Efficacy of acetylcholinesterase inhibitors in Alzheimer's disease

Recent advances in the therapeutic insights of thiazole scaffolds as acetylcholinesterase inhibitors

Suppression of the acetylcholinesterase (AChE) enzyme is a prevalent strategy for curing diverse mental disorders, including Alzheimer's disease (AD) and the chronic autoimmune disease Myasthenia gravis. Acetylcholinesterase inhibitors promote cholinergic transmission via blocking AChE, which is implicated in the degradation and deficiency of acetylcholine. Various studies proved that the lack of cholinergic neurons in the central nervous system is the substantial reason for the behavioral abnormalities and cognitive retogradation that distinguish mental diseases such as dementia and AD. Moreover, thiazole scaffolds have emerged as prominent pharmacophores in drug discovery owing to their numerous outstanding therapeutic efficacy, comprising anti-acetylcholinesterase efficacy. This review presents various thiazole-based AChE inhibitors in the recent decade. In addition, the various interactions of thiazole derivatives within the active pocket of AChE have been highlighted. Also, structure-activity relationship (SAR) has been discussed.

Innovative bioinspired hydrogel scaffolds enabling in-situ hybrid nanoflower integration for dual-mode acetylcholinesterase inhibitor profiling

This study introduces an innovative bioinspired hydrogel scaffold tailored to facilitate the in-situ integration of hybrid nanoflowers (HNFs) into the sensing interface, thereby establishing a versatile dual-mode platform for the sensitive profiling of acetylcholinesterase (AChE) inhibitors, a pivotal aspect in the pursuit of Alzheimer's disease therapeutics. Mimicking the tenacious anchoring of natural tree roots, our design employs magnetic bead imprinting with Strep-Tactin-coated magnetic beads (STMBs) to shape the hydrogel, which is then complemented by the integration of AChE-specific aptamers. This configuration creates a stable and biomimetic environment that nurtures HNF growth, thereby enhancing the binding integrity of HNFs with sensing interfaces. The platform's dual-mode detection capability, integrating both colorimetric and electrochemical sensing, is demonstrated through the effective evaluation of galantamine's inhibitory potency, with IC50 values that highlight its therapeutic potential. The hydrogel's exceptional reusability, maintaining over 95% of its initial activity after multiple uses, and its long-term stability, retaining 91% of its initial performance, further highlight its practicality and cost-effectiveness. In summary, this bioinspired hydrogel scaffold offers a novel, efficient, and dependable biosensing strategy for HNF-based biosensors, showing great potential for broad applications in medical diagnostics and advanced biosensing technologies.

CRISPR-based epigenetic editing of Gad1 improves synaptic inhibition and cognitive behavior in a Tauopathy mouse model

GABAergic signaling in the brain plays a key role in regulating synaptic transmission, neuronal excitability, and cognitive processes. Large-scale sequencing has revealed the diminished expression of GABA-related genes in Alzheimer's disease (AD), however, it is largely unclear about the epigenetic mechanisms that dysregulate the transcription of these genes in AD. We confirmed that GABA synthesizing enzymes, GAD1 and GAD2, were significantly downregulated in prefrontal cortex (PFC) of AD human postmortem tissues. A tauopathy mouse model also had the significantly reduced expression of GABA-related genes, as well as the diminished GABAergic synaptic transmission in PFC pyramidal neurons. To elevate endogenous Gad1 levels, we used the CRISPR/Cas9-based epigenome editing technology to recruit histone acetyltransferase p300 to Gad1. Cells transfected with a fusion protein consisting of the nuclease-null dCas9 protein and the catalytic core of p300 (dCas9p300), as well as a guide RNA targeting Gad1 promoter (gRNAGad1), had significantly increased Gad1 mRNA expression and histone acetylation at Gad1 promoter. Furthermore, the tauopathy mouse model with PFC injection of dCas9p300 and gRNAGad1 lentiviruses had significantly elevated GABAergic synaptic currents and improved spatial memory. These results have provided an epigenetic editing-based gene-targeting strategy to restore synaptic inhibition and cognitive function in AD and related disorders.

Dimethysiloxane polymer for the effective transdermal delivery of donepezil in Alzheimer's disease treatment

Donepezil (DNZ) has been used to treat dementia associated with mild, moderate, or severe Alzheimer's disease (AD). DNZ uptake can alleviate cognitive symptoms in AD patients via acetylcholinesterase (AChE) inhibition. However, oral administration of DNZ has limitations, including first-pass metabolism, difficulties with swallowing, and low patient compliance. In this work, we disclose a novel transdermal DNZ delivery system utilizing T2 polymer, synthesized via the ring-opening polymerization of 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane with trifluoroacetic acid (TFA). In the in vivo studies in an AD animal model, the DNZ-loaded T2 polymer (DNZ@T2) facilitated efficient transdermal DNZ delivery to the bloodstream and improved spatial working memory and long-term memory of the AD mouse model. Both the T2 polymer and DNZ@T2 exhibited low cytotoxicity and non-significant in vivo toxicity. This research highlights a promising transdermal delivery strategy for AD treatment, potentially enhancing therapeutic efficacy and patient compliance.

Repurposing Drugs: A Promising Therapeutic Approach against Alzheimer's Disease

Alzheimer's disease (AD) is an insidious, irreversible, complex neurodegenerative disorder characterized by progressive cognitive decline and memory loss; affecting millions worldwide. Despite decades of research, no effective disease-modifying treatment exists. However, drug repurposing is a progressive step in identifying new therapeutic uses of existing drugs. It has emerged as a promising strategy in the quest to combat AD. Various classes of repurposed drugs, such as antidiabetic, antihypertensive, antimicrobial, and anti-inflammatory, have shown potential neuroprotective effects in preclinical and clinical studies. These drugs act by combating free radicals generation, neuroinflammation, amyloid-beta aggregation, and tau hyper-phosphorylation. Furthermore, repurposing offers several advantages, including reduced time and cost compared to de novo drug development. It holds immense promise as a complementary approach to traditional drug discovery. Future research efforts should focus on elucidating the underlying mechanisms of repurposed drugs in AD, optimizing drug combinations, and conducting large-scale clinical trials to validate their efficacy and safety profiles. This review overviews recent advancements and findings in preclinical and clinical fields of different repurposed drugs for AD treatment.

Disruption of normal brain distribution of [18F]Nifene to α4β2* nicotinic acetylcholinergic receptors in old B6129SF2/J mice and transgenic 3xTg-AD mice model of Alzheimer's disease: In Vivo PET/CT imaging studies

The 3xTg-AD transgenic mouse model develops Aβ plaque and tau pathology and is purported to closely resemble pathological development in the human Alzheimer's disease (AD) brain. Nicotinic acetylcholine receptors (nAChRs) α4β2* subtype, was studied in this mouse model using [18F]nifene PET/CT and compared with non-transgenic B6129SF2/J mice (male and female). Young 2-month old B6129SF2/J exhibited normal [18F]nifene distribution (measured as standard uptake volume ratios, SUVR with cerebellum as reference) thalamus (TH) 3.12> medial prefrontal cortex (mPFC) 2.33> frontal cortex (FC) 2.06> hippocampus-subiculum (HP-SUB) 1.6. At 11-months of age, B6129SF2/J exhibited high, irreversible and non-saturable [18F]nifene binding in mPFC higher than in TH (mPFC 3.8> TH 2.82> FC 1.79> HP-SUB 1.73). The 3xTg-AD also exhibited high mPFC binding, although the region of highest binding within the mPFC was different compared to B6129SF2/J mice (mPFC 2.44> TH 2.27> FC 1.61> HP-SUB 1.48). [125I]IBETA and immunohistochemistry in 3xTg-AD brain slices confirmed Aβ plaques. The TH of 3xTg-AD mice had lower [18F]nifene binding (reduced by approximately 20 %) compared to both, young and old B6129SF2/J, and was significant. The mPFC [18F]nifene binding was significantly higher in the old B6129SF2/J compared to both the young B6129SF2/J and the 3xTg-AD mice (>150 %). Overall, 3xTg-AD transgenic mice had reduced [18F]nifene binding compared to B6129SF2/J controls, suggesting possible effects of Aβ plaques and Tau on α4β2* nAChRs.

Promising Natural Remedies for Alzheimer's Disease Therapy

This study examines the intricacies of Alzheimer's disease (AD), its origins, and the potential advantages of various herbal extracts and natural compounds for enhancing memory and cognitive performance. Future studies into AD treatments are encouraged by the review's demonstration of the effectiveness of phytoconstituents that were extracted from a number of plants. In addition to having many beneficial effects, such as improved cholinergic and cognitive function, herbal medicines are also much less harmful, more readily available, and easier to use than other treatments. They also pass without difficulty through the blood-brain barrier (BBB). This study focused on natural substances and their effects on AD by using academic databases to identify peer-reviewed studies published between 2015 and 2024. According to the literature review, 66 phytoconstituents that were isolated from 21 distinct plants have shown efficacy, which could be encouraging for future research on AD therapies. Since most clinical trials produce contradictory results, the study suggests that larger-scale studies with longer treatment durations are necessary to validate or refute the therapeutic efficacy of herbal AD treatments.

