Oxidative Stress and β-Amyloid Protein in Alzheimer’s Disease

Ameliorative potential of ethanol extract of Calyptrochilum emarginatum leaves on scopolamine-induced amnesia in male swiss mice

ETHNOPHARMACOLOGICAL RELEVANCE

Calyptrochilum emarginatum (Afzel. Ex Sw.) Schltr. (Orchidaceae) is a traditional medicinal plant known for its antimicrobial properties and efficacy in managing convulsive fever and menstrual disorders and addressing conditions such as malaria, tuberculosis, and cough.

AIM OF THE STUDY

The study aims to examine the memory-enhancing and neuroprotective properties of ethanol extract of Calyptrochilum emarginatum leaves (EECEL) in scopolamine-induced amnesia mice model.

MATERIALS AND METHODS

Forty-two male mice were divided into six groups (n = 7). Group 1 served as control, administered distilled water (10 mL/kg, p. o), group 2 received scopolamine only (3 mg/kg, i. p.), groups 3 to 6 received pretreatments of EECEL (50, 100, and 200 mg/kg, p. o.) and donepezil (1 mg/kg, p. o.) 30 min before scopolamine (3 mg/kg), for seven days. Following treatments, behavioral (learning and memory) assessments were carried out, while biochemical (acetylcholinesterase activity, oxidative stress markers, inflammatory cytokines markers) and histological evaluations were done after euthanasia.

RESULTS

Scopolamine significantly impaired spatial, long term and recognition memory. Nevertheless, administration of EECEL (50, 100, and 200 mg/kg orally) enhanced memory function in mice, as observed in the Y maze [F (5, 30) = 20.23, p < 0.0001], Morris water maze [F (10, 90) = 3.105, p = 0.0019; [F (5, 30) = 21.13, p < 0.0001]], and novel object recognition tasks [F (5, 30) = 37.22, p < 0.0001)]. Scopolamine-treated mice exhibited significant dysfunction in the cholinergic system, as evidenced by elevated AChE activity [0.099 ± 0.005 vs. 0.063 ± 0.004 mol/min/g] with an elevation in oxidative stress. On the other hand, administration of EECEL counteracted these consequences by reducing AChE activity, mitigating oxidative damage, reducing pro-inflammatory cytokines, and preventing degeneration of neurons.

CONCLUSION

The results demonstrated that EECEL effectively mitigates scopolamine-induced memory impairment via an oxido-inflammatory mechanism and modulation of the central cholinergic system.

Advancing the understanding of diabetic encephalopathy through unravelling pathogenesis and exploring future treatment perspectives

Diabetic encephalopathy (DE), a significant micro-complication of diabetes, manifests as neurochemical, structural, behavioral, and cognitive alterations. This condition is especially dangerous for the elderly because aging raises the risk of neurodegenerative disorders and cognitive impairment, both of which can be made worse by diabetes. Despite its severity, diagnosis of this disease is challenging, and there is a paucity of information on its pathogenesis. The pivotal roles of various cellular pathways, activated or influenced by hyperglycemia, insulin sensitivity, amyloid accumulation, tau hyperphosphorylation, brain vasculopathy, neuroinflammation, and oxidative stress, are widely recognized for contributing to the potential causes of diabetic encephalopathy. We also reviewed current pharmacological strategies for DE encompassing a comprehensive approach targeting metabolic dysregulations and neurological manifestations. Antioxidant-based therapies hold promise in mitigating oxidative stress-induced neuronal damage, while anti-diabetic drugs offer neuroprotective effects through diverse mechanisms, including modulation of insulin signaling pathways and neuroinflammation. Additionally, tissue engineering and nanomedicine-based approaches present innovative strategies for targeted drug delivery and regenerative therapies for DE. Despite significant progress, challenges remain in translating these therapeutic interventions into clinical practice, including long-term safety, scalability, and regulatory approval. Further research is warranted to optimize these approaches and address remaining gaps in the management of DE and associated neurodegenerative disorders.

α-Tocotrienol Protects Neurons by Preventing Tau Hyperphosphorylation via Inhibiting Microtubule Affinity-Regulating Kinase Activation

In the pathological process of Alzheimer's disease, neuronal cell death is closely related to the accumulation of reactive oxygen species. Our previous studies have found that oxidative stress can activate microtubule affinity-regulating kinases, resulting in elevated phosphorylation levels of tau protein specifically at the Ser262 residue in N1E-115 cells that have been subjected to exposure to hydrogen peroxide. This process may be one of the pathogenic mechanisms of Alzheimer's disease. Vitamin E is a fat-soluble, naturally occurring antioxidant that plays a crucial role in biological systems. This study aimed to examine the probable processes that contribute to the inhibiting effect on the abnormal phosphorylation of tau protein and the neuroprotective activity of a particular type of vitamin E, α-tocotrienol. The experimental analysis revealed that α-tocotrienol showed significant neuroprotective effects in the N1E-115 cell line. Our data further suggest that one of the mechanisms underlying the neuroprotective effects of α-tocotrienol may be through the inhibition of microtubule affinity-regulated kinase activation, which significantly reduces the oxidative stress-induced aberrant elevation of p-Tau (Ser262) levels. These results indicate that α-tocotrienol may represent an intriguing strategy for treating or preventing Alzheimer's disease.

A Series of Novel 1-H-isoindole-1,3(2H)-dione Derivatives as Acetylcholinesterase and Butyrylcholinesterase Inhibitors: In Silico, Synthesis and In Vitro Studies

The derivatives of isoindoline-1,3-dione are interesting due to their biological activities, such as anti-inflammatory and antibacterial effects. Several series have been designed and evaluated for Alzheimer's therapy candidates. They showed promising activity. In this work, six new derivatives were first tested in in silico studies for their inhibitory ability against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. Molecular docking and molecular dynamic simulation were applied. Next, these compounds were synthesized and characterized by 1H NMR, 13C NMR, FT-IR, and ESI-MS techniques. For all imides, the inhibitory activity against AChE and BuChE was tested using Ellaman's method. IC50 values were determined. The best results were obtained for the derivative I, with a phenyl substituent at position 4 of piperazine, IC50 = 1.12 μM (AChE) and for the derivative III, with a diphenylmethyl moiety, with IC50 = 21.24 μM (BuChE). The compounds tested in this work provide a solid basis for further structural modifications, leading to the effective design of potential inhibitors of both cholinesterases.

New 1,2,4-oxadiazole derivatives as potential multifunctional agents for the treatment of Alzheimer's disease: design, synthesis, and biological evaluation

A series of new 1,2,4-oxadiazole-based derivatives were synthesized and evaluated for their anti-AD potential. The results revealed that eleven compounds (1b, 2a-c, 3b, 4a-c, and 5a-c) exhibited excellent inhibitory potential against AChE, with IC50 values ranging from 0.00098 to 0.07920 µM. Their potency was 1.55 to 125.47 times higher than that of donepezil (IC50 = 0.12297 µM). In contrast, the newly synthesized oxadiazole derivatives with IC50 values in the range of 16.64-70.82 µM exhibited less selectivity towards BuChE when compared to rivastigmine (IC50 = 5.88 µM). Moreover, oxadiazole derivative 2c (IC50 = 463.85 µM) was more potent antioxidant than quercetin (IC50 = 491.23 µM). Compounds 3b (IC50 = 536.83 µM) and 3c (IC50 = 582.44 µM) exhibited comparable antioxidant activity to that of quercetin. Oxadiazole derivatives 3b (IC50 = 140.02 µM) and 4c (IC50 = 117.43 µM) showed prominent MAO-B inhibitory potential. They were more potent than biperiden (IC50 = 237.59 µM). Compounds 1a, 1b, 3a, 3c, and 4b exhibited remarkable MAO-A inhibitory potential, with IC50 values ranging from 47.25 to 129.7 µM. Their potency was 1.1 to 3.03 times higher than that of methylene blue (IC50 = 143.6 µM). Most of the synthesized oxadiazole derivatives provided significant protection against induced HRBCs lysis, revealing the nontoxic effect of the synthesized compounds, thus making them safe drug candidates. The results unveiled oxadiazole derivatives 2b, 2c, 3b, 4a, 4c, and 5a as multitarget anti-AD agents. The high AChE inhibitory potential can be computationally explained by the synthesized oxadiazole derivatives' significant interactions with the AChE active site. Compound 2b showed good physicochemical properties. All these data suggest that 2b could be considered as a promising candidate for future development.

An easy-to-perform method for microvessel isolation and primary brain endothelial cell culture to study Alzheimer's disease

Dysfunction of the blood-brain barrier (BBB) has been increasingly recognised as a critical early event in Alzheimer's disease (AD) pathophysiology. Central to this mechanism is the impaired function of brain endothelial cells (BECs), the primary structural constituents of the BBB, the study of which is imperative for understanding AD pathophysiology. However, the published methods to isolate BECs are time-consuming and have a low success rate. Here, we developed a rapid and streamlined protocol for BEC isolation without using transgenic reporters, flow cytometry, and magnetic beads, which are essential for existing methods. Using this novel protocol, we isolated high-purity BECs from cell clusters of cortical microvessels from wild-type and APPswe/PS1dE9 (APP/PS1, a classical AD model) mice at 2, 4 and 9 months of age. Reduced levels of tight junction proteins Claudin-5 and Zonula Occludens-1, as well as glucose transporter 1, were observed in the isolated cortical microvessels from APP/PS1 mice and amyloid-β (Aβ) oligomer-treated BECs from wild-type mice. Trans-well permeability assay showed increased FITC-dextran leakage in BECs treated with Aβ, suggesting impaired BBB permeability. BECs obtained using our novel protocol can undergo various experimental analyses, including immunofluorescence staining, western blotting, real-time PCR, and trans-well permeability assay. In conclusion, our novel protocol represents a reliable and valuable tool for in vitro modelling BBB to study AD-related mechanisms and develop targeted therapeutic strategies.

