induced in vitro neuronal toxicity was evaluated by investigating the chemical interactions of the two alkaloids with Aβ peptide. A multi-technique spectroscopic analysis and cellular cytotoxicity assays were applied to obtain new insights on these molecular associations. The comparison between the behaviors exhibited by the two alkaloids indicates that both compounds possess analogue abilities to interact with the amyloidogenic peptide and protect cells.

Preclinical Models for Alzheimer's Disease: Past, Present, and Future Approaches

A robust preclinical disease model is a primary requirement to understand the underlying mechanisms, signaling pathways, and drug screening for human diseases. Although various preclinical models are available for several diseases, clinical models for Alzheimer's disease (AD) remain underdeveloped and inaccurate. The pathophysiology of AD mainly includes the presence of amyloid plaques and neurofibrillary tangles (NFT). Furthermore, neuroinflammation and free radical generation also contribute to AD. Currently, there is a wide gap in scientific approaches to preventing AD progression. Most of the available drugs are limited to symptomatic relief and improve deteriorating cognitive functions. To mimic the pathogenesis of human AD, animal models like 3XTg-AD and 5XFAD are the primarily used mice models in AD therapeutics. Animal models for AD include intracerebroventricular-streptozotocin (ICV-STZ), amyloid beta-induced, colchicine-induced, etc., focusing on parameters such as cognitive decline and dementia. Unfortunately, the translational rate of the potential drug candidates in clinical trials is poor due to limitations in imitating human AD pathology in animal models. Therefore, the available preclinical models possess a gap in AD modeling. This paper presents an outline that critically assesses the applicability and limitations of the current approaches in disease modeling for AD. Also, we attempted to provide key suggestions for the best-fit model to evaluate potential therapies, which might improve therapy translation from preclinical studies to patients with AD.

Probing protein misfolding and dissociation with an infrared free-electron laser

Misfolding is observed in the mutant proteins that are causative for neurodegenerative disorders such as polyglutamine diseases. These proteins are prone to aggregate in the cytoplasm and nucleus of cells. To reproduce cells with the aggregated proteins, gene expression system is usually applied, in which the expression construct having the mutated DNA sequence of the interest is transfected into cells. The transfected DNA is finally converted into the mutant protein, which is gradually aggregated in the cells. In addition, a simple method to prepare the cells having aggregates inside has been recently applied. Peptides were first aggregated by incubating them in water. The aggregates are spontaneously taken up by cells because aggregated proteins generally transfer between cells. Peptides with different degrees of aggregation can be made by changing the incubation times and temperatures, which enables to examine contribution of aggregation to the toxicity to the recipient cells. Moreover, such cells can be used for therapeutic researches of diseases in which aggregates are involved. In this chapter, we show methods to induce aggregation of peptides. The functional analyses of the cells with aggregates are also described. Then, experimental dissociation of the aggregates produced using this method by mid infrared free electron laser irradiation and its theoretical support by molecular dynamics simulation are introduced as the therapeutic research for neurodegenerative disorders.

The Allosteric Antagonist of the Sigma-2 Receptors-Elayta (CT1812) as a Therapeutic Candidate for Mild to Moderate Alzheimer's Disease: A Scoping Systematic Review

Nearly 35 million people worldwide live with Alzheimer's disease (AD). The prevalence of the disease is expected to rise two-fold by 2050. With only symptomatic treatment options available, it is essential to understand the developments and existing evidence that aims to target brain pathology and dementia outcomes. This scoping systematic review aimed to collate existing evidence of CT1812 for use in patients with AD and summarize the methodologies of ongoing trials. Adhering to PRISMA Statement 2020 guidelines, PubMed/MEDLINE, Embase, Cochrane, and ClinicalTrials.gov were systematically searched through up to 15 November 2022 by applying the following keywords: CT1812, Alzheimer's disease, dementia, and/or sigma-2 receptor. Three completed clinical trials were included along with three ongoing records of clinical trials. The three completed trials were in Phases I and II of testing. The sample size across all three trials was 135. CT1812 reached endpoints across the trials and obtained a maximum concentration in the cerebrospinal fluid with 97-98% receptor occupancy. The findings of this systematic review must be used with caution as the results, while mostly favorable so far, must be replicated in higher-powered, placebo-controlled Phase II-III trials.

Kaempferol as a potential neuroprotector in Alzheimer's disease

Alzheimer's disease (AD), the most prevalent neurodegenerative disorder, is largely associated with cognitive disability, amnesia, and abnormal behavior, which accounts for about two third of people with dementia worldwide. A growing body of research demonstrates that AD is connected to several factors, such as aberrant accumulation of amyloid-beta (Aβ), increase in the hyperphosphorylation of Tau protein, and the formation of neurofibrillary tangles, mitochondrial dysfunction, and inordinate production of reactive oxygen species (ROS). Despite remarkable efforts to realize the etiology and pathophysiology of AD, until now, scientists have not developed and introduced medications that can permanently cease the progression of AD. Thus, nowadays, research on the role of natural products in the treatment and prevention of AD has attracted great attention. Kaempferol (KMP), one of the prominent members of flavonols, exerts its ameliorative actions via attenuating oxidative stress and inflammation, reducing Aβ-induced neurotoxicity, and regulating the cholinergic system. Therefore, in this review article, we outlined the possible effects of KMP in the prevention and treatment of AD. PRACTICAL APPLICATIONS: Kaempferol (KMP) exerts its ameliorative actions against AD via attenuating oxidative stress and inflammation, reducing Aβ-induced neurotoxicity, and regulating the cholinergic system. The beneficial effects of KMP were addressed in both in vitro and in vivo studies; however, conducting further research can warrant its long-term effects as a safe agent. Therefore, after confirming its favorable functions in the prevention and treatment of AD, it could be used as a safe and effective agent.