Novel Soluble Epoxide Hydrolase Inhibitor: Toward Regulatory Preclinical Studies

Neuroinflammation is widely recognized as a key pathological hallmark of Alzheimer's disease (AD). Recently, inhibiting soluble epoxide hydrolase (sEH) has emerged as a promising therapeutic strategy for AD. sEH plays a pivotal role in neuroinflammation by hydrolyzing epoxyeicosatrienoic acids (EETs), which have anti-inflammatory and neuroprotective properties, into pro-inflammatory dihydroepoxyeicosatrienoic acids (DHETs). Furthermore, the overexpression of the enzyme in the brains of AD patients and animal models of the disease highlights its relevance as a therapeutic target. Our previous studies, using the inhibitor UB-SCG-51 demonstrated that sEH inhibition regulates neuroinflammation and other mechanisms, such as the unfolded protein response pathway, while reducing autophagy, apoptosis, and neuronal death, thereby promoting neuroprotection. Building on these findings, we evaluated the arginine salt of the compound, designated UB-SCG-74, which offers improved oral absorption compared to that of UB-SCG-51 while retaining high permeability, potency, and selectivity. In experiments using 5XFAD mice, UB-SCG-74 treatment significantly improved cognition and synaptic plasticity, outperforming donepezil, a standard AD drug, and ibuprofen, an anti-inflammatory drug. Remarkably, these benefits persisted for 4 weeks after administration cessation, suggesting lasting therapeutic effects. Safety pharmacology studies showed no toxicity, supporting the advancement of UB-SCG-74 into preclinical regulatory evaluation. Our findings further indicate that sEH inhibition engages multiple neuroprotective pathways, potentially modifying both AD symptoms and disease progression, thus reinforcing its therapeutic potential.

Pharmacology, toxicology and homeopathy of Luffa operculata (L.) Cogniaux (Cucurbitaceae): Integrative review

Scientific evidence on the pharmacological and toxicological effects of Luffa operculata has been produced on a smaller scale, even though the species: (i) is edible; (ii) widely recognized in folk medicine for treating sinusitis and inducing abortion; (iii) and the basis of allopathic and homeopathic medicines. In this sense, the objective of this review is to characterize the pharmacological, toxicological and clinical profile of products based on L. operculata. After consulting 14 databases, as well as a free search on Google/Google Scholar and checking references, 85 studies were selected that met our eligibility criteria. After analysis and synthesis, we found that the products have a wide range of pharmacological activities in vitro, ex vivo and in vivo. The toxicological spectrum is also alarming in different segments such as: cytogenotoxicity, tissue toxicity, (sub-) acute, reproductive, neuro- and phytotoxicity. The intensity of the pharmacological and toxicological effects is variable, and seems to be conditioned by various factors (examples: plant organ, polarity of the extracting solvent, quantity, experimental model and route of administration). Clinical data show that the products have satisfactory efficacy, tolerability and safety in the treatment of upper airway diseases (especially rhinitis and sinusitis). Finally, we hope that the presentation of toxicological information in this review can guide the safe and rational use of L. operculata in folk medicine. It may also serve as scientific evidence for exploring the pharmacological potential of the species, avoiding its side effects.

Therapeutic Role of Heterocyclic Compounds in Neurodegenerative Diseases: Insights from Alzheimer's and Parkinson's Diseases

Alzheimer's and Parkinson's are the most common neurodegenerative diseases (NDDs). The development of aberrant protein aggregates and the progressive and permanent loss of neurons are the major characteristic features of these disorders. Although the precise mechanisms causing Alzheimer's disease (AD) and Parkinson's disease (PD) are still unknown, there is a wealth of evidence suggesting that misfolded proteins, accumulation of misfolded proteins, dysfunction of neuroreceptors and mitochondria, dysregulation of enzymes, and the release of neurotransmitters significantly influence the pathophysiology of these diseases. There is no effective protective medicine or therapy available even with the availability of numerous medications. There is an urgent need to create new and powerful bioactive compounds since the number of people with NDDs is rising globally. Heterocyclic compounds have consistently played a pivotal role in drug discovery due to their exceptional pharmaceutical properties. Many clinically approved drugs, such as galantamine hydrobromide, donepezil hydrochloride, memantine hydrochloride, and opicapone, feature heterocyclic cores. As these heterocyclic compounds have exceptional therapeutic potential, heterocycles are an intriguing research topic for the development of new effective therapeutic drugs for PD and AD. This review aims to provide current insights into the development and potential use of heterocyclic compounds targeting diverse therapeutic targets to manage and potentially treat patients with AD and PD.

Design, synthesis, and evaluation of novel benzofuran and pyrazole-based derivatives as dual AChE/BuChE inhibitors with antioxidant properties for Alzheimer's disease management

As a complicated neurodegenerative disorder with several clinical hallmarks, Alzheimer's disease (AD) requires multi-target treatment medicines to address multiple elements of disease progression. In this study, we reported two novel series of compounds: benzofuran-based donepezil analogs (9a-i) and their pyrazole-based counterparts (11a-i) as potential dual inhibitors of AChE and BuChE with additional antioxidant properties, aiming to address multiple pathological aspects of AD simultaneously. The design strategy employed bioisosteric replacement, substituting donepezil's indanone motif with a benzofuran ring in series (9a-i) to maintain crucial hydrogen bonding interactions with the Phe295 residue in the enzyme's active site. Subsequently, the benzofuran ring underwent cleavage, yielding pyrazole-tethered hydroxyphenyl derivatives (11a-i). The biological evaluation revealed that benzofuran-based derivative 9g exhibited exceptional efficacy against both AChE and BuChE, with IC50 values of 0.39 and 0.51 μg/ml, respectively, although it lacked antioxidant activity. Compound 11f demonstrated dual inhibition of AChE (IC50 = 1.24 μg/ml) and BuChE (IC50 = 1.85 μg/ml) while also displaying strong DPPH free radical scavenging activity (IC50 = 3.15 μg/ml). In vivo toxicity studies on compound 11f revealed a favorable safety profile, with no signs of toxicity or adverse events in acute oral toxicity tests in male Wistar rats. Chronic administration of 11f resulted in negligible differences in blood profiles, hepatic enzymes, urea, creatinine, and albumin levels compared to the control group. Histopathological examination of hepatic and kidney tissues from treated rats showed normal histology without damage. In silico molecular docking analysis was performed to rationalize the design approaches and support the experimental findings. This study provides valuable insights into the development of multi-target compounds for potential Alzheimer's disease treatment.

Comparative Metabolic Profiling and Biological Evaluation of Essential Oils from Conocarpus Species: Antidiabetic, Antioxidant, and Antimicrobial Potential

Essential oils (EOs) are a diverse source of bioactive compounds with remarkable therapeutic potential. Despite their significance, Conocarpus EOs have been largely underexplored. This study provides a novel comparison of the metabolic profiles and biological activities of EOs from C. lancifolius, C. erectus green, and C. erectus silver leaves cultivated in the United Arab Emirates (UAE), offering unique insights into their distinct bioactive properties and potential therapeutic applications. EOs were extracted via hydro-distillation, analyzed using gas chromatography-mass spectrometry (GC-MS), and subjected to chemometric analysis. Their antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing ability of plasma (FRAP) assays), antidiabetic (α-amylase and α-glucosidase inhibition), acetylcholinesterase (AChE) inhibition and antimicrobial activities were assessed. A total of 92 metabolites were identified, with heptacosane and nonacosane as key species discriminants. C. lancifolius EO showed the strongest α-amylase (IC50 8.75 ± 0.54 µg/mL) and α-glucosidase (IC50 22.31 ± 0.92 µg/mL) inhibitory activities, while C. erectus silver demonstrated superior antioxidant capacity (IC50 349.78 ± 8.26 µg/mL, DPPH assay). C. lancifolius EO exhibited the best antimicrobial activity, particularly against Staphylococcus aureus (MIC 625 µg/mL). C. erectus silver EO inhibited E. coli and C. albicans (MIC 625 µg/mL). In contrast, C. erectus EOs showed no activity against Aspergillus niger. These findings highlight the potential of Conocarpus EOs as antioxidants and for managing diabetes that may be utilized either in nutraceuticals, dietary supplements or even in pharmaceutical formulations. Moreover, owing to significant antimicrobial activities, the EOs may be added to medical disinfectants and several pharmaceutical products. However, further, in vivo validation and pharmaceutical exploration is still needed.

Identifying natural inhibitors against FUS protein in dementia through machine learning, molecular docking, and dynamics simulation

Dementia, a complex and debilitating spectrum of neurodegenerative diseases, presents a profound challenge in the quest for effective treatments. The FUS protein is well at the center of this problem, as it is frequently dysregulated in the various disorders. We chose a route of computational work that involves targeting natural inhibitors of the FUS protein, offering a novel treatment strategy. We first reviewed the FUS protein's framework; early forecasting models using the AlphaFold2 and SwissModel algorithms indicated a loop-rich protein-a structure component correlating with flexibility. However, these models showed limitations, as reflected by inadequate ERRAT and Verify3D scores. Seeking enhanced accuracy, we turned to the I-TASSER suite, which delivered a refined structural model affirmed by robust validation metrics. With a reliable model in hand, our study utilized machine learning techniques, particularly the Random Forest algorithm, to navigate through a vast dataset of phytochemicals. This led to the identification of nimbinin, dehydroxymethylflazine, and several other compounds as potential FUS inhibitors. Notably, dehydroxymethylflazine and cleroindicin C identified during molecular docking analyses-facilitated by AutoDock Vina-for their high binding affinities and stability in interaction with the FUS protein, as corroborated by extensive molecular dynamics simulations. Originating from medicinal plants, these compounds are not only structurally compatible with the target protein but also adhere to pharmacokinetic profiles suitable for drug development, including optimal molecular weight and LogP values conducive to blood-brain barrier penetration. This computational exploration paves the way for subsequent experimental validation and highlights the potential of these natural compounds as innovative agents in the treatment of dementia.