Phytoactive drugs used in the treatment of Alzheimer's disease and dementia

The prevalence of Alzheimer's disease and other forms of dementia is increasing worldwide, and finding effective treatments for these conditions is a major public health challenge. Natural bioactive drugs have been identified as a promising source of potential treatments, due to their ability to target multiple pathways and their low toxicity. This paper reviews the current state of research on natural bioactive drugs used in the treatment of Alzheimer's disease and other dementias. The paper summarizes the findings of studies on various natural compounds, including curcumin, resveratrol, caffeine, genistein, quercetin, GinkoBiloba, Withaniasomnifera, Ginseng Brahmi, Giloy, and huperzine, and their effects on cognitive function, neuroinflammation, and amyloid-beta accumulation. In this review, we discuss the mechanism of action involved in the treatment of Alzheimer's disease. The paper also discusses the challenges associated with developing natural bioactive drugs for dementia treatment, including issues related to bioavailability and standardization. Finally, the paper suggests directions for future research in this area, including the need for more rigorous clinical trials and the development of novel delivery systems to improve the efficacy of natural bioactive drugs. Overall, this review highlights the potential of natural bioactive drugs as a promising avenue for the development of safe and effective treatments for Alzheimer's disease and other dementias.

Unveiling the Complex Role of Exosomes in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative illness, characterized by memory loss and cognitive decline, accounting for 60-80% of dementia cases. AD is characterized by senile plaques made up of amyloid β (Aβ) protein, intracellular neurofibrillary tangles caused by hyperphosphorylation of tau protein linked with microtubules, and neuronal loss. Currently, therapeutic treatments and nanotechnological developments are effective in treating the symptoms of AD, but a cure for the illness has not yet been found. Recently, the increased study of extracellular vesicles (EVs) has led to a growing awareness of their significant involvement in neurodegenerative disorders, including AD. Exosomes are small extracellular vesicles that transport various components including messenger RNAs, non-coding RNAs, proteins, lipids, DNA, and other bioactive compounds from one cell to another, facilitating information transmission and material movement. There is growing evidence indicating that exosomes have complex functions in AD. Exosomes may have a dual role in Alzheimer's disease by contributing to neuronal death and also helping to alleviate the pathological progression of the disease. Therefore, the primary aim of this review is to outline the updated understandings on exosomes biogenesis and many functions of exosomes in the generation, conveyance, distribution, and elimination of hazardous proteins related to Alzheimer's disease. This review is intended to provide novel insights for understanding the development, specific treatment, and early detection of Alzheimer's disease.

Experimental verification about treatment of Bu-Shen-Yi-Jing-Fang in Alzheimer's disease by the analysis of the feasible signaling pathway of network pharmacology

CONTEXT

Bu-shen-yi-jing-fang (BSYJF) has been reported to reduce amyloid-β (Aβ)1-42 deposition in the brain of APP/PS1 mice and ameliorate cognitive function. However, its neuroprotective mechanism remains unclear.

OBJECTIVE

This study aims to investigate whether BSYJF exerts a protective effect on Aβ1-42-induced oxidative stress injury and explore its possible mechanism.

MATERIALS AND METHODS

The platform databases TCMSP, Swiss, TTD, DrugBank, and GeneCards were used to mine the targets of Alzheimer's disease (AD) and BSYJF. The platform databases STRING and Metascape were used to build the interaction network of the target protein, and Cytoscape software was used to analyze this network and screen out the key pathways. Aβ1-42-treated SKNMC cells were established to verify the mechanism of BSYJF and the key proteins. The downstream proteins and antioxidants as well as apoptosis and ferroptosis of the PI3K/AKT/Nrf2 signaling pathway were validated using an in vitro SKNMC cell model experiment. The expression levels of related proteins were detected using Western blotting. Flow cytometry and immunofluorescence staining were used to analyze apoptosis and ferroptosis.

RESULTS

Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis considered the key signal pathways, mainly involving the PI3K/AKT signaling pathway. Experimental validation demonstrated that BSYJF treatment markedly increased the activity of the PI3K/AKT pathway, which could exert anti-AD effects.

CONCLUSIONS

Our data provided compelling evidence that the protective effects of BSYJF might be associated with their regulation of the PI3K/AKT/Nrf2 signaling pathway. These studies offered a potential therapy for natural herbal medicine treatment of AD.

Naringenin: its chemistry and roles in neuroprotection

According to epidemiological research, as the population ages, neurological illnesses are becoming a bigger issue. Despite improvements in the treatment of these diseases, there are still widespread worries about how to find a long-lasting remedy. Several neurological diseases can be successfully treated with natural substances. As a result, current research has been concentrated on finding effective neuroprotective drugs with improved efficacy and fewer side effects. Naringenin is one potential treatment for neurodegenerative diseases. Many citrus fruits, tomatoes, bergamots, and other fruits are rich in naringenin, a flavonoid. This phytochemical is linked to a variety of biological functions. Naringenin has attracted a lot of interest for its ability to exhibit neuroprotection through several mechanisms. In the current article, we present evidence from the literature that naringenin reduces neurotoxicity and oxidative stress in brain tissues. Also, the literatures that are currently accessible shows that naringenin reduces neuroinflammation and other neurological anomalies. Additionally, we found several studies that touted naringenin as a promising anti-amyloidogenic, antidepressant, and neurotrophic treatment option. This review's major goal is to reflect on advancements in knowledge of the molecular processes that underlie naringenin's possible neuroprotective effects. Furthermore, this article also provides highlights of Naringenin with respect to its chemistry and pharmacokinetics.

Protein Kinase C (PKC) in Neurological Health: Implications for Alzheimer's Disease and Chronic Alcohol Consumption

Protein kinase C (PKC) is a diverse enzyme family crucial for cell signalling in various organs. Its dysregulation is linked to numerous diseases, including cancer, cardiovascular disorders, and neurological problems. In the brain, PKC plays pivotal roles in synaptic plasticity, learning, memory, and neuronal survival. Specifically, PKC's involvement in Alzheimer's Disease (AD) pathogenesis is of significant interest. The dysregulation of PKC signalling has been linked to neurological disorders, including AD. This review elucidates PKC's pivotal role in neurological health, particularly its implications in AD pathogenesis and chronic alcohol addiction. AD, characterised by neurodegeneration, implicates PKC dysregulation in synaptic dysfunction and cognitive decline. Conversely, chronic alcohol consumption elicits neural adaptations intertwined with PKC signalling, exacerbating addictive behaviours. By unravelling PKC's involvement in these afflictions, potential therapeutic avenues emerge, offering promise for ameliorating their debilitating effects. This review navigates the complex interplay between PKC, AD pathology, and alcohol addiction, illuminating pathways for future neurotherapeutic interventions.

Inhibiting the Keap1/Nrf2 Protein-Protein Interaction with Protein-Like Polymers

Successful and selective inhibition of the cytosolic protein-protein interaction (PPI) between nuclear factor erythroid 2-related factor 2 (Nrf2) and Kelch-like ECH-associating protein 1 (Keap1) can enhance the antioxidant response, with the potential for a therapeutic effect in a range of settings including in neurodegenerative disease (ND). Small molecule inhibitors have been developed, yet many have off-target effects, or are otherwise limited by poor cellular permeability. Peptide-based strategies have also been attempted to enhance specificity, yet face challenges due to susceptibility to degradation and lack of cellular penetration. Herein, these barriers are overcome utilizing a polymer-based proteomimetics. The protein-like polymer (PLP) consists of a synthetic, lipophilic polymer backbone displaying water soluble Keap1-binding peptides on each monomer unit forming a brush polymer architecture. The PLPs are capable of engaging Keap1 and displacing the cellular protective transcription factor Nrf2, which then translocates to the nucleus, activating the antioxidant response element (ARE). PLPs exhibit increased Keap1 binding affinity by several orders of magnitude compared to free peptides, maintain serum stability, are cell-penetrant, and selectively activate the ARE pathway in cells, including in primary cortical neuronal cultures. Keap1/Nrf2-inhibitory PLPs have the potential to impact the treatment of disease states associated with dysregulation of oxidative stress, such as NDs.

Label-Free In Situ Chemical Characterization of Amyloid Plaques in Human Brain Tissues

The accumulation of amyloid plaques and increased brain redox burdens are neuropathological hallmarks of Alzheimer's disease. Altered metabolism of essential biometals is another feature of Alzheimer's, with amyloid plaques representing sites of disturbed metal homeostasis. Despite these observations, metal-targeting disease treatments have not been therapeutically effective to date. A better understanding of amyloid plaque composition and the role of the metals associated with them is critical. To establish this knowledge, the ability to resolve chemical variations at nanometer length scales relevant to biology is essential. Here, we present a methodology for the label-free, nanoscale chemical characterization of amyloid plaques within human Alzheimer's disease tissue using synchrotron X-ray spectromicroscopy. Our approach exploits a C-H carbon absorption feature, consistent with the presence of lipids, to visualize amyloid plaques selectively against the tissue background, allowing chemical analysis to be performed without the addition of amyloid dyes that alter the native sample chemistry. Using this approach, we show that amyloid plaques contain elevated levels of calcium, carbonates, and iron compared to the surrounding brain tissue. Chemical analysis of iron within plaques revealed the presence of chemically reduced, low-oxidation-state phases, including ferromagnetic metallic iron. The zero-oxidation state of ferromagnetic iron determines its high chemical reactivity and so may contribute to the redox burden in the Alzheimer's brain and thus drive neurodegeneration. Ferromagnetic metallic iron has no established physiological function in the brain and may represent a target for therapies designed to lower redox burdens in Alzheimer's disease. Additionally, ferromagnetic metallic iron has magnetic properties that are distinct from the iron oxide forms predominant in tissue, which might be exploitable for the in vivo detection of amyloid pathologies using magnetically sensitive imaging. We anticipate that this label-free X-ray imaging approach will provide further insights into the chemical composition of amyloid plaques, facilitating better understanding of how plaques influence the course of Alzheimer's disease.

Ligustilide-loaded liposome ameliorates mitochondrial impairments and improves cognitive function via the PKA/AKAP1 signaling pathway in a mouse model of Alzheimer's disease

BACKGROUND

Oxidative stress is an early event in the development of Alzheimer's disease (AD) and maybe a pivotal point of interaction governing AD pathogenesis; oxidative stress contributes to metabolism imbalance, protein misfolding, neuroinflammation and apoptosis. Excess reactive oxygen species (ROS) are a major contributor to oxidative stress. As vital sources of ROS, mitochondria are also the primary targets of ROS attack. Seeking effective avenues to reduce oxidative stress has attracted increasing attention for AD intervention.

METHODS

We developed liposome-packaged Ligustilide (LIG) and investigated its effects on mitochondrial function and AD-like pathology in the APPswe/PS1dE9 (APP/PS1) mouse model of AD, and analyzed possible mechanisms.

RESULTS

We observed that LIG-loaded liposome (LIG-LPs) treatment reduced oxidative stress and β-amyloid (Aβ) deposition and mitigated cognitive impairment in APP/PS1 mice. LIG management alleviated the destruction of the inner structure in the hippocampal mitochondria and ameliorated the imbalance between mitochondrial fission and fusion in the APP/PS1 mouse brain. We showed that the decline in cAMP-dependent protein kinase A (PKA) and A-kinase anchor protein 1 for PKA (AKAP1) was associated with oxidative stress and AD-like pathology. We confirmed that LIG-mediated antioxidant properties and neuroprotection were involved in upregulating the PKA/AKAP1 signaling in APPswe cells in vitro.

CONCLUSION

Liposome packaging for LIG is relatively biosafe and can overcome the instability of LIG. LIG alleviates mitochondrial dysfunctions and cognitive impairment via the PKA/AKAP1 signaling pathway. Our results provide experimental evidence that LIG-LPs may be a promising agent for AD therapy.

Antioxidant Efficacy of Hwangryunhaedok-tang through Nrf2 and AMPK Signaling Pathway against Neurological Disorders In Vivo and In Vitro

Alzheimer's disease (AD) is a representative cause of dementia and is caused by neuronal loss, leading to the accumulation of aberrant neuritic plaques and the formation of neurofibrillary tangles. Oxidative stress is involved in the impaired clearance of amyloid beta (Aβ), and Aβ-induced oxidative stress causes AD by inducing the formation of neurofibrillary tangles. Hwangryunhaedok-tang (HHT, Kracie K-09®), a traditional herbal medicine prescription, has shown therapeutic effects on various diseases. However, the studies of HHT as a potential treatment for AD are insufficient. Therefore, our study identified the neurological effects and mechanisms of HHT and its key bioactive compounds against Alzheimer's disease in vivo and in vitro. In a 5xFAD mouse model, our study confirmed that HHT attenuated cognitive impairments in the Morris water maze (MWM) test and passive avoidance (PA) test. In addition, the prevention of neuron impairment, reduction in the protein levels of Aβ, and inhibition of cell apoptosis were confirmed with brain tissue staining. In HT-22 cells, HHT attenuates tBHP-induced cytotoxicity, ROS generation, and mitochondrial dysfunction. It was verified that HHT exerts a neuroprotective effect by activating signaling pathways interacting with Nrf2, such as MAPK/ERK, PI3K/Akt, and LKB1/AMPK. Among the components, baicalein, a bioavailable compound of HHT, exhibited neuroprotective properties and activated the Akt, AMPK, and Nrf2/HO-1 pathways. Our findings indicate a mechanism for HHT and its major bioavailable compounds to treat and prevent AD and suggest its potential.

Discovery of Quinolinone Hybrids as Dual Inhibitors of Acetylcholinesterase and Aβ Aggregation for Alzheimer's Disease Therapy

The development of multitargeted therapeutics has evolved as a promising strategy to identify efficient therapeutics for neurological disorders. We report herein new quinolinone hybrids as dual inhibitors of acetylcholinesterase (AChE) and Aβ aggregation that function as multitargeted ligands for Alzheimer's disease. The quinoline hybrids (AM1-AM16) were screened for their ability to inhibit AChE, BACE1, amyloid fibrillation, α-syn aggregation, and tau aggregation. Among the tested compounds, AM5 and AM10 inhibited AChE activity by more than 80% at single-dose screening and possessed a remarkable ability to inhibit the fibrillation of Aβ42 oligomers at 10 μM. In addition, dose-dependent screening of AM5 and AM10 was performed, giving half-maximal AChE inhibitory concentration (IC50) values of 1.29 ± 0.13 and 1.72 ± 0.18 μM, respectively. In addition, AM5 and AM10 demonstrated concentration-dependent inhibitory profiles for the aggregation of Aβ42 oligomers with estimated IC50 values of 4.93 ± 0.8 and 1.42 ± 0.3 μM, respectively. Moreover, the neuroprotective properties of the lead compounds AM5 and AM10 were determined in SH-SY5Y cells incubated with Aβ oligomers. This work would enable future research efforts aiming at the structural optimization of AM5 and AM10 to develop potent dual inhibitors of AChE and amyloid aggregation. Furthermore, the in vivo assay confirmed the antioxidant activity of compounds AM5 and AM10 through increasing GSH, CAT, and SOD activities that are responsible for scavenging the ROS and restoring its normal level. Blood investigation illustrated the protective activity of the two compounds against lead-induced neurotoxicity through retaining hematological and liver enzymes near normal levels. Finally, immunohistochemistry investigation revealed the inhibitory activity of β-amyloid (Aβ) aggregation.

Missing Puzzle Pieces in Dementia Research: HCN Channels and Theta Oscillations

Increasing evidence indicates a role of hyperpolarization activated cation (HCN) channels in controlling the resting membrane potential, pacemaker activity, memory formation, sleep, and arousal. Their disfunction may be associated with the development of epilepsy and age-related memory decline. Neuronal hyperexcitability involved in epileptogenesis and EEG desynchronization occur in the course of dementia in human Alzheimer's Disease (AD) and animal models, nevertheless the underlying ionic and cellular mechanisms of these effects are not well understood. Some suggest that theta rhythms involved in memory formation could be used as a marker of memory disturbances in the course of neurogenerative diseases, including AD. This review focusses on the interplay between hyperpolarization HCN channels, theta oscillations, memory formation and their role(s) in dementias, including AD. While individually, each of these factors have been linked to each other with strong supportive evidence, we hope here to expand this linkage to a more inclusive picture. Thus, HCN channels could provide a molecular target for developing new therapeutic agents for preventing and/or treating dementia.

Investigating the combined effect of copper, zinc, and iron ions on truncated and full-length Aβ peptides: insights from molecular dynamics simulation

The truncated Aβ1 - 16 peptide containing the metal-binding domain is frequently used in in silico and experimental investigations because it is more soluble and thus more suitable for studies in solution and does not form amyloids. Several spectroscopic studies have shown that the metal binding of Aβ1 - 16 is very similar to that of the full-length Aβ1 - 42. However, since small changes can have a significant impact on aggregation, further experimental and theoretical are needed to elucidate the detailed structures of truncated and full-length Aβ. In this research, the binding of copper ion to the Aβ1 - 16 and Aβ1 - 42 has been studied by molecular dynamics simulation method. To investigate the effect of copper ion on beta-amyloid peptide structure, the simulations were repeated in the copper and zinc ions, copper and iron binary system, and the copper, zinc and iron ions ternary system. The conformation factor was calculated to calculate the binding affinity of copper ion to beta-amyloid peptide residues. The results showed that the initial 16 residues of the beta-amyloid peptide have high binding affinity for copper ions, and histidine 13 and histidine 14 have significantly higher binding affinity for copper ions in all studied systems. Zinc and iron ions were found to reduce the conformational factor of peptide residues in binding to copper ions, and the aggregation tendency was lower in the truncated structure. The SASA results suggest that the side chains of peptide residues are more affected by shortening and the presence of ions.Communicated by Ramaswamy H. Sarma.

Multitarget Protective Effects of JUB on Aβ-Induced Neurotoxicity and the Mechanism Predication Using Network Pharmacology Analysis

Amyloid-β (Aβ) is one of the core factors in the pathogenesis of Alzheimer's disease (AD), and the accumulation of its aggregates in the brain can form age-related plaques, leading to brain cell damage and intellectual decline, which may be the common intersection of all causes of neurotoxicity. Jujuboside B (JUB) has many characteristics such as hypnosis, sedation, antianxiety, and antioxidant stress. However, it is still unclear whether JuB can alleviate the neurotoxicity caused by Aβ. Our study demonstrates that JUB improves learning and memory deficits in the nematode model. At the same time, JUB increases the antioxidant activity, prevents excessive accumulation of lipid synthesis, and resists endogenous lipofuscin deposition, thereby inhibiting the toxic effect of Aβ. In vitro, JUB can improve Aβ1-42-induced neuronal apoptosis level through the Bax/Bcl-2/caspase-3 signaling pathway and restore mitochondrial function in SH-SY5Y cells. The network pharmacology has been used to predict the potential neuroprotective mechanism of JUB. In summary, JUB exhibits neuroprotective properties employing both a neural cell and a nematode, which provides a basis for screening candidate ingredients for preventing AD.