Triple-Target Inhibition of Cholinesterase, Amyloid Aggregation, and GSK3β to Ameliorate Cognitive Deficits and Neuropathology in the Triple-Transgenic Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) poses one of the most urgent medical challenges in the 21st century as it affects millions of people. Unfortunately, the etiopathogenesis of AD is not yet fully understood and the current pharmacotherapy options are somewhat limited. Here, we report a novel inhibitor, Compound 44, for targeting cholinesterases, amyloid-β (Aβ) aggregation, and glycogen synthase kinase 3β (GSK-3β) simultaneously with the aim of achieving symptomatic relief and disease modification in AD therapy. We found that Compound 44 had good inhibitory effects on all intended targets with IC50s of submicromolar or better, significant neuroprotective effects in cell models, and beneficial improvement of cognitive deficits in the triple transgenic AD (3 × Tg AD) mouse model. Moreover, we showed that Compound 44 acts as an autophagy regulator by inducing nuclear translocation of transcription factor EB through GSK-3β inhibition, enhancing the biogenesis of lysosomes and elevating autophagic flux, thus ameliorating the amyloid burden and tauopathy, as well as mitigating the disease phenotype. Our results suggest that triple-target inhibition via Compound 44 could be a promising strategy that may lead to the development of effective therapeutic approaches for AD.

An Expanded Narrative Review of Neurotransmitters on Alzheimer's Disease: The Role of Therapeutic Interventions on Neurotransmission

Alzheimer's disease (AD) is a progressive neurodegenerative disease. The accumulation of amyloid-β (Aβ) plaques and tau neurofibrillary tangles are the key players responsible for the pathogenesis of the disease. The accumulation of Aβ plaques and tau affect the balance in chemical neurotransmitters in the brain. Thus, the current review examined the role of neurotransmitters in the pathogenesis of Alzheimer's disease and discusses the alterations in the neurochemical activity and cross talk with their receptors and transporters. In the presence of Aβ plaques and neurofibrillary tangles, changes may occur in the expression of neuronal receptors which in turn triggers excessive release of glutamate into the synaptic cleft contributing to cell death and neuronal damage. The GABAergic system may also be affected by AD pathology in a similar way. In addition, decreased receptors in the cholinergic system and dysfunction in the dopamine neurotransmission of AD pathology may also contribute to the damage to cognitive function. Moreover, the presence of deficiencies in noradrenergic neurons within the locus coeruleus in AD suggests that noradrenergic stimulation could be useful in addressing its pathophysiology. The regulation of melatonin, known for its effectiveness in enhancing cognitive function and preventing Aβ accumulation, along with the involvement of the serotonergic system and histaminergic system in cognition and memory, becomes remarkable for promoting neurotransmission in AD. Additionally, nitric oxide and adenosine-based therapeutic approaches play a protective role in AD by preventing neuroinflammation. Overall, neurotransmitter-based therapeutic strategies emerge as pivotal for addressing neurotransmitter homeostasis and neurotransmission in the context of AD. This review discussed the potential for neurotransmitter-based drugs to be effective in slowing and correcting the neurodegenerative processes in AD by targeting the neurochemical imbalance in the brain. Therefore, neurotransmitter-based drugs could serve as a future therapeutic strategy to tackle AD.

Assessment of neuroprotective potential of Cuscuta reflexa in aluminium chloride-induced experimental model of Alzheimer's disease: In vitro and in vivo studies

BACKGROUND & AIMS

Cuscuta reflexa (family Convolvulaceae), commonly known as giant dodder or Amarbel, is a parasitic plant that has garnered attention in pharmacological research due to its diverse bioactive compounds and potential therapeutic applications. Scientific studies have validated its traditional uses in folk medicine, highlighting its pharmacological activities. Alzheimer's Disease (AD) is a neurodegenerative disorder marked by the buildup of amyloid-β (Aβ) plaques and neurofibrillary tangles (NFT) in the brain, leading to synaptic impairment and the gradual loss of neurons. Currently, no effective medication is available to treat the development and progression of the disease. Hence, there is a rising concern about using alternative therapy such as herbal medicine to limit the progression of AD and improve the quality of a patient's life with minimum side effects. The plant Cuscuta reflexa has traditionally been claimed to possess neuroprotective effects but has not yet been validated scientifically. The present study aimed to investigate the potential of the hydroalcoholic extract of Cuscuta reflexa (CRE) to ameliorate the neurodegenerative effect of aluminium chloride (AlCl3) using in vitro and in vivo studies.

METHODS

The neuroprotective activity of CRE was evaluated using in vitro and in vivo experimental models of AlCl3-induced AD.

RESULTS

The in vitro study showed that CRE markedly reduced AlCl3-induced cytotoxicity in PC12 cells. The in vivo study using the AlCl3-induced AD rat model showed that CRE treatment improved learning and memory, as evaluated using the open field test (OFT) and Morris water maze (MWM) test. CRE also showed the reduction in oxidative stress induced by AlCl3 in the brains of the rats by virtue of the significant decrease in oxidative stress biomarker malondialdehyde (MDA) and increase in the antioxidant parameters such as reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD). Further, CRE exhibited its cholinergic activity by lowering the AlCl3-induced enhanced levels of acetylcholinesterase (AChE) in the brains of rats. Histopathological analysis of the brains of rats showed that CRE treatment prevented the reactive changes and the damage in the neuronal tissue caused due to the AlCl3.

CONCLUSION

Conclusively, CRE ameliorated AlCl3-induced neurobehavioural toxicity in the rat model of AD by virtue of its anti-inflammatory, antioxidant, cholinergic and neuroprotective effects which suggests its use in the treatment of progressive neural damage and cognitive deficits in AD patients.

Rational design, synthesis, biological evaluation, and molecular modeling of novel naphthamide derivatives possessing potent, reversible, and competitive inhibitory mode of action over human monoamine oxidase

Herein, a novel series of naphthamide derivatives has been rationally developed, synthesized, and evaluated for their inhibitory activity against monoamine oxidase (MAO) and cholinesterase (ChE) enzymes. Compared to the reported naphthalene-based hit IV, the new naphthamide hybrids 2a, 2c, 2g and 2h exhibited promising MAO inhibitory activities; with an IC50 value of 0.294 μM, compound 2c most potently inhibited MAO-A, while compound 2g exhibited most potent MAO-B inhibitory activity with an IC50 value of 0.519 μM. Compounds 2c and 2g showed selectivity index (SI) values of 6.02 for MAO-A and 2.94 for MAO-B, respectively. On the other hand, most compounds showed weak inhibitory activity against ChEs except 2a and 2h over butyrylcholinesterase (BChE). The most potent compounds 2c and 2g were found to be competitive and reversible MAO inhibitors based on kinetic and reversibility studies. Plausible interpretations of the observed biological effects were provided through molecular docking simulations. The drug-likeness predicted by SwissADME and Osiris property explorer showed that the most potent compounds (2a, 2c, 2g, and 2h) obey Lipinski's rule of five. Accordingly, in the context of neurological disorders, hybrids 2c and 2g may contribute to the identification of safe and potent therapeutic approaches in the near future.

Determination of the biological activities of endemic Allium lazikkiyense and its phytochemical profile by LC-MS/MS analysis

This study investigated the phytochemical contents and in vitro antioxidant, enzyme inhibitory and anticancer properties of ethanol, methanol, and dichloromethane extracts prepared from aerial parts and onion peels of endemic Allium lazikkiyense Koçyiğit, Özhatay & E.Kaya. Ethanol extracts showed the highest antioxidant activity among the all extracts in terms of total phenolic and flavonoid contents as well as DPPH scavenging and iron reducing potentials. LC-MS/MS analysis results showed that aerial parts rich in fumaric acid, p-coumaric acid, ascorbic acid and hyperoside while onion peels rich in sarsasapogenin, caffeic acid and fumaric acid. Dichloromethane extracts showed a strong inhibitory effect on α-glucosidase, while all extracts exhibited low inhibitory activity on α-amylase, acetylcholinesterase and butyrylcholinesterase. Also, extracts from onion peels exhibited potent cytotoxic effect against MCF7 human breast cancer cells. The present study revealed that A. lazikkiyense could be a good natural source for antioxidant, α-glucosidase inhibitory, and anticancer activities.

Rg1 improves Alzheimer's disease by regulating mitochondrial dynamics mediated by the AMPK/Drp1 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by a complex pathogenesis that includes Aβ deposition, abnormal phosphorylation of tau protein, chronic neuroinflammation, and mitochondrial dysfunction. In traditional medicine, ginseng is revered as the 'king of herbs'. Ginseng has the effects of greatly tonifying vital energy, strengthening the spleen and benefiting the lungs, generating fluids and nourishing the blood, and calming the mind while enhancing intelligence. Ginsenoside Rg1 (Rg1) is a well-defined major active component found in ginseng, known for its relatively high content. It has been demonstrated to exhibit neuroprotective effects in both in vivo and in vitro models, capable of ameliorating Aβ and tau pathology, regulating synaptic function, and reducing inflammation, oxidative stress, and apoptosis. However, the potential of Rg1 to improve AD pathology through the regulation of mitochondrial dynamics is still uncertain.