Polyherbal and Multimodal Treatments: Kaempferol- and Quercetin-Rich Herbs Alleviate Symptoms of Alzheimer's Disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder impairing cognition and memory in the elderly. This disorder has a complex etiology, including senile plaque and neurofibrillary tangle formation, neuroinflammation, oxidative stress, and damaged neuroplasticity. Current treatment options are limited, so alternative treatments such as herbal medicine could suppress symptoms while slowing cognitive decline. We followed PRISMA guidelines to identify potential herbal treatments, their associated medicinal phytochemicals, and the potential mechanisms of these treatments. Common herbs, including Ginkgo biloba, Camellia sinensis, Glycyrrhiza uralensis, Cyperus rotundus, and Buplerum falcatum, produced promising pre-clinical results. These herbs are rich in kaempferol and quercetin, flavonoids with a polyphenolic structure that facilitate multiple mechanisms of action. These mechanisms include the inhibition of Aβ plaque formation, a reduction in tau hyperphosphorylation, the suppression of oxidative stress, and the modulation of BDNF and PI3K/AKT pathways. Using pre-clinical findings from quercetin research and the comparatively limited data on kaempferol, we proposed that kaempferol ameliorates the neuroinflammatory state, maintains proper cellular function, and restores pro-neuroplastic signaling. In this review, we discuss the anti-AD mechanisms of quercetin and kaempferol and their limitations, and we suggest a potential alternative treatment for AD. Our findings lead us to conclude that a polyherbal kaempferol- and quercetin-rich cocktail could treat AD-related brain damage.

Effects of amyloid β (Aβ)42 and Gasdermin D on the progression of Alzheimer's disease in vitro and in vivo through the regulation of astrocyte pyroptosis

PURPOSE

The study aimed to investigate whether astrocyte pyroptosis, and the subsequent neuroinflammatory response that exerts amyloid β (Aβ) neurotoxic effects, has an effect on endothelial cells, along with the underlying mechanisms.

METHODS

In vivo, 5 μL of disease venom was injected into the lateral ventricle of APP/PS1 mice for treatment. Pyroptosis was induced by treating astrocytes with Aβ42 in vitro. Small interfering RNA (siRNA) was used to silence caspase-1 and Gasdermin D (GSDMD) mRNA expression. Cell viability was determined using a CCK-8 detection kit. Scanning electron microscopy (SEM), Annexin V/propidium iodide (PI) double staining, RT-qPCR, immunofluorescence, western blotting, and enzyme-linked immunosorbent assay (ELISA) were used to detect cell pyroptosis. The degree of pathological damage to the brain and aortic tissue was assessed by hematoxylin-eosin staining and immunohistochemistry.

RESULTS

Aβ42 induced astrocyte pyroptosis dependent on the GSDMD/Gasdermin E (GSDME)/Caspase 11/NLRP3 pathway, releasing large amounts of inflammatory factors, such as TNF-α, IL-1α, IL-1β, and IL-18. Astrocyte pyroptosis caused endothelial cell dysfunction and release of large amounts of vasoconstrictors (ET and vWF). Knockdown of GSDMD reduced astrocyte pyroptosis in the cerebral cortex and hippocampal tissue, decreased the release of inflammatory factors IL-1 β and IL-18, reduced Aβ deposition and tau protein, increased the release of peripheral vasodilator substances (eNOS), and decreased the release of vasoconstrictor substances (ET, vWF), thereby reducing brain tissue damage and vascular injury in APP/PS1 mice.

CONCLUSION

Aβ42 induced astrocyte pyroptosis, while GSDMD knockout inhibited astrocyte pyroptosis, reduced the release of inflammatory factors, and alleviated brain tissue damage and vascular damage in APP/PS1 mice. Therefore, GSDMD is a novel therapeutic target for Alzheimer's disease.

PURPOSE

The study aimed to investigate whether astrocyte pyroptosis, and the subsequent neuroinflammatory response that exerts amyloid β (Aβ) neurotoxic effects, has an effect on endothelial cells, along with the underlying mechanisms.

METHODS

In vivo, 5 μL of disease venom was injected into the lateral ventricle of APP/PS1 mice for treatment. Pyroptosis was induced by treating astrocytes with Aβ42 in vitro. Small interfering RNA (siRNA) was used to silence caspase-1 and Gasdermin D (GSDMD) mRNA expression. Cell viability was determined using a CCK-8 detection kit. Scanning electron microscopy (SEM), Annexin V/propidium iodide (PI) double staining, RT-qPCR, immunofluorescence, western blotting, and enzyme-linked immunosorbent assay (ELISA) were used to detect cell pyroptosis. The degree of pathological damage to the brain and aortic tissue was assessed by hematoxylin-eosin staining and immunohistochemistry.

RESULTS

Aβ42 induced astrocyte pyroptosis dependent on the GSDMD/Gasdermin E (GSDME)/Caspase 11/NLRP3 pathway, releasing large amounts of inflammatory factors, such as TNF-α, IL-1α, IL-1β, and IL-18. Astrocyte pyroptosis caused endothelial cell dysfunction and release of large amounts of vasoconstrictors (ET and vWF). Knockdown of GSDMD reduced astrocyte pyroptosis in the cerebral cortex and hippocampal tissue, decreased the release of inflammatory factors IL-1 β and IL-18, reduced Aβ deposition and tau protein, increased the release of peripheral vasodilator substances (eNOS), and decreased the release of vasoconstrictor substances (ET, vWF), thereby reducing brain tissue damage and vascular injury in APP/PS1 mice.

CONCLUSION

Aβ42 induced astrocyte pyroptosis, while GSDMD knockout inhibited astrocyte pyroptosis, reduced the release of inflammatory factors, and alleviated brain tissue damage and vascular damage in APP/PS1 mice. Therefore, GSDMD is a novel therapeutic target for Alzheimer's disease.

Effects of Walnut and Pumpkin on Selective Neurophenotypes of Autism Spectrum Disorders: A Case Study

Special diets or nutritional supplements are regularly given to treat children with autism spectrum disorder (ASD). The increased consumption of particular foods has been demonstrated in numerous trials to lessen autism-related symptoms and comorbidities. A case study on a boy with moderate autism who significantly improved after three years of following a healthy diet consisting of pumpkin and walnuts was examined in this review in connection to a few different neurophenotypes of ASD. We are able to suggest that a diet high in pumpkin and walnuts was useful in improving the clinical presentation of the ASD case evaluated by reducing oxidative stress, neuroinflammation, glutamate excitotoxicity, mitochondrial dysfunction, and altered gut microbiota, all of which are etiological variables. Using illustrated figures, a full description of the ways by which a diet high in pumpkin and nuts could assist the included case is offered.

Cholinergic neurodegeneration and cholesterol metabolism dysregulation by constitutive p75NTR signaling in the p75exonIII-KO mice

Degeneration of basal forebrain cholinergic neurons (BFCNs) is a hallmark of Alzheimer's disease (AD). However, few mouse models of AD recapitulate the neurodegeneration of the cholinergic system. The p75 neurotrophin receptor, p75NTR, has been associated with the degeneration of BFCNs in AD. The senescence-accelerated mouse prone number 8 (SAMP8) is a well-accepted model of accelerated and pathological aging. To gain a better understanding of the role of p75NTR in the basal forebrain during aging, we generated a new mouse line, the SAMP8-p75exonIII-/-. Deletion of p75NTR in the SAMP8 background induces an increase in the number of BFCNs at birth, followed by a rapid decline during aging compared to the C57/BL6 background. This decrease in the number of BFCNs correlates with a worsening in the Y-maze memory test at 6 months in the SAMP8-p75exonIII-/-. We found that SAMP8-p75exonIII-/- and C57/BL6-p75exonIII-/- mice expressed constitutively a short isoform of p75NTR that correlates with an upregulation of the protein levels of SREBP2 and its targets, HMGCR and LDLR, in the BF of both SAMP8-p75exonIII-/- and C57/BL6-p75exonIII-/- mice. As the neurodegeneration of the cholinergic system and the dysregulation of cholesterol metabolism are implicated in AD, we postulate that the generated SAMP8-p75exonIII-/- mouse strain might constitute a good model to study long-term cholinergic neurodegeneration in the CNS. In addition, our results support the role of p75NTR signaling in cholesterol biosynthesis regulation.

Quinoline Derivatives: Promising Antioxidants with Neuroprotective Potential

Quinoline has been proposed as a privileged molecular framework in medicinal chemistry. Although by itself it has very few applications, its derivatives have diverse biological activities. In this work, 8536 quinoline derivatives, strategically designed using the CADMA-Chem protocol, are presented. This large chemical space was sampled, analyzed and reduced using selection and elimination scores that combine their properties of bioavailability, toxicity and manufacturability. After applying several filters, 25 derivatives were selected to investigate their acid-base, antioxidant and neuroprotective properties. The antioxidant activity was predicted based on the ionization potential and bond dissociation energies, parameters directly related to the transfer of hydrogen atoms and of a single electron, respectively. These two mechanisms are typically involved in the radical scavenging processes. The antioxidant efficiency was compared with reference compounds, and the most promising antioxidants were found to be more efficient than Trolox but less efficient than ascorbate. In addition, based on molecular docking simulations, some derivatives are expected to act as inhibitors of catechol-O methyltransferase (COMT), acetylcholinesterase (AChE) and monoamine oxidase type B (MAO-B) enzymes. Some structural insights about the compounds were found to enhance or decrease the neuroprotection activity. Based on the results, four quinoline derivatives are proposed as candidates to act as multifunctional antioxidants against Alzheimer's (AD) and Parkinson's (PD) diseases.

The association of long-term exposure to criteria air pollutants, fine particulate matter components, and airborne trace metals with late-life brain amyloid burden in the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

Studies suggest associations between long-term ambient air pollution exposure and outcomes related to Alzheimer's disease (AD). Whether a link exists between pollutants and brain amyloid accumulation, a biomarker of AD, is unclear. We assessed whether long-term air pollutant exposures are associated with late-life brain amyloid deposition in Atherosclerosis Risk in Communities (ARIC) study participants.