AIM OF THE STUDY

Despite the active research efforts on drugs for AD, the currently available anti-AD medications can only slow disease progression and manage symptoms, yet unable to provide a cure for AD. Furthermore, some anti-AD drugs failed phase III and IV clinical trials due to significant side effects. Therefore, there is an urgent need to further investigate the pathogenesis of AD, to identify new therapeutic targets, and to explore more effective therapies. The aim of this study is to evaluate the potential therapeutic effects of Rg1 on APP/PS1 double transgenic mice and Aβ42-induced HT22 cell models, and to investigate the potential mechanisms through which it provides neuroprotective effects.

MATERIALS AND METHODS

This study investigates the effects of Rg1 in treating AD on APP/PS1 double transgenic mice and Aβ42-induced HT22 cells. In the in vivo experiments, APP/PS1 mice were divided into a model group, Rg1-L group, Rg1-H group, and donepezil group, with C57BL/6 mice serving as the control group (n = 12 per group). The Rg1-L and Rg1-H groups were administered Rg1 at doses of 5 mg/kg/d and 10 mg/kg/d, respectively, while the donepezil group received donepezil at a dose of 1.3 mg/kg/d. Both the control and model groups received an equal volume of physiological saline daily for 28 days. Learning and spatial memory were assessed by the Morris water maze (MWM) and novel object recognition (NOR) tests, and neuronal damage by Nissl staining. Aβ deposition was analyzed through immunohistochemistry and Western blot, while the expression levels of synaptic proteins PSD95 and SYN were evaluated via immunofluorescence staining and Western blot. The dendritic spines of neurons was observed by Golgi staining.The ultrastructure of neuronal mitochondria and synapses was examined by transmission electron microscopy (TEM). Mitochondrial function was assessed through measurements of Reactive oxygen species (ROS), Superoxide Dismutase (SOD), and Adenosine Triphosphate (ATP), and Western blot analysis was performed to detect the expression levels of AMPK, p-AMPK, Drp1, p-Drp1, OPA1, Mfn1, and Mfn2, thereby investigating the protective effects of Rg1 on mitochondrial dysfunction and cognitive impairment in APP/PS1 double transgenic mice. In vitro experiments, HT22 cells were treated with Aβ42 of 10 μM for 24 h to verify the therapeutic effects of Rg1. Flow cytometry was used to detect ROS and JC-1, biochemical methods were employed to measure SOD and ATP, immunofluorescence staining was used to detect the expression levels of PSD95 and SYN, and Western blot analysis was conducted to elucidate its potential mechanisms of action.

RESULTS

The findings suggest that after 28 days of Rg1 treatment, cognitive dysfunction in APP/PS1 mice was improved. Pathological and immunohistochemical analyses demonstrated that Rg1 treatment significantly reduced Aβ deposition and neuronal loss. Rg1 can improve synaptic dysfunction and mitochondrial function in APP/PS1 mice. Rg1 activated AMPK, enhanced p-AMPK expression, inhibited Drp1, and reduced p-Drp1 levels, which led to increased expression of OPA1, Mfn1, and Mfn2, thereby inhibiting mitochondrial fission and facilitating mitochondrial fusion. Additionally, Rg1 effectively reversed the decrease in mitochondrial membrane potential (MMP) and the increase in ROS production induced by Aβ42 in HT22 cells, restoring SOD and ATP levels. Furthermore, Rg1 regulated mitochondrial fission mediated by the AMPK/Drp1 signaling pathway, promoting mitochondrial fusion and improving synaptic dysfunction.

CONCLUSION

Our research provides evidence for the neuroprotective mechanisms of Rg1 in AD models. Rg1 modulates mitochondrial dynamics through the AMPK/Drp1 signaling pathway, thereby reducing synaptic and mitochondrial dysfunction in APP/PS1 mice and AD cell models.

Standardized extract of Ginkgo biloba induced memory consolidation in female mice with hypofunction of vesicular acetylcholine transporter

Basal forebrain cholinergic neurons are pivotal for cholinergic signaling in the neocortex and hippocampal formation, crucially implicated in neurodegenerative diseases like late-onset Alzheimer's disease (LOAD), recognition memory impairments, and decision-making. The acetylcholine transporter (VAChT) is essential for loading acetylcholine into synaptic vesicles. Building on our previous findings showing that Ginkgo biloba extract (EGb) preserves recognition memory, we hypothesized EGb would enhance memory in female mice with varying VAChT reductions. We also explored whether reduced cholinergic signaling induces anxiety-like behavior and whether EGb could alleviate such symptoms. Three-month-old female mice with severe VAChT reduction (knockdown homozygotes; VAChT KDHOM), moderate reduction (heterozygotes; VAChT KDHET), and wild-type (WT) mice received the vehicle, 5 mg/kg Donepezil, or EGb at doses of 250, 500, and 1000 mg/kg for 30 days. Memory assessments included aversive tasks like discriminative avoidance memory and non-aversive tasks like object recognition and location memory. We assessed VAChT protein expression in the hippocampal formation (HF) using Western blotting and quantified VAChT-immunopositive cells (IR+) in specific HF subfields (dCA1, dCA3, dDG) using immunohistochemistry. Chronic EGb treatment significantly improved long-term memory in female VAChT KDHOM mice in object recognition and locations memories in a dose-dependent manner, unlike Donepezil. Enhanced memory was correlated with an increase in VAChT-IR+ cells in the dCA1 of VAChT KDHOM mice. Additionally, EGb reduced VAChT-IR+ cells in the dDG of VAChT KDHET mice, which was associated with decreased anxiety-like behavior. These findings suggest that EGb effectively mitigates deficits caused by cholinergic deficiency in hippocampal-dependent memory consolidation, thereby improving our understanding of its role in modulating long-term memory and hippocampal plasticity.

Effects and mechanisms of harmine on ameliorating ethanol-induced memory impairment

ETHNOPHARMACOLOGICAL RELEVANCE

Peganum harmala L., a traditional Uyghur ethnic medicine widely used in China, is commonly used in the treatment of conditions such as hemiplegia, forgetfulness, cough, and asthma. Harmine and other β-carboline alkaloids, one of the main active ingredients in P. harmala, have exhibited various pharmacological activities, including anti-Alzheimer's, antidepressant, anti-inflammatory, and antioxidant effects. However, the effects and underlying mechanisms of harmine on improving ethanol-induced memory impairment remain unclear.

AIM OF THE STUDY

This study aimed to investigate the effects of harmine on ameliorating ethanol-induced memory impairment, and to explore potential mechanisms.

MATERIALS AND METHODS

Ethanol (30%, i. g.) was used to induce memory impairment model. The effect of harmine on memory impairment was evaluated by Morris water maze (MWM). The histopathological analysis, immunofluorescence staining, RT-qPCR and UHPLC-MS/MS methods were performed to further investigate the underlying mechanisms.

RESULTS

MWM experiments showed that harmine significantly improved ethanol-induced spatial learning memory deficit. Harmine exhibited anti-inflammatory effect by downregulating inflammatory factors such as IL-6, IL-1β and tumor necrosis factor-α (TNF-α) induced by ethanol. Harmine also upregulated brain-derived neurotrophic factor (BDNF) levels to exert neuroprotective effect. Moreover, harmine protected neuronal cells and increased the protein expression of myelin basic protein (MBP). The cellular results indicated that harmine protected SH-SY5Y cells from ethanol-induced cytotoxicity and upregulated the relative mRNA expression of synaptosome associated protein 25 (SNAP25), syntaxin 1 A (STX1A), vesicle associated membrane protein 2 (VAMP2), synaptotagmin 1 (SYT1) and synaptophysin (SYP).

CONCLUSIONS

Harmine improved ethanol-induced memory impairment by ameliorating inflammation, increasing BDNF levels, promoting synaptic vesicle fusion, protecting myelin sheath, and modulating neurotransmitter levels. These findings provided a scientific basis for development of therapeutic drugs for alcohol-induced memory impairments and other related disorders.

Multi-target-directed therapeutic strategies for Alzheimer's disease: controlling amyloid-β aggregation, metal ion homeostasis, and enzyme inhibition

Alzheimer's disease (AD) is the most prevalent neurodegenerative dementia, marked by progressive cognitive decline and memory impairment. Despite advances in therapeutic research, single-target-directed treatments often fall short in addressing the complex, multifactorial nature of AD. This arises from various pathological features, including amyloid-β (Aβ) aggregate deposition, metal ion dysregulation, oxidative stress, impaired neurotransmission, neuroinflammation, mitochondrial dysfunction, and neuronal cell death. This review illustrates their interrelationships, with a particular emphasis on the interplay among Aβ, metal ions, and AD-related enzymes, such as β-site amyloid precursor protein cleaving enzyme 1 (BACE1), matrix metalloproteinase 9 (MMP9), lysyl oxidase-like 2 (LOXL2), acetylcholinesterase (AChE), and monoamine oxidase B (MAOB). We further underscore the potential of therapeutic strategies that simultaneously inhibit Aβ aggregation and address other pathogenic mechanisms. These approaches offer a more comprehensive and effective method for combating AD, overcoming the limitations of conventional therapies.

Synthesis, Biological Activities, DFT Calculations, and Molecular Docking Studies of O-Methyl-Inositols

The concise synthesis of O-methyl-d-inositol derivative and conduritol derivatives was obtained starting from p-benzoquinone. Spectroscopic methods have been performed for the characterization of newly synthesized compounds. Cyclitols are useful molecules with anticancer, antibiotic, antinutrient, and antileukemic activities. Inositol class molecules, known as the most important cyclitol derivatives, were examined in this study for their 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide radical scavenging and butyrylcholinesterase (BChE) and glycosidase inhibition activities. It was observed that compound 5, in particular, showed efficacy that competed with the standards in terms of both antioxidant activity and enzyme inhibitor potential. Additionally, compound 5 shows effective antimicrobial activity. The water-soluble characteristics and lipophilic properties of the compounds were also considered and discussed. Moreover, the quantum chemical analyses were performed in light of the DFT/B3LYP/6-311G** level computations to elucidate/compare the studied inositols' possible reactivity directions. Additionally, the interactions of the molecules were analyzed against acetylcholinesterase (AChE), peroxiredoxin 5, and DNA gyrase by molecular docking methods. Cholinesterase inhibitors have an important status as the most important drug group used in the treatment of Alzheimer's disease today. Considering the effects of inhibition of the α-glucosidase enzyme by inhibitors, such molecules can also be used as therapeutic components in the treatment of diabetes.

The Role of Amphibian AMPs Against Oxidative Stress and Related Diseases

Amphibians use their skin as an effective defense mechanism against predators and microorganisms. Specialized glands produce antimicrobial peptides (AMPs) that possess antioxidant properties, effectively reducing reactive oxygen species (ROS) levels. These peptides are promising candidates for treating diseases associated with oxidative stress (OS) and redox imbalance, including neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS), as well as age-related conditions, like cardiovascular diseases and cancer. This review highlights the multifaceted roles of AMPs and antioxidant peptides (AOPs) in amphibians, emphasizing their protective capabilities against oxidative damage. They scavenge ROS, activate antioxidant enzyme systems, and inhibit cellular damage. AOPs often share structural characteristics with AMPs, suggesting a potential evolutionary connection and similar biosynthetic pathways. Peptides such as brevinin-1FL and Cath-KP demonstrate neuroprotective effects, indicating their therapeutic potential in managing oxidative stress-related diseases. The antioxidant properties of amphibian-derived peptides pave the way for novel therapeutic developments. However, a deeper understanding of the molecular mechanisms underlying these peptides and their interactions with oxidative stress is essential to addressing ROS-related diseases and advancing therapeutic strategies in clinical practice.

Biochemical investigation and in silico analysis of the therapeutic efficacy of Ipriflavone through Tet-1 Surface-Modified-PLGA nanoparticles in Streptozotocin-Induced Alzheimer's like Disease: Reduced oxidative damage and etiological Descriptors

Ipriflavone (IPRI), an isoflavone derivative, is clinically used to prevent postmenopausal bone loss in addition to its antioxidant and cognitive benefits. However, its poor aqueous solubility retained its bioavailability. New strategies have been developed to improve the bioavailability and solubility of neurological medications to enhance their potency and limit adverse effects. This study aimed to prepare targeted IPRI-poly-lactic-co-glycolic acid (PLGA) nanoparticles coupled with Tet-1 peptide to increase the therapeutic potency of IPRI in a rat model of Alzheimer's disease (AD). Streptozotocin (STZ) exacerbates Alzheimer-related alterations by promoting central insulin resistance resulted from defective signaling pathways related to neuroinflammation and neurotoxicity. Bilateral intracerebroventricular (icv) injection of STZ was used to introduce the AD model. Icv-STZ injection significantly affected brain insulin, oxidative stress, inflammatory, and apoptotic indicators and caused behavioral abnormalities. STZ promoted the formation of amyloid β42 (Aβ42) by increasing BACE1 and reducing ADAM10 and ADAM17 expression levels. STZ also triggered the accumulation of neurofibrillary tangles and synaptic dysfunction, which are crucial for neurological impairments. Icv-STZ injection showed evident degenerative changes in the pyramidal cell layer and significantly reduced the count of viable cells in both CA1 and prefrontal cortex, indicating increased neuronal cell death. IPRI successfully ameliorated cognitive dysfunction by improving the phosphorylated forms of cAMP-response element-binding protein (pCREB) and extracellular signal-regulated kinase 1/2 (pERK1/2) related to synaptic plasticity. Targeted IPRI nanoparticles exceeded free IPRI potential in reducing oxidative stress, acetylcholinesterase/monoamine oxidase activities, Tau phosphorylation, and Aβ42 levels revealing less degenerative changes and increased viable neuron counts. IPRI-targeted nanoparticles improved the neuroprotective potential of free IPRI, making this strategy applicable to treat many neurodegenerative diseases. Finally, the in silico study predicted its ability to cross the BBB and to bind various protein targets in the brain.

Specific Rosetta-based protein-peptide prediction protocol allows the design of novel cholinesterase inhibitor peptides

The search for novel cholinesterase inhibitors is essential for advancing treatments for neurodegenerative disorders such as Alzheimer's disease (AD). In this study, we employed the Rosetta pepspec module, originally developed for designing peptides targeting protein-protein interactions, to design de novo peptides targeting the peripheral aromatic site (PAS) of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). A total of nine peptides were designed for human AChE (hAChE), T. californica AChE (TcAChE), and human BChE (hBChE). These peptides were synthesized using Fmoc-SPPS and tested in vitro using Ellman's reaction to evaluate their inhibitory potency. Peptide 11tA, designed for TcAChE, exhibited potent inhibition of hAChE (IC50 = 1.21 ± 0.25 µM) and demonstrated strong antioxidant activity against DPPH radicals and lipid peroxidation, making it a promising multitherapeutic candidate for AD. Peptide 11hB, designed for hBChE, showed the highest inhibitory activity against hBChE, with a Ki of 12.69 ± 1.27 µM, making it the most potent natural amino acid peptide reported against hBChE. The computational protocol effectively distinguished the specific characteristics of each enzyme target. Toxicity assessments, including hemolysis tests and A. salina lethality assays, revealed no toxic effects at low concentrations, further supporting the potential of these peptides for peptide-based drug development in AD. This study underscores the growing potential of peptides as alternatives to small-molecule drugs. It demonstrates that computational protocols for protein-protein interactions can be successfully adapted to design high-affinity peptide inhibitors.

Current Status of Plant-Based Bioactive Compounds as Therapeutics in Alzheimer's Diseases

Alzheimer's disease (AD) is a common central neurodegenerative disease disorder characterized primarily by cognitive impairment and non-cognitive neuropsychiatric symptoms that significantly impact patients' daily lives and behavioral functioning. The pathogenesis of AD remains unclear and current Western medicines treatment are purely symptomatic, with a singular pathway, limited efficacy, and substantial toxicity and side effects. In recent years, as research into AD has deepened, there has been a gradual increase in the exploration and application of medicinal plants for the treatment of AD. Numerous studies have shown that medicinal plants and their active ingredients can potentially mitigate AD by regulating various molecular mechanisms, including the production and aggregation of pathological proteins, oxidative stress, neuroinflammation, apoptosis, mitochondrial dysfunction, neurogenesis, neurotransmission, and the brain-gut microbiota axis. In this review, we analyzed the pathogenesis of AD and comprehensively summarized recent advancements in research on medicinal plants for the treatment of AD, along with their underlying mechanisms and clinical evidence. Ultimately, we aimed to provide a reference for further investigation into the specific mechanisms through which medicinal plants prevent and treat AD, as well as for the identification of efficacious active ingredients derived from medicinal plants.

Assessment of greenness, blueness, and whiteness profiles of a validated HPLC-DAD method for quantitation of Donepezil HCl and Curcumin in their laboratory prepared co-formulated nanoliposomes

White and Green Analytical Chemistry are innovative approaches in analytical chemistry that prioritize both sustainability and efficiency. Together, these approaches aim to advance scientific research while minimizing environmental impact and enhancing safety. This integration of environmental consciousness into analytical practices represents a significant step forward in achieving sustainable scientific progress. In the present study, a sensitive eco-friendly HPLC-DAD method was carried out and validated to allow concurrent determination of Donepezil HCl (DPZ) and Curcumin (CUR) in their pure form and laboratory made nano-liposome formulation. Optimum seperation was accomplished by utilising Zobrax Eclipse Plus C18 column (4.6*100 mm,5 μm) with gradient elution of the mobile phase composed of 0.02 M phosphate buffer at pH 3.2 and ethanol at flow rate of 1.5 ml/min. A diode array detector (DAD) was implemented for detection at 273 nm and 435 nm for DPZ and CUR, respectively, with the column oven set at 40 °C. The method was validated according to ICH specifications in terms of accuracy, precision, linearity range, detection and quantification limit. The calibration plots were linear with correlation coefficients (r2) = 0.999 over the range (0.1-100 µg/ml) and (0.1-100 µg/ml) for DPZ and CUR, successively. The validated HPLC-DAD approach was adopted to analyse both medications in laboratory prepared nano-liposomal formulation in which the analytes were successfully quantified with good recovery values and no disrubtion from the added excipients. The investigation of whiteness, blueness, and greenness metrics revealed a major benefit of the suggested approach over previous reported ones.