METHODS

We used a chemical transport model with data fusion to estimate ambient concentrations of PM2.5 and its components, NO2, NOx, O3 (24-hour and 8-hour), CO, and airborne trace metals. We linked concentrations to geocoded participant addresses and calculated 10-year mean exposures (2002 to 2011). Brain amyloid deposition was measured using florbetapir amyloid positron emission tomography (PET) scans in 346 participants without dementia in 2012-2014, and we defined amyloid positivity as a global cortical standardized uptake value ratio ≥ the sample median of 1.2. We used logistic regression models to quantify the association between amyloid positivity and each air pollutant, adjusting for putative confounders. In sensitivity analyses, we considered whether use of alternate air pollution estimation approaches impacted findings for PM2.5, NO2, NOx, and 24-hour O3.

RESULTS

At PET imaging, eligible participants (N = 318) had a mean age of 78 years, 56% were female, 43% were Black, and 27% had mild cognitive impairment. We did not find evidence of associations between long-term exposure to any pollutant and brain amyloid positivity in adjusted models. Findings were materially unchanged in sensitivity analyses using alternate air pollution estimation approaches for PM2.5, NO2, NOx, and 24-hour O3.

CONCLUSIONS

Air pollution may impact cognition and dementia independent of amyloid accumulation, though whether air pollution influences AD pathogenesis later in the disease course or at higher exposure levels deserves further consideration.

Potential therapeutic effects of naringin loaded PLGA nanoparticles for the management of Alzheimer's disease: In vitro, ex vivo and in vivo investigation

Background

Alzheimer's disease (AD) is the most prevalent type of dementia which has been affected to more the 44 million people globally. It is distinguished by gradually deteriorating memory and other cognitive abilities that precede dementia. Present treatment of AD mainly focuses on symptomatic slowing the evolution of the disease which is associated with numerous side effects such as dizziness, tiredness, nausea, vomiting, heart attack, and stroke etc. Henceforth; there is urgent need to identify the alternative treatment for management of AD. Herbal medicines have been used from long time to treat AD. One of such leading Phyto molecule is Naringin. It showed promising results against AD but suffers from poor bioavailability and require in high dose to cross the blood brain barrier.

Objectives

The main objectives of proposed work are to increase the bioavailability of naringin in brain by developing Nano-suspension and preclinical evaluation of neuroprotective effect of Naringin Nano-suspension (NNS) against Scopolamine induced Alzheimer's disease in rats.

Methods

The present study deals with the development, characterization of NNSand to evaluate neuroprotective effect of NNS. Nanoparticles of drug were formed by using PLGA polymer and optimized by using 32 factorial design. Optimized batch was further characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Further the effectiveness of NNS was preclinically investigated by performing AOTstudy as per OECD guideline 420. AD induced Albino Wistar Rats were treated with NNS orally for 14 days and then evaluated for parameters like Gross examination of brain, Relative brain weight determination, behavioural parameters, neuro-inflammatory parameters and immune-histology.

Results

Optimization was carried out to study the effect of polymer concentration and number of HPH cycles on Particle size, Poly dispersity index (PDI) and % entrapment efficiency. Desirability search approach was used to select the optimized formulation. Based on the selection criteria, batch F6 having 357.6 ± 05 nm particle size, 0.168 ± 0.04 PDI and 91 ± 2% EE was selected as optimized batch. SEM analysis showed spherical morphology and XRD confirmed the molecular dispersion. Pre-treatment with NNS showed neuroprotective activity basedon results of behavioural studies, biochemical estimation, neuroinflammatory parameters and immunohistochemistry evaluations.

Conclusion

As NNS showed significant neuroprotective and anti-neuro-inflammatory effect, this study opens up new ways to exploit Naringin for various therapeutic and restorative purposes.

Mesenchymal Stem Cells and Begacestat Mitigate Amyloid-β 25-35-Induced Cognitive Decline in Rat Dams and Hippocampal Deteriorations in Offspring

Alzheimer's disease (AD) is the most common cause of age-related neurodegeneration and cognitive decline. AD more commonly occurs in females than in males, so it is necessary to consider new treatments specifically targeting this population. The present study investigated the protective effects of Begacestat (γ-secretase inhibitor-953, GSI-953) and bone marrow-derived mesenchymal stem cells (BM-MSCs) during pregnancy on cognitive impairment in rat dams and neurodegeneration in offspring caused by the intracerebroventricular injection of Aβ 25-35 before pregnancy. The performances of dams injected with amyloid-β 25-35 (Aβ 25-35) during behavioral tests were significantly impaired. The offspring of Aβ 25-35-injected dams treated with BM-MSCs or GSI-953 showed a dramatically reduced number and size of activated microglial cells, enhancement in the processes length, and a decrease in the proinflammatory cytokine levels. Additionally, BM-MSC or GSI-953 therapy reduced Aβ 25-35-induced increases in tau phosphorylation and amyloid precursor protein levels in the neonates' hippocampus and elevated the lower levels of glycogen synthase kinase-3 and brain-derived neurotrophic factor; moreover, reversed Aβ 25-35-induced alterations in gene expression in the neonatal hippocampus. Finally, the treatments with BM-MSC or GSI-953 are globally beneficial against Aβ 25-35-induced brain alterations, particularly by suppressing neural inflammation, inhibiting microglial cell activation, restoring developmental plasticity, and increasing neurotrophic signaling.

Bone Marrow-Derived Mesenchymal Stem Cells and γ-Secretase Inhibitor Treatments Suppress Amyloid-β25-35-Induced Cognitive Impairment in Rat Dams and Cortical Degeneration in Offspring

Alzheimer's disease (AD) is the most frequent cause of age-related neurodegeneration and ensuing cognitive impairment. Progressive deposition of extracellular amyloid beta (Aβ) aggregates (plaques) and intracellular hyperphosphorylated Tau protein (p-Tau) are the core pathological markers of AD but may precede clinical symptoms by many years, presenting a therapeutic window of opportunity. Females are more frequently afflicted by AD than males, necessitating evaluation of novel treatments for the female population. The current study examined the protective efficacies of intravenous bone marrow-derived mesenchymal stem cells (BM-MSCs) and oral gamma-secretase inhibitor-953 (GSI-953) during pregnancy on cognitive impairment in rat dams and neurodegeneration in offspring induced by intracerebroventricular injection of Aβ25-35 prior to pregnancy. The Aβ25-35 (AD) group exhibited significant (P < 0.001) impairments in the Y-maze and novel object recognition test performance prior to conception. Histological analysis of the offspring cortex revealed substantial dendritic shrinkage and activation of microglial cells, while neurochemical analysis demonstrated significant increases in the proinflammatory cytokine interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). In contrast, BM-MSC or GSI-953 treatment of dams following Aβ25-35 injection significantly (P < 0.001) reduced the number and size of activated microglial cells, markedly increased dendrite length, and reversed proinflammatory cytokine elevations in offspring. Moreover, BM-MSC or GSI-953 treatment reversed the Aβ25-35-induced amyloid precursor protein and p-Tau elevations in the offspring brain; these changes were accompanied by upregulation of the brain-derived neurotrophic factor and downregulation of glycogen synthase kinase-3β in the serum and brain. Treatment with BM-MSCs or GSI-953 also reversed Aβ25-35-induced elevations in different gene expressions in the neonatal cortex. Finally, treatment of dams with BM-MSCs or GSI-953 prevented the Aβ25-35-induced disruption of newborn brain development. Thus, BM-MSC and GSI-953 treatments have broad-spectrum effects against Aβ25-35-induced brain pathology, including the suppression of neural inflammation, restoration of developmental plasticity, and promotion of neurotrophic signaling.

A Multilevel Study of Eupatorin and Scutellarein as Anti-Amyloid Agents in Alzheimer's Disease

Today, Alzheimer's disease (AD)-the most common neurodegenerative disorder, which affects 50 million people-remains incurable. Several studies suggest that one of the main pathological hallmarks of AD is the accumulation of abnormal amyloid beta (Aβ) aggregates; therefore, many therapeutic approaches focus on anti-Aβ aggregation inhibitors. Taking into consideration that plant-derived secondary metabolites seem to have neuroprotective effects, we attempted to assess the effects of two flavones-eupatorin and scutellarein-on the amyloidogenesis of Aβ peptides. Biophysical experimental methods were employed to inspect the aggregation process of Aβ after its incubation with each natural product, while we monitored their interactions with the oligomerized Aβ through molecular dynamics simulations. More importantly, we validated our in vitro and in silico results in a multicellular organismal model-namely, Caenorhabditis elegans-and we concluded that eupatorin is indeed able to delay the amyloidogenesis of Aβ peptides in a concentration-dependent manner. Finally, we propose that further investigation could lead to the exploitation of eupatorin or its analogues as potential drug candidates.

Apoptosis in Alzheimer's disease: insight into the signaling pathways and therapeutic avenues

Alzheimer's disease (AD) is characterized by the accumulation of hyperphosphorylated tau and amyloid-β (Aβ) protein resulting in synaptic loss and apoptosis. Aβ and tau deposition trigger apoptotic pathways that result in neuronal death. Apoptosis is considered to be responsible for manifestations associated with AD under pathological conditions. It regulates via extrinsic and intrinsic pathways. It activates various proteins including Bcl-2 family proteins like Bax, Bad, Bid, Bcl-XS, Bcl-XL and caspases comprising of initiator, effector and inflammatory caspases carried out through a cascade of events that finally lead to cell disintegration. The apoptotic elements interact with trophic factors, signaling molecules including Ras-ERK, JNK, GSK-3β, BDNF/TrkB/CREB and PI3K/AKT/mTOR. Ras-ERK signaling is involved in the progression of cell cycle and apoptosis. JNK pathway is also upregulated in AD which results in decreased expression of anti-apoptotic proteins. JAK-STAT triggers caspase-3 mediated apoptosis leading to neurodegeneration. The imbalance between autophagy and apoptosis is regulated by PI3K/Akt/mTOR pathway. GSK-3β is involved in the stimulation of pro-apoptotic factors resulting in dysregulation of apoptosis. Drugs like filgrastim, epigallocatechin gallate, curcumin, nicergoline and minocycline are under development which target these pathways and modulate the disease condition. This study sheds light on apoptotic pathways that are cardinal for neuronal survival and perform crucial role in the occurrence of AD along with the trends in therapeutics targeting apoptosis induced AD. To develop prospective treatments for AD, it is desirable to elucidate potential targets including restoration apoptotic balance, regulation of caspases, Bcl-2 and other crucial proteins involved in apoptosis mediated AD.

Recent Development in the Understanding of Molecular and Cellular Mechanisms Underlying the Etiopathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to dementia and patient death. AD is characterized by intracellular neurofibrillary tangles, extracellular amyloid beta (Aβ) plaque deposition, and neurodegeneration. Diverse alterations have been associated with AD progression, including genetic mutations, neuroinflammation, blood-brain barrier (BBB) impairment, mitochondrial dysfunction, oxidative stress, and metal ion imbalance.Additionally, recent studies have shown an association between altered heme metabolism and AD. Unfortunately, decades of research and drug development have not produced any effective treatments for AD. Therefore, understanding the cellular and molecular mechanisms underlying AD pathology and identifying potential therapeutic targets are crucial for AD drug development. This review discusses the most common alterations associated with AD and promising therapeutic targets for AD drug discovery. Furthermore, it highlights the role of heme in AD development and summarizes mathematical models of AD, including a stochastic mathematical model of AD and mathematical models of the effect of Aβ on AD. We also summarize the potential treatment strategies that these models can offer in clinical trials.

A novel regulator in Alzheimer's disease progression: The astrocyte-derived extracellular vesicles

Alzheimer's disease (AD) is known as an age-related irreversible neurodegenerative disease. AD seriously endangers the health of the elderly, but there is still no effective treatment. In the past several decades, the significant role of astrocytes in the process of AD has been universally acknowledged. In addition, extracellular vesicles (EVs) have been recognized as an essential mediator in intercellular communication and participate in various pathophysiological processes by carrying and transporting diverse cargoes. Moreover, specific conditions and stimuli can modulate the amount and properties of astrocyte-derived EVs (ADEVs) to affect AD progression. Thus, recent studies focused on the involvement of ADEVs in the pathogenesis of AD and the potential application of ADEVs in the diagnosis and treatment of AD, which provides a new direction and possibility for revealing the mystery of AD. Interestingly, it can be concluded that ADEVs have both pathogenic and protective effects in the process of AD through a comprehensive generalization. In this review, we aim to summarize the multi-faces of ADEVs effects on AD development, which can provide a novel strategy to investigate the underlying mechanism in AD. We also summarize the current ADEVs clinically relevant studies to raise the potential use of ADEVs in the discovery of novel biomarkers for diagnosis and therapeutic targets for AD.

A novel rhein-huprine hybrid ameliorates disease-modifying properties in preclinical mice model of Alzheimer's disease exacerbated with high fat diet

BACKGROUND

Alzheimer's disease (AD) is characterized by a polyetiological origin. Despite the global burden of AD and the advances made in AD drug research and development, the cure of the disease remains elusive, since any developed drug has demonstrated effectiveness to cure AD. Strikingly, an increasing number of studies indicate a linkage between AD and type 2 diabetes mellitus (T2DM), as both diseases share some common pathophysiological features. In fact, β-secretase (BACE1) and acetylcholinesterase (AChE), two enzymes involved in both conditions, have been considered promising targets for both pathologies. In this regard, due to the multifactorial origin of these diseases, current research efforts are focusing on the development of multi-target drugs as a very promising option to derive effective treatments for both conditions. In the present study, we evaluated the effect of rhein-huprine hybrid (RHE-HUP), a synthesized BACE1 and AChE inhibitor, both considered key factors not only in AD but also in metabolic pathologies. Thus, the aim of this study is to evaluate the effects of this compound in APP/PS1 female mice, a well-established familial AD mouse model, challenged by high-fat diet (HFD) consumption to concomitantly simulate a T2DM-like condition.

RESULTS

Intraperitoneal treatment with RHE-HUP in APP/PS1 mice for 4 weeks reduced the main hallmarks of AD, including Tau hyperphosphorylation, Aβ₄₂ peptide levels and plaque formation. Moreover, we found a decreased inflammatory response together with an increase in different synaptic proteins, such as drebrin 1 (DBN1) or synaptophysin, and in neurotrophic factors, especially in BDNF levels, correlated with a recovery in the number of dendritic spines, which resulted in memory improvement. Notably, the improvement observed in this model can be attributed directly to a protein regulation at central level, since no peripheral modification of those alterations induced by HFD consumption was observed.

CONCLUSIONS

Our results suggest that RHE-HUP could be a new candidate for the treatment of AD, even for individuals with high risk due to peripheral metabolic disturbances, given its multi-target profile which allows for the improvement of some of the most important hallmarks of the disease.

A Mixture of Artemisia argyi and Saururus chinensis Improves PM2.5-Induced Cognitive Dysfunction by Regulating Oxidative Stress and Inflammatory Response in the Lung and Brain

This study was performed to investigate the improving effect of a mixture of Artemisia argyi and Saururus chinensis (AASC) on cognitive dysfunction in mice with long-term exposure to fine particles (particulate matter smaller than 2.5 µm: PM_2.5). The main compounds of AASC were identified as dicaffeoylquinic acid isomers of A. argyi and a quercetin-3-glucoside of S. chinesis. As a result of behavioral tests for the evaluation of cognitive function, it was confirmed that cognitive dysfunction was induced in the PM_2.5 exposure group, and a tendency to improve in the AASC group was confirmed. Increased oxidative stress and inflammatory response and mitochondrial dysfunction were observed in the brain and lung tissues of the PM group. Damage to the brain and lung affected the accumulation of amyloid beta (Aβ) in the brain. It increased Aβ and induced the cholinergic dysfunction, hyperphosphorylation of the tau protein, and activation of apoptosis, leading to cognitive impairment. However, AASC suppressed brain and lung oxidative stress and inflammation, thereby suppressing brain Aβ expression. Consequently, this study shows the potential that a steady intake of plant resources with antioxidant and anti-inflammatory activity could prevent cognitive impairment caused by PM_2.5.

Alzheimer’s disease: insights and new prospects in disease pathophysiology, biomarkers and disease-modifying drugs

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases that affect millions of people worldwide, with both prevalence and incidence increasing with age. It is characterized by cognitive decline associated, specifically, with degeneration of cholinergic neurons. The problem of this disease is even more fundamental as the available therapies remain fairly limited and mainly focused on symptoms' relief. Although the aetiology of the disease remains elusive, two main pathological hallmarks are described: i) presence of neurofibrillary tangles formed by unfolded protein aggregates (hyperphosphorylated Tau protein) and ii) presence of extracellular aggregates of amyloid-beta peptide. Given the complexity surrounding the pathogenesis of the disease, several potential targets have been highlighted and interrelated upon its progression, such as oxidative stress and the accumulation of metal ions. Thus, advances have been made on the development of innovative multitarget therapeutical compounds to delay the disease progression and restore cell function. This review focuses the ongoing research on new insights and emerging disease-modifying drugs for AD treatment. Furthermore, classical and novel potential biomarkers for early diagnosis of the disease, and their role in assisting on the improvement of targeted therapies will also be approached.

Real-Time Detection and Visualization of Amyloid-β Aggregates Induced by Hydrogen Peroxide in Cell and Mouse Models of Alzheimer's Disease

Oxidative stress, caused by an imbalance between the production and the accumulation of reactive oxygen species (ROS), is a prominent cause of the neurotoxicity induced by aggregated amyloid-β (Aβ) in Alzheimer's disease (AD). Tools that can directly detect and monitor the presence and amount of Aβ-induced ROS are still lacking. We report herein the first Aβ-targeted ratiometric H₂O₂-responsive fluorescent probe for real-time detection and monitoring of the Aβ-induced H₂O₂ level in cell and AD mouse models. The H₂O₂-responsive probe is constructed based on a methylamino-substituted quinolinium-based cyanine as the fluorescence moiety and a phenylboronate ester as the sensing reaction site. This sensing probe exhibits a large emission wavelength shift of ∼87 nm upon reacting with H₂O₂, a high binding selectivity for Aβ, and a faster response toward H₂O₂ in the presence of Aβ, concomitant with an enhanced fluorescence intensity, hence greatly boosting the sensitivity of in-situ H₂O₂ detection. This biocompatible and nontoxic probe is capable of ratiometrically detecting and imaging endogenous H₂O₂ induced by Aβ in a neuronal cell model. Remarkably, this Aβ-targeted H₂O₂-responsive probe is also able to detect, monitor, and differentiate different Aβ-induced H₂O₂ levels in real time in different age groups of transgenic AD mice in which the cerebral H₂O₂ level increases age dependently concomitant with the plaque contents. Therefore, this smart probe can act as a powerful tool to diagnose high-risk subjects and diseased brains of AD and to further study the role of ROS in AD pathology.

Inhibition of Pro-Inflammatory Microglia with Minocycline Improves Cognitive and Sleep-Wake Dysfunction Under Respiratory Stress in a Sporadic Model for Alzheimer's Disease

BACKGROUND

Neuroinflammation in Alzheimer's disease (AD) can occur due to excessive activation of microglia in response to the accumulation of amyloid-β peptide (Aβ). Previously, we demonstrated an increased expression of this peptide in the locus coeruleus (LC) in a sporadic model for AD (streptozotocin, STZ; 2 mg/kg, ICV). We hypothesized that the STZ-AD model exhibits neuroinflammation, and treatment with an inhibitor of microglia (minocycline) can reverse the cognitive, respiratory, sleep, and molecular disorders of this model.

OBJECTIVE

To evaluate the effect of minocycline treatment in STZ model disorders.

METHODS

We treated control and STZ-treated rats for five days with minocycline (30 mg/kg, IP) and evaluated cognitive performance, chemoreflex response to hypercapnia and hypoxia, and total sleep time. Additionally, quantification of Aβ, microglia analyses, and relative expression of cytokines in the LC were performed.