Evolution of Alzheimer's Disease Therapeutics: From Conventional Drugs to Medicinal Plants, Immunotherapy, Microbiotherapy and Nanotherapy

Alzheimer's disease (AD) represents an escalating global health crisis, constituting the leading cause of dementia among the elderly and profoundly impairing their quality of life. Current FDA-approved drugs, such as rivastigmine, donepezil, galantamine, and memantine, offer only modest symptomatic relief and are frequently associated with significant adverse effects. Faced with this challenge and in line with advances in the understanding of the pathophysiology of this neurodegenerative condition, various innovative therapeutic strategies have been explored. Here, we review novel approaches inspired by advanced knowledge of the underlying pathophysiological mechanisms of the disease. Among the therapeutic alternatives, immunotherapy stands out, employing monoclonal antibodies to specifically target and eliminate toxic proteins implicated in AD. Additionally, the use of medicinal plants is examined, as their synergistic effects among components may confer neuroprotective properties. The modulation of the gut microbiota is also addressed as a peripheral strategy that could influence neuroinflammatory and degenerative processes in the brain. Furthermore, the therapeutic potential of emerging approaches, such as the use of microRNAs to regulate key cellular processes and nanotherapy, which enables precise drug delivery to the central nervous system, is analyzed. Despite promising advances in these strategies, the incidence of Alzheimer's disease continues to rise. Therefore, it is proposed that achieving effective treatment in the future may require the integration of combined approaches, maximizing the synergistic effects of different therapeutic interventions.

Neuroprotective Potential of Origanum majorana L. Essential Oil Against Scopolamine-Induced Memory Deficits and Oxidative Stress in a Zebrafish Model

Origanum majorana L., also known as sweet marjoram, is a plant with multiple uses, both in the culinary field and traditional medicine, because of its major antioxidant, anti-inflammatory, antimicrobial, and digestive properties. In this research, we focused on the effects of O. majorana essential oil (OmEO, at concentrations of 25, 150, and 300 μL/L), evaluating chemical structure as well as its impact on cognitive performance and oxidative stress, in both naive zebrafish (Danio rerio), as well as in a scopolamine-induced amnesic model (SCOP, 100 μM). The fish behavior was analyzed in a novel tank-diving test (NTT), a Y-maze test, and a novel object recognition (NOR) test. We also investigated acetylcholinesterase (AChE) activity and the brain's oxidative stress status. In parallel, we performed in silico predictions (research conducted using computational models) of the pharmacokinetic properties of the main compounds identified in OmEO, using platforms such as SwissADME, pKCSM, ADMETlab 2.0, and ProTox-II. The results revealed that the major compounds were trans-sabinene hydrate (36.11%), terpinen-4-ol (17.97%), linalyl acetate (9.18%), caryophyllene oxide (8.25%), and α-terpineol (6.17%). OmEO can enhance memory through AChE inhibition, reduce SCOP-induced anxiety by increasing the time spent in the top zone in the NTT, and significantly reduce oxidative stress markers. These findings underscore the potential of using O. majorana to improve memory impairment and reduce oxidative stress associated with cognitive disorders, including Alzheimer's disease (AD).

Untangling the complex mechanisms associated with Alzheimer's disease in elderly patients using high-throughput RNA sequencing data and next-generation knowledge discovery methods: Focus on potential gene signatures and drugs for dementia

Objectives

Alzheimer's disease (AD) is a complex neurodegenerative disorder that primarily affects elderly individuals. This study aimed to elucidate the intricate mechanisms underlying AD in elderly patients compared with healthy aged individuals using high-throughput RNA sequencing (RNA-seq) data and next-generation knowledge discovery methods (NGKD), with a focus on identifying potential therapeutic agents.

Methods

High-throughput RNA-seq data were obtained from the Gene Expression Omnibus (GEO) database (accession number: GSE104704). These data were derived from healthy and diseased human brains (eight young healthy brains [young], 10 aged healthy brains [Old], and 12 aged diseased brains [AD]). We used NGKD tools such as GEO RNA-seq Experiments Interactive Navigator (GREIN) to obtain differentially expressed genes (DEGs) by comparing the AD versus Old RNA-seq data and further filtered and normalized to obtain differentially regulated Kyoto Encyclopedia of Genes and Genomes (KEGG), Reactome and Panther pathways using ExpressAnalyst tool. Besides, WebGestalt was used to identify differentially regulated Gene Ontologies (GO) and the pre-ranked Gene Set Enrichment Analysis (GSEA) was performed using GSEA software. The X2K web tool was used to infer upstream regulator networks and X2K Appyter tool for obtaining transcription factors (TFs) and kinase network information. LFW1000 and L1000CDS2 tools were used to identify specific drugs that reverse AD-associated gene signatures in elderly patients.

Results

Our study revealed significant downregulation of pathways related to neuroactive receptor-ligand interaction, synaptic vesicle cycle, and neuronal system in elderly individuals with AD. GO analysis showed negative enrichment of functions related to cognition, potassium ion transport, receptor-ligand activity, SNARE binding, and primary lysosomes. The transcription factors SUZ12 and REST, along with increased MAPK signaling, were identified as key regulators of downregulated genes. Several drugs and natural products, including dihydroergocristine, mepacrine, gedunin, amlodipine, and disulfiram have been identified as potential therapeutic agents for reversing AD-associated gene signatures.

Conclusions

This comprehensive analysis of AD in elderly individuals using RNA-seq data and NGKD tools revealed multiple differentially regulated pathways, gene signatures, and potential drugs for dementia treatment. These findings highlight the complex molecular mechanisms underlying AD and provide insights into potential therapeutic strategies. Further research is needed to validate these findings and to develop personalized treatment approaches for AD in elderly patients.

Enhancement of Cognitive Benefits and Anti-Anxiety Effects of Phytolacca americana Fruits in a Zebrafish (Danio rerio) Model of Scopolamine-Induced Memory Impairment

Phytolacca americana fruits exhibit a wide range of biological activities, including antimicrobial, anti-inflammatory, and anticancer properties. This study aims to investigate the phenolic profile of hydroethanolic extracts from both fresh (PEC) and dried (PEU) fruits of P. americana using high-performance liquid chromatography (HPLC) and to evaluate their impact on anxiety-like behavior, memory, oxidative stress, and cholinergic status in zebrafish (Danio rerio, Tübingen strain) treated with scopolamine (SCO, 100 μM). Acute administration of PEC and PEU (0.1, 0.5, and 1 mg/L) was conducted for one hour per day. In silico analyses were performed to evaluate the pharmacokinetic characteristics of the phenolic compounds discerned in the two extracts, using platforms such as SwissAdme, Molinspiration, ProToX-III, AdmetLab 3.0, PKCSM, and PASS. Anxiety-like behavior and memory performance were assessed through specific behavioral assays, including the novel tank test (NTT), light/dark test (LD), novel approach test (NAT), Y-maze, and novel object recognition (NOR). Subsequently, the activity of acetylcholinesterase (AChE) and the extent of oxidative stress in the zebrafish brain were investigated. Our findings suggest that both PEC and PEU possess anxiolytic effects, alleviating SCO-induced anxiety and enhancing cognitive performance in amnesic zebrafish. Furthermore, these extracts demonstrated the ability to mitigate cholinergic deficits by inhibiting AChE activity and supporting antioxidant defense mechanisms through increased activity of antioxidant enzymes and reduced lipid and protein peroxidation. These results highlight the potential use of P. americana fruit extracts in managing anxiety and cognitive impairments related to dementia conditions.

Evaluating Quinolines: Molecular Dynamics Approach to Assess Their Potential as Acetylcholinesterase Inhibitors for Alzheimer's Disease

Quinoline represents a promising scaffold for developing potential drugs because of the wide range of biological and pharmacological activities that it exhibits. In the present study, quinoline derivatives obtained from CADMA-Chem docking protocol were investigated in the mean of molecular dynamics simulations as potential inhibitors of acetylcholinesterase enzyme. The examined species can be partitioned between neutral, dq815 (2,3 dihydroxyl-quinoline-4-carbaldehyde), dq829 (2,3 dihydroxyl-quinoline-8-carboxylic acid methane ester), dq1356 (3,4 dihydroxyl-quinoline-6-carbaldehyde), dq1368 (3,4 dihydroxyl-quinoline-8-carboxylic acid methane ester) and dq2357 (5,6 dihydroxyl-quinoline-8-carboxylic acid methane ester), and deprotonated, dq815_dep, dq829_dep, dq1356_dep and dq2357_dep. Twelve molecular dynamics simulations were performed including those of natural acetylcholine, of the well-known donepezil inhibitor and of the founder quinoline chosen as reference. Key intermolecular interactions were detected and discussed to describe the different dynamic behavior of all the considered species. Binding energies calculation from MMPBSA well accounts for the dynamic behavior observed in the simulation time proposing dq1368 as promising candidate for the inhibition of acetylcholinesterase. Retrosynthetic route for the production of the investigated compounds is also proposed.