RESULTS

Minocycline treatment improved learning and memory, which was concomitant with a decrease in microglial cell density and re-establishment of morphological changes induced by STZ in the LC region. Minocycline did not reverse the STZ-induced increase in CO2 sensitivity during wakefulness. However, it restored the daytime sleep-wake cycle in STZ-treated animals to the same levels as those observed in control animals. In the LC, levels of A and expression of Il10, Il1b, and Mcp1 mRNA remained unaffected by minocycline, but we found a strong trend of minocycline effect on Tnf- α.

CONCLUSION

Our findings suggest that minocycline effectively reduces microglial recruitment and the inflammatory morphological profile in the LC, while it recovers cognitive performance and restores the sleep-wake pattern impaired by STZ.

VANL-100 Attenuates Beta-Amyloid-Induced Toxicity in SH-SY5Y Cells

Antioxidants are being explored as novel therapeutics for the treatment of neurodegenerative diseases such as Alzheimer's disease (AD) through strategies such as chemically linking antioxidants to synthesize novel co-drugs. The main objective of this study was to assess the cytoprotective effects of the novel antioxidant compound VANL-100 in a cellular model of beta-amyloid (Aβ)-induced toxicity. The cytotoxic effects of Aβ in the presence and absence of all antioxidant compounds were measured using the 3-(4,5-dimethylthiazol-2-yl)2-5-diphenyl-2H-tetrazolium bromide (MTT) assay in SH-SY5Y cells in both pre-treatment and co-treatment experiments. In pre-treatment experiments, VANL-100, or one of its parent compounds, naringenin (NAR), alpha-lipoic acid (ALA), or naringenin + alpha-lipoic acid (NAR + ALA), was administrated 24 h prior to an additional 24-h incubation with 20 μM non-fibril or fibril Aβ_25-35. Co-treatment experiments consisted of simultaneous treatment with Aβ and antioxidants. Pre-treatment and co-treatment with VANL-100 significantly attenuated Aβ-induced cell death. There were no significant differences between the protective effects of VANL-100, NAR, ALA, and NAR + ALA with either form of Aβ, or in the effect of VANL-100 between 24-h pre-treatment and co-treatment. These results demonstrate that the novel co-drug VANL-100 is capable of eliciting cytoprotective effects against Aβ-induced toxicity.

Understanding the Intricate Role of Exosomes in Pathogenesis of Alzheimer's Disease

Alzheimer's disease causes loss of memory and deterioration of mental abilities is utmost predominant neurodegenerative disease accounting 70-80% cases of dementia. The appearance of plaques of amyloid-β and neurofibrillary tangles in the brain post-mortems of Alzheimer's patients established them as key participants in the etiology of Alzheimer's disease. Exosomes exist as extracellular vesicles of nano-size which are present throughout the body. Exosomes are known to spread toxic hyperphosphorylated tau and amyloid-β between the cells and are linked to the loss of neurons by inducing apoptosis. Exosomes have progressed from cell trashcans to multifunctional organelles which are involved in various functions like internalisation and transmission of macromolecules such as lipids, proteins, and nucleic acids. This review covers current findings on relationship of exosomes in biogenesis and angiogenesis of Alzheimer's disease and functions of exosomes in the etiology of AD. Furthermore, the roles of exosomes in development, diagnosis, treatment, and its importance as therapeutic targets and biomarkers for Alzheimer's disease have also been highlighted.

Recent Studies on Protective Effects of Walnuts against Neuroinflammation

Neuroinflammation plays a significant role in the aging process and the pathophysiology of neurodegenerative diseases, such as Alzheimer’s disease. Accordingly, possible therapeutic strategies aimed at anti-inflammatory effects may be beneficial to brain health. Walnut kernels contain large quantities of unsaturated fatty acids, peptides, and phenolic compounds that have anti-inflammatory effects. The long-term intake of walnuts has been found to improve cognitive function and memory in rats and humans. However, the modulatory effect of walnuts on neuroinflammation has received much less attention. This review focuses on the potential influence and main regulating mechanisms of walnuts and their active ingredients on neuroinflammation, including the regulation of microglia activation induced by amyloid β or lipopolysaccharides, inhibition of peripheral inflammation mediated by macrophages, reduction in oxidative stress by decreasing free radical levels and boosting antioxidant defenses, and control of gut microbes to maintain homeostasis. However, the majority of evidence of the beneficial effects of walnuts or their components on neuroinflammation and neurodegeneration comes from experimental work, whereas evidence from clinical studies on the beneficial effects is scarcer and less conclusive. This review aims to provide new insights into the neuroinflammation-regulating mechanisms and natural active ingredients of walnuts and the development of walnut-based functional foods for the alleviation of neurodegenerative diseases.

Trimethoxyflavones from Ocimum basilicum L. leaves improve long term memory in mice by modulating multiple pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Traditionally, Ocimum basilicum L. leaves (OB) are recommended for various brain disorders.

AIM OF THE STUDY

Scientific evidence highlights the cognition improvement capacity of Ocimum basilicum L. leave extract (OBE), however, the compound(s) responsible for this effect and the associated mechanism was not reported. The present study was, thus, designed to isolate and identify the compound responsible for memory improvement effects of OB and to delineate the associated mechanism of action.

MATERIALS AND METHODS

In-vitro acetylcholinesterase (AChE) inhibitory (Ellman method) and antioxidant (DPPH scavenging) assays guided fractionation was employed to isolate the bioactive compounds from OBE. The isolated compounds were characterised using spectroscopic techniques (FTIR, NMR and MS). In-silico and in-vivo [mouse model of scopolamine (SCOP) induced amnesia] investigations were used to substantiate the memory improvement effects of isolated compounds and to understand their mechanism of action.

RESULTS

AChE and DPPH assays guided fractionation of OBE lead to isolation of two pure compounds namely, 5,7-dihydroxy-3',4',5'-trimethoxyflavone (S1) and 3-hydroxy-3',4',5'-trimethoxyflavone (S2). Both S1 and S2 mitigated the cognitive impairment due to SCOP in mice by reducing brain AChE activity, TBARS, TNF-α, IL-1β, IL-6 and caspase-3 concentrations and elevating reduced glutathione and IL-10 levels; together with amelioration of brain hippocampus histopathological aberration (H and E staining). Moreover, the molecular docking of S1 and S2 at the active pockets of AChE and caspase-3 has shown good interactions with vital amino acid residues.

CONCLUSIONS

Our findings show that trimethoxy flavones are responsible for the memory improvement effect of OBE due to their anticholinergic, antioxidant, anti-inflammatory and anti-apoptotic properties. These maybe developed as valuable alternatives for management of cognitive disorders.

Dysfunctional Glucose Metabolism in Alzheimer’s Disease Onset and Potential Pharmacological Interventions

Alzheimer’s disease (AD) is the most common age-related dementia. The alteration in metabolic characteristics determines the prognosis. Patients at risk show reduced glucose uptake in the brain. Additionally, type 2 diabetes mellitus increases the risk of AD with increasing age. Therefore, changes in glucose uptake in the cerebral cortex may predict the histopathological diagnosis of AD. The shifts in glucose uptake and metabolism, insulin resistance, oxidative stress, and abnormal autophagy advance the pathogenesis of AD syndrome. Here, we summarize the role of altered glucose metabolism in type 2 diabetes for AD prognosis. Additionally, we discuss diagnosis and potential pharmacological interventions for glucose metabolism defects in AD to encourage the development of novel therapeutic methods.

The Neuroprotective Effect of GM-1 Ganglioside on the Amyloid-Beta-Induced Oxidative Stress in PC-12 Cells Mediated by Nrf-2/ARE Signaling Pathway

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β (Aβ) plaques, tau tangles, neuroinflammation, oxidative stress, and progressive memory deficits. Aβ deposition could exacerbate oxidative damage and cellular apoptosis. GM-1 ganglioside (GM-1) has previously been reported to exhibit neuroprotective effects in rodents and patients with AD. However, the substantial impacts and mechanism of GM-1 on Aβ-induced oxidative stress remain elusive. The present study used PC-12 pheochromocytoma cells treated with Aβ_25-35 peptide to construct the AD model in vitro. Aβ_25-35 administration alone inhibited cell viability and facilitated cell apoptosis in the range doses of 10 μM to 30 μM. At the same time, GM-1 supplementation promoted cell proliferation and rescued cell apoptosis in a dose-dependent fashion ranging from 5 to 30 μM. In parallel, GM-1 treatment alleviated Aβ-induced oxidative stress by increasing the level of antioxidant enzymes and decreasing the content of malondialdehyde (MDA). The nuclear factor-E2-related factor 2 (Nrf2) is a crucial mediator of antioxidant response. We reported herein that GM-1 could activate Nrf-2 in the PC-12 cells co-treated with Aβ_25-35, following with the activated expression of antioxidant response elements (ARE)-mediated antioxidant and detoxifying genes. Consistently, knock-down of Nrf-2 via siRNA abolished the beneficial decrease of Aβ-induced oxidative stress by GM-1 treatment, indicating that GM-1-improved oxidative stress was regulated by the Nrf-2 signaling pathway. Collectively, GM-1 could alleviate Aβ_25-35-induced oxidative damage mediated through the Nrf-2/ARE signaling pathway, which might be a potential agent for AD treatment.

A Preliminary Assessment of the Nutraceutical Potential of Acai Berry (Euterpe sp.) as a Potential Natural Treatment for Alzheimer's Disease

Alzheimer's disease (AD) is characterised by progressive neuronal atrophy and the loss of neuronal function as a consequence of multiple pathomechanisms. Current AD treatments primarily operate at a symptomatic level to treat a cholinergic deficiency and can cause side effects. Hence, there is an unmet need for healthier lifestyles to reduce the likelihood of AD as well as improved treatments with fewer adverse reactions. Diets rich in phytochemicals may reduce neurodegenerative risk and limit disease progression. The native South American palm acai berry (Euterpe oleraceae) is a potential source of dietary phytochemicals beneficial to health. This study aimed to screen the nutraceutical potential of the acai berry, in the form of aqueous and ethanolic extracts, for the ability to inhibit acetyl- and butyryl-cholinesterase (ChE) enzymes and scavenge free radicals via 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) or 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assays. In addition, this study aimed to quantify the acai berry's antioxidant potential via hydrogen peroxide or hydroxyl scavenging, nitric oxide scavenging, lipid peroxidation inhibition, and the ability to reduce ferric ions. Total polyphenol and flavonoid contents were also determined. Acai aqueous extract displayed a concentration-dependent inhibition of acetyl- and butyryl-cholinesterase enzymes. Both acai extracts displayed useful concentration-dependent free radical scavenging and antioxidant abilities, with the acai ethanolic extract being the most potent antioxidant and displaying the highest phenolic and flavonoid contents. In summary, extracts of the acai berry contain nutraceutical components with anti-cholinesterase and antioxidant capabilities and may therefore provide a beneficial dietary component that limits the pathological deficits evidenced in AD.

Astrocyte Reaction to Catechol-Induced Cytotoxicity Relies on the Contact with Microglia Before Isolation

Astrocytes preserve the brain microenvironment homeostasis in order to protect other brain cells, mainly neurons, against damages. Glial cells have specific functions that are important in the context of neuronal survival in different models of central nervous system (CNS) diseases. Microglia are among these cells, secreting several molecules that can modulate astrocyte functions. Although 1,2-dihydroxybenzene (catechol) is a neurotoxic monoaromatic compound of exogenous origin, several endogenous molecules also present the catechol group. This study compared two methods to obtain astrocyte-enriched cultures from newborn Wistar rats of both sexes. In the first technique (P1), microglial cells began to be removed early 48 h after primary mixed glial cultures were plated. In the second one (P2), microglial cells were late removed 7 to 10 days after plating. Both cultures were exposed to catechol for 72 h. Catechol was more cytotoxic to P1 cultures than to P2, decreasing cellularity and changing the cell morphology. Microglial-conditioned medium (MCM) protected P1 cultures and inhibited the catechol autoxidation. P2 cultures, as well as P1 in the presence of 20% MCM, presented long, dense, and fibrillary processes positive for glial fibrillary acidic protein, which retracted the cytoplasm when exposed to catechol. The Ngf and Il1beta transcription increased in P1, meanwhile astrocytes expressed more Il10 in P2. Catechol decreased Bdnf and Il10 in P2 cultures, and it decreased the expression of Il1beta in both conditions. A prolonged contact with microglia before isolation of astrocyte-enriched cultures modifies astrocyte functions and morphology, protecting these cells against catechol-induced cytotoxicity.

Rational drug design strategies for the development of promising multi-target directed indole hybrids as Anti-Alzheimer agents

Alzheimer's disease (AD) is a neurological disorder that leads to dementia i.e., progressive memory loss accompanied with worsening of thinking ability of an individual. The cause of AD is not fully understood but it progresses with age where brain cells gradually die over time. According to the World Health Organization (WHO), currently 50 million people worldwide are affected by dementia and 60-70% of the cases belong to AD. Cumulative research over the past few decades have shown that molecules that act at a single target possess limited efficacy since these investigational drugs are not able to act against complex pathologies and thus do not provide permanent cure. Designing of multi-target directed ligands (MTDLs) appears to be more beneficial and a rational approach to treat chronic complex diseases including neurodegenerative diseases. Recently, MTDLs are being extensively researched by the medicinal chemists for the development of drugs for the treatment of various multifactorial diseases. Indole is one of the privileged scaffolds which is considered as an essential mediator between the gut-brain axis because of its neuroprotective, anti-inflammatory, β-amyloid anti-aggregation and antioxidant activities. Herein, we have reviewed the potential of some indole-hybrids acting at multiple targets in the pathogenesis of AD. We have reviewed research articles from the year 2014-2021 from various scientific databases and highlighted the synthetic strategies, mechanisms of neuroprotection, toxicity, structure activity relationships and molecular docking studies of various indole-hybrid derivatives. This literature review of published data on indole derivatives indicated that developing indole hybrids have improved the pharmacokinetic profile with lower toxicity, provided synergistic effect, helped to develop more potent compounds and prevented drug-drug interactions. It is evident that this class of compounds have potential to inhibit multiple enzymes targets involved in the pathogenesis of AD and therefore indole hybrids as MTDLs may play an important role in the development of anti-AD molecules.

Passion fruit seed extract protects beta-amyloid-induced neuronal cell death in a differentiated human neuroblastoma SH-SY5Y cell model

Alzheimer's disease (AD) is a progressive neurodegenerative disease with accompanying perceptive disorder. We previously reported that decreasing levels of brain-derived neurotrophic factor (BDNF) promoted beta-amyloid (Aβ)-induced neuronal cell death in neuron-like differentiated SH-SY5Y (ndSH-SY5Y) human neuroblastoma cells in an AD mimic cell model. We investigated the neuroprotective effects of passion fruit seed extract (PFSE) and one of the main stilbene compounds, piceatannol, in an AD cell model using ndSH-SY5Y cells. Both PFSE and piceatannol were found to protect Aβ-induced neurite fragmentation in the cell model (protection efficacy; 34% in PFSE and 36% in piceatannol). In addition, both PFSE and piceatannol suppress Aβ-induced neuronal cell death in the cell model (inhibitory effect; 27% in PFSE and 32% in piceatannol). Our study is the first to report that piceatannol-rich PFSE can repress Aβ-induced neuronal cell death by protecting against neurite fragmentation in the AD human cell model. These findings suggest that piceatannol-rich PFSE can be considered a potentially neuroprotective functional food for both prevention and treatment of AD.

Oxidative stress: The core pathogenesis and mechanism of Alzheimer's disease

As the number of patients with Alzheimer's disease (AD) increases, it brings great suffering to their families and causes a heavy socioeconomic burden to society. A vast amount of funds and a mass of research have been devoted to elucidating the pathology of AD. However, the main pathogenesis is still elusive, and its mechanism is not completely clear. Research on the mechanisms of AD mainly focuses on the amyloid cascade, tau protein, neuroinflammation, metal ions, and oxidative stress hypotheses. Oxidative stress is as a bridge that connects the different hypotheses and mechanisms of AD. It is a process that causes neuronal damage and occurs in various pathways. Oxidative stress plays a critical role in AD and can even be considered a crucial central factor in the pathogenesis of AD. Previous reviews have also summarized the role of oxidative stress in AD, but these mainly review a specific signaling pathway. Taking oxidative stress as the central point, this review comprehensively expands on the roles of oxidative stress that are involved in the pathogenesis of AD. The vivid and easy-to-understand figures systematically clarify the connected roles of oxidative stress in AD and allow readers to further understand oxidative stress and AD.

Longitudinal Trajectories of Memory Performance in Patients with Early-Stage Breast Cancer

Background. While breast cancer and its treatments may affect cognition, the longitudinal trajectories of cognition among those receiving differing cancer treatment types remain poorly understood. Prior research suggests hippocampal-prefrontal cortex network integrity may influence cognition, although how this network predicts performance over time remains unclear. Methods. We conducted a prospective trial including 69 patients with early-stage breast cancer receiving adjuvant therapy and 12 controls. Longitudinal cognitive testing was conducted at four visits: pretreatment-baseline, 6-7 months, 14-15 months, and 23-24 months. Cognitive composite scores of episodic memory, executive functioning, and processing speed were assessed at each timepoint. Baseline structural MRI was obtained in a subset of these participants, and hippocampal and prefrontal cortex regional volumes were extracted. Results. Longitudinal linear mixed modeling revealed significant group by time interactions on memory performance, controlling for age and education. Post hoc analyses revealed this effect was driven by patients treated with chemotherapy or chemotherapy plus hormone therapy, who demonstrated the least improvement in memory scores over time. Treatment group did not significantly influence the relationship between time and processing speed or executive functioning. Neither pretreatment hippocampal nor prefrontal volume differed between groups, and there were no significant group by time by baseline regional volume effects on cognition. Conclusion. Patients with early-stage breast cancer treated with chemotherapy or chemotherapy plus hormone therapy benefit less from practice effects seen in healthy controls on memory tests. Loss of longitudinal practice effect may be a new and clinically relevant measure for capturing patients’ experience of cognitive difficulties after treatment.

Tricyclodecan-9-yl-Xanthogenate (D609): Mechanism of Action and Pharmacological Applications

Tricyclodecan-9-yl xanthogenate (D609) is a synthetic tricyclic compound possessing a xanthate group. This xanthogenate compound is known for its diverse pharmacological properties. Over the last three decades, many studies have reported the biological activities of D609, including antioxidant, antiapoptotic, anticholinergic, anti-tumor, anti-inflammatory, anti-viral, anti-proliferative, and neuroprotective activities. Its mechanism of action is extensively attributed to its ability to cause the competitive inhibition of phosphatidylcholine (PC)-specific phospholipase C (PC-PLC) and sphingomyelin synthase (SMS). The inhibition of PCPLC or SMS affects secondary messengers with a lipidic nature, i.e., 1,2-diacylglycerol (DAG) and ceramide. Various in vitro/in vivo studies suggest that PCPLC and SMS inhibition regulate the cell cycle, block cellular proliferation, and induce differentiation. D609 acts as a pro-inflammatory cytokine antagonist and diminishes Aβ-stimulated toxicity. PCPLC enzymatic activity essentially requires Zn2+, and D609 might act as a potential chelator of Zn2+, thereby blocking PCPLC enzymatic activity. D609 also demonstrates promising results in reducing atherosclerotic plaque formation, post-stroke cerebral infarction, and cancer progression. The present compilation provides a comprehensive mechanistic insight into D609, including its chemistry, mechanism of action, and regulation of various pharmacological activities.