Frontiers of Neurodegenerative Disease Treatment: Targeting Immune Cells in Brain Border Regions

Neurodegenerative diseases (NDs) demonstrate a complex interaction with the immune system, challenging the traditional view of the brain as an "immune-privileged" organ. Microglia were once considered the sole guardians of the brain's immune response. However, recent research has revealed the critical role of peripheral immune cells located in key brain regions like the meninges, choroid plexus, and perivascular spaces. These previously overlooked cells are now recognized as contributors to the development and progression of NDs. This newfound understanding opens doors for pioneering therapeutic strategies. By targeting these peripheral immune cells, we may be able to modulate the brain's immune environment, offering an alternative approach to treat NDs and circumvent the challenges posed by the blood-brain barrier. This comprehensive review will scrutinize the latest findings on the complex interactions between these peripheral immune cells and NDs. It will also critically assess the prospects of targeting these cells as a ground-breaking therapeutic avenue for these debilitating disorders.

Daidzein's potential in halting neurodegeneration: unveiling mechanistic insights

Neurological conditions encompassing a wide range of disorders pose significant challenges globally. The complex interactions among signaling pathways and molecular elements play pivotal roles in the initiation and progression of neurodegenerative diseases. Isoflavones have emerged as a promising candidate to fight against neurodegenerative diseases. Daidzein, a 7-hydroxy-3-(4-hydroxyphenyl)-chromen-4-one, belongs to the isoflavone class and exhibits a diverse pharmacological profile. It is found primarily in soybeans and soy products, as well as in some other legumes and herbs. Investigations into daidzein have revealed that it confers neuroprotection by inhibiting oxidative stress, inflammation, and apoptosis, which are key contributors to neuronal damage and degeneration. Activating pathways like PI3K/Akt/mTOR and promoting neurotrophic factors like BDNF by daidzein underscore its potential in supporting neuronal function and combating neurodegeneration. Daidzein's effects on dopamine provide further avenues for intervention in conditions like Parkinson's disease. Additionally, the modulation of inflammatory and NRF-2-antioxidant signaling by daidzein reinforces its neuroprotective role. Moreover, daidzein's interaction with receptors and cellular processes like ER-β, GPR30, MAO, VEGF, and GnRH highlights its multifaceted effects across multiple pathways involved in neuroprotection and neuronal function. This review article delves into the mechanistic interplay of various mediators in mediating the neuroprotective effects of daidzein. The review article consolidates and analyzes research published over nearly two decades (2005-2024) from various databases, including PubMed, Scopus, ScienceDirect, and Web of Science, to provide a comprehensive understanding of daidzein's effects and mechanisms in neuroprotection.

Chitosan nanoparticle-mediated nose-to-brain delivery of naringenin: Attenuating memory decline in experimental animals via behavioural assessment and modulation of biochemical parameters

Naringenin, a flavonoid with potent antioxidant properties, faces low bioavailability, limiting its clinical application in Alzheimer's disease. This study developed naringenin-loaded chitosan nanoparticles (NAR-CNPs) for nose-to-brain delivery using the ionic gelation method. The NAR-CNPs exhibited an average particle size of 112.35 ± 1.55 nm, zeta potential of 15.36 ± 2.05 mV, and entrapment efficiency of 69.49 ± 1.88 %, with a sustained release profile (65.80 % over 8 h). Ex vivo permeation studies showed a 1.91-fold higher steady-state flux for NAR-CNPs compared to naringenin suspension, indicating enhanced brain penetration. The NAR-CNPs were safe for goat nasal mucosa and improved cognitive function in scopolamine-induced demented mice, whereas significantly reducing acetylcholinesterase activity (p < 0.001) and increasing antioxidant enzyme activities in the brain of experimental mice. Concurrently, the level of malondialdehyde was decreased in the brain, indicating reduced lipid peroxidation. Histopathological analysis showed a significant increase in neuronal count in NAR-CNPs treated animals compared to control group. These findings suggest that intranasally administered NAR-CNPs hold promise for treating cognitive impairment, though further studies are needed for clinical translation.

Neuroprotective Potential of Indole-Based Compounds: A Biochemical Study on Antioxidant Properties and Amyloid Disaggregation in Neuroblastoma Cells

Based on the established neuroprotective properties of indole-based compounds and their significant potential as multi-targeted therapeutic agents, a series of synthetic indole-phenolic compounds was evaluated as multifunctional neuroprotectors. Each compound demonstrated metal-chelating properties, particularly in sequestering copper ions, with quantitative analysis revealing approximately 40% chelating activity across all the compounds. In cellular models, these hybrid compounds exhibited strong antioxidant and cytoprotective effects, countering reactive oxygen species (ROS) generated by the Aβ(25-35) peptide and its oxidative byproduct, hydrogen peroxide, as demonstrated by quantitative analysis showing on average a 25% increase in cell viability and a reduction in ROS levels to basal states. Further analysis using thioflavin T fluorescence assays, circular dichroism, and computational studies indicated that the synthesized derivatives effectively promoted the self-disaggregation of the Aβ(25-35) fragment. Taken together, these findings suggest a unique profile of neuroprotective actions for indole-phenolic derivatives, combining chelating, antioxidant, and anti-aggregation properties, which position them as promising compounds for the development of multifunctional agents in Alzheimer's disease therapy. The methods used provide reliable in vitro data, although further in vivo validation and assessment of blood-brain barrier penetration are needed to confirm therapeutic efficacy and safety.

Genetically Engineered Mouse Models for Alzheimer Disease and Frontotemporal Dementia: New Insights from Single-Cell and Spatial Transcriptomics

Neurodegenerative diseases, including Alzheimer disease, frontotemporal dementia, Parkinson disease, Huntington disease, and amyotrophic lateral sclerosis, are often casually linked to protein aggregation and inclusion. As the origins of those proteinopathies have been biochemically traced and genetically mapped, genetically engineered animal models carrying the specific mutations or variants are widely used for investigating the etiology of these diseases, as well as for testing potential therapeutics. This article focuses on the mouse models of Alzheimer disease and closely related frontotemporal dementia, particularly the ones that have provided most valuable knowledge, or are in a trajectory of doing so. More importantly, some of the major findings from these models are summarized, based on the recent single-cell transcriptomics, multiomics, and spatial transcriptomics studies. While no model is perfect, it is hoped that the new insights from these models and the practical use of these models will continue to help to establish a path forward.

Biological Implications of the Intrinsic Deformability of Human Acetylcholinesterase Induced by Diverse Compounds: A Computational Study

The enzyme acetylcholinesterase (AChE) plays a crucial role in the termination of nerve impulses by hydrolyzing the neurotransmitter acetylcholine (ACh). The inhibition of AChE has emerged as a promising therapeutic approach for the management of neurological disorders such as Lewy body dementia and Alzheimer's disease. The potential of various compounds as AChE inhibitors was investigated. In this study, we evaluated the impact of natural compounds of interest on the intrinsic deformability of human AChE using computational biophysical analysis. Our approach incorporates classical dynamics, elastic networks (ENM and NMA), statistical potentials (CUPSAT and SWOTein), energy frustration (Frustratometer), and volumetric cavity analyses (MOLE and PockDrug). The results revealed that cyanidin induced significant changes in the flexibility and rigidity of AChE, especially in the distribution and volume of internal cavities, compared to model inhibitors such as TZ2PA6, and through a distinct biophysical-molecular mechanism from the other inhibitors considered. These findings suggest that cyanidin could offer potential mechanistic pathways for future research and applications in the development of new treatments for neurodegenerative diseases.

Metabolic Activation and Cytotoxicity of Donepezil Induced by CYP3A4

Donepezil (DNP) is a selective cholinesterase inhibitor widely used for the therapy of Alzheimer's disease. Instances of liver injury correlated with DNP treatment have been reported, yet the underlying hepatotoxic mechanism remains to be elucidated. This study aimed to explore the contribution of metabolic activation to the hepatotoxicity of DNP. The structure of 6-O-desmethyl DNP (M1), the oxidative metabolite of DNP, was characterized by chemical synthesis, LC-MS/MS, and nuclear magnetic resonance. A reactive quinone methide resulting from the metabolism of DNP was captured by glutathione (GSH) fortified in liver microsomal incubations after exposure to DNP, and the resulting GSH conjugate (M2) was detected in the bile of rats receiving DNP. Recombinant human P450 enzyme incubation studies demonstrated that CYP3A4 was the principal enzyme responsible for the production of M1 and M2. The generation of M2 declined in rat primary hepatocytes pretreated with ketoconazole, an inhibitor of CYP3A4, which also decreased the vulnerability of rat primary hepatocytes to DNP-caused cytotoxicity. These findings suggest that the quinone methide metabolite may contribute to the cytotoxicity and hepatotoxicity caused by the DNP.

Cholinesterase Inhibitory Activity and Molecular Docking Studies of Isocryptolepine-Triazole Adducts

Due to the rising prevalence of Alzheimer's disease (AD), there is a pressing need for more effective drugs to treat or manage AD's symptoms. Studies have shown that cholinesterase inhibition can improve cognitive and behavioral symptoms associated with AD, by addressing the cholinergic deficit. Based on the recent development of cholinesterase inhibitors with indoloquinoline and triazole moiety, we rationalized that compounds with an isocryptolepine-triazole scaffold may also have the same biological targets. In this study, eighteen previously synthesized isocryptolepine-triazole compounds were assessed for their ability to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The majority of these compounds demonstrated potent selective AChE inhibition. Furthermore, our molecular docking and molecular dynamic simulation studies reveal that the isocryptolepine and triazole moieties are important for the binding of the compounds with the periphery of the AChE's binding pocket. While reductions in molecular weights and lipophilicities may be necessary to improve their pharmacokinetic properties, this work provides valuable insights for designing future AChE inhibitors, based on the novel isocryptolepine-triazole scaffold.

Advancing the Validation of the Enrichment-Enhanced Detection Strategy with Au Nanoclusters for AChE Detection

High-sensitivity fluorescent probes provide a powerful tool for understanding life processes and functioning mechanisms. Therefore, the development of a universal strategy to optimize probes holds substantial importance. Herein, we developed a novel strategy for common probe upgrades: rather than simply pursuing a higher fluorescence intensity of the probe itself, we tried to promote the detection sensitivity by enhancing the probe-substrate interactions. Fortified with polyionic polymers, self-assembled probes could be endowed with enhanced attractions to the substrate. In this work, we took the AChE-AuNCs detection system as a typical and important example to verify this concept of the "enrichment-enhanced detection" strategy (EED strategy). Two probes, AuNCs@GC and AuNCs@CMCS, with similar composing polymers (chitosan derivatives), microstructures, fluorescence profiles, and distinct charges were delicately designed and thoroughly studied. CMCS with an abundance of negatively charged carboxy groups plays an important role in the enrichment of thiocholine through electrostatic interactions. Thus, despite having similar composing components, structures, and almost identical fluorescence profiles, the negatively charged composite shows superior sensitivity (15.2-fold enhancement) and response time (2-fold faster) compared to the AuNCs@GC, thereby validating the feasibility of the EED strategy. Overall, our work validates the EED strategy and applies it to the accurate detection of AChE activity. We believe that this strategy offers substantial insights for the generalization and enhancement of advanced nanoprobes.

The effect of acetylcholinesterase inhibitor rivastigmine in pentylenetetrazole-induced kindling model of epilepsy in rats

This study aimed to investigate the role of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitor rivastigmine (RIVA) in the pentylenetetrazole (PTZ)- induced kindling model of epilepsy. The current study consists of three steps; 1) Saline or RIVA (0.5, 1, and 2 mg/kg) was administered intraperitoneally (i.p.) 15 min before PTZ (35 mg/kg) during the kindling process and seizure behaviors were observed; 2) Single doses of RIVA (0.25, 0.5, and 1 mg/kg; i.p.) was administered to the electrode implanted kindled rats 15 min before PTZ and electrocorticogram (ECoG) recordings were obtained; 3) Low-dose of RIVA (0.5 mg/kg) was administered to the kindled rats for 14 consecutive days and after 24 h PTZ was administered and ECoG recordings were obtained. In addition, 24 h after the PTZ injection, the hippocampus was extracted and mRNA expression levels of N-methyl D-aspartate receptor subunit 2B (NR2B) and brain-derived neurotrophic factor (BDNF) were measured by qPCR analysis. Only low-dose of RIVA increased resistance against kindling. Single and long-term administration of low-dose RIVA increased the latency to the first myoclonic jerk, decreased the duration of generalized tonic-clonic seizures, and reduced the seizure stage in kindled rats. Long-term low-dose RIVA treatment decreased the mRNA expressions of NR2B and BDNF, which were increased after PTZ kindling. Low-dose of RIVA showed anticonvulsant properties, while high doses did not. RIVA exerts its anticonvulsant effect probably through NMDAR-BDNF pathways. Our results suggest that the use of RIVA may not be harmful and even reduce seizure severity in epileptic patients with convulsions.

Nanotechnology used for siRNA delivery for the treatment of neurodegenerative diseases: Focusing on Alzheimer's disease and Parkinson's disease

Neurodegenerative diseases (ND) are often accompanied by dementia, motor dysfunction, or disability. Caring for these patients imposes a significant psychological and financial burden on families. Until now, there are no effective methods for the treatment of NDs. Among them, Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most common. Recently, studies have revealed that the overexpression of certain genes may be linked to the occurrence of AD and PD. Small interfering RNAs (siRNAs) are a powerful tool for gene silencing because they can specifically bind to and cleave target mRNA. However, the intrinsic properties of naked siRNA and various physiological barriers limit the application of siRNA in the brain. Nanotechnology is a promising option for addressing these issues. Nanoparticles are not only able to protect siRNA from degradation but also have the advantage of crossing various physiological barriers to reach the brain target of siRNA. In this review, we aim to introduce diverse nanotechnology used for delivering siRNA to treat AD and PD. Finally, we will briefly discuss our perspectives on this promising field.

Glutamate: Molecular Mechanisms and Signaling Pathway in Alzheimer's Disease, a Potential Therapeutic Target

Gamma-glutamate is an important excitatory neurotransmitter in the central nervous system (CNS), which plays an important role in transmitting synapses, plasticity, and other brain activities. Nevertheless, alterations in the glutamatergic signaling pathway are now accepted as a central element in Alzheimer's disease (AD) pathophysiology. One of the most prevalent types of dementia in older adults is AD, a progressive neurodegenerative illness brought on by a persistent decline in cognitive function. Since AD has been shown to be multifactorial, a variety of pharmaceutical targets may be used to treat the condition. N-methyl-D-aspartic acid receptor (NMDAR) antagonists and acetylcholinesterase inhibitors (AChEIs) are two drug classes that the Food and Drug Administration has authorized for the treatment of AD. The AChEIs approved to treat AD are galantamine, donepezil, and rivastigmine. However, memantine is the only non-competitive NMDAR antagonist that has been authorized for the treatment of AD. This review aims to outline the involvement of glutamate (GLU) at the molecular level and the signaling pathways that are associated with AD to demonstrate the drug target therapeutic potential of glutamate and its receptor. We will also consider the opinion of the leading authorities working in this area, the drawback of the existing therapeutic strategies, and the direction for the further investigation.

Behavioral neuroscience in zebrafish: unravelling the complexity of brain-behavior relationships

This paper reviews the utility of zebrafish (Danio rerio) as a model system for exploring neurobehavioral phenomena in preclinical research, focusing on physiological processes, disorders, and neurotoxicity biomarkers. A comprehensive review of the current literature was conducted to summarize the various behavioral characteristics of zebrafish. The study examined the etiological agents used to induce neurotoxicity and the biomarkers involved, including Aβ42, tau, MMP-13, MAO, NF-Кβ, and GFAP. Additionally, the different zebrafish study models and their responses to neurobehavioral analysis were discussed. The review identified several key biomarkers of neurotoxicity in zebrafish, each impacting different aspects of neurogenesis, inflammation, and neurodegeneration. Aβ42 was found to alter neuronal growth and stem cell function. Tau's interaction with tubulin affected microtubule stability and led to tauopathies under pathological conditions. MMP-13 was linked to oxidative assault and sensory neuron degeneration. MAO plays a role in neurotransmitter metabolism and neurotoxicity conversion. NF-Кβ was involved in pro-inflammatory pathways, and GFAP was indicative of neuroinflammation and astroglial activation. Zebrafish provide a valuable model for neurobehavioral research, adhering to the "3Rs" philosophy. Their neurotoxicity biomarkers offer insights into the mechanisms of neurogenesis, inflammation, and neurodegeneration. This model system aids in evaluating physiological and pathological conditions, enhancing our understanding of neurobehavioral phenomena and potential therapeutic interventions.

Nanodisc-associated acetylcholinesterase as a novel model system of physiological relevant membrane-bound cholinesterases. Inhibition by phenolic compounds

Acetylcholinesterase (AChE) plays a pivotal role in the cholinergic system, and its inhibition is sought after in a wide range of applications, from insect control to Alzheimer's disease treatment. While the primary physiological isoforms of AChE are membrane-bound proteins, most assays for discovering new, safer, and potent inhibitors are conducted using commercially available soluble isoforms, such as the electric eel AChE (eeAChE). In this study, we conducted a comparative analysis of the activity and selectivity to phenolic inhibitors of recombinant human AChE, eeAChE and a mutant variant of human AChE known as dAChE4. Despite numerous mutations, dAChE4 closely resembles its parental protein and serves as a suitable model for monomeric human AChE. We also established an in vitro system of membrane-bound AChE to create a model that closely mimics the physiological isoforms. This system ensures the proper work of the enzyme and allowed us to control the exact concentration of enzyme and lipids per assay.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate)-based microspheres as a sustained platform for Huperzine A delivery for alzheimer's disease therapy

Huperzine A (HupA) is used in Alzheimer's disease (AD) therapy for its effective inhibition of acetylcholinesterase (AChE) and enhancement of cholinergic neuronal function. However, direct oral administration and injection of HupA cause side effects like nausea, anorexia, and rapid metabolism. Using a tripolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate (PBVHx), from the polyhydroxyalkanoate (PHA) family synthesized via synthetic biology, we present a novel AD therapy strategy with peritoneally administered PBVHx microspheres loaded with HupA (HupA-PBVHxMs). This approach extends HupA's metabolic duration in the blood and brain, enhancing AChE inhibition efficacy. Uniformly sized HupA-PBVHxMs, created using microfluidics and rotary evaporation, show up to 70.4 % drug encapsulation efficiency, sustained HupA release for 40 days, reduced neurotoxicity from Aβ25-35, and maintained in vivo HupA supply and AChE inhibition for over 20 days. In cognitive tests, HupA-PBVHxMs improved function in AD mice. Thus, PBVHx microspheres with slower HupA release and lower biotoxicity offer a superior platform for sustained AChE inhibitor release, outperforming commercial PLGA microspheres.