EGCG Nanoparticles Attenuate Aluminum Chloride Induced Neurobehavioral Deficits, Beta Amyloid and Tau Pathology in a Rat Model of Alzheimer's Disease

Development of nanomedicines for the treatment of Alzheimer's disease: Raison d'être, strategies, challenges and regulatory aspects

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive loss of memory. Presently, AD is challenging to treat with current drug therapy as their delivery to the brain is restricted by the presence of the blood-brain barrier. Nanomedicines, due to their size, high surface volume ratio, and ease of tailoring drug release characteristics, showed their potential to treat AD. The nanotechnology-based formulations for brain targeting are expected to enter the market in the near future. So, regulatory frameworks are required to ensure the quality, safety, and effectiveness of the nanomedicines to treat AD. In this review, we discuss different strategies, in-vitro blood-brain permeation models, in-vivo permeation assessment, and regulatory aspects for the development of nanomedicine to treat AD.

Effectiveness of epigallocatechin gallate nanoparticles on the in-vivo treatment of Alzheimer's disease in a rat/mouse model: a systematic review

BACKGROUND

Alzheimer's disease (AD) is a neurological disease that causes memory loss over time. Current therapies are limited and frequently inadequate. Epigallocatechin gallate (EGCG), has antioxidant, anti-inflammatory, antifibrosis, anti-remodeling and tissue-protective qualities that may be effective in treatment of different diseases, including AD. Because of nanoparticles' high surface area, they can enhance solubility, stability, pharmacokinetics and biodistribution, and diminish toxicities. Besides, lipid nanoparticles have a high binding affinity that can enhance the rate of drug transport across BBB. So, EGCG nanoparticles represent a promising treatment for AD.

OBJECTIVES

This systematic review sought to assess the efficacy of EGCG nanoparticles against AD in rat/mouse models.

METHODS

Study was conducted in accordance with PRISMA guidelines, and the protocol was registered in PROSPERO. Electronic databases were searched to discover relevant studies published up to October 2022.

RESULTS

Two studies met the inclusion criteria out of 1338 and were included in this systematic review. Collectively, the results indicate that EGCG has a significant potential for reducing AD pathology and improving cognitive deficits in rat/mouse models. The formulated particles were in the nanometer range, as indicated by TEM, with good particle size control and stability. EGCG nanoparticles showed superior pharmacokinetic characteristics and improved blood-brain barrier permeability, and increased brain bioavailability compared to free EGCG. Additionally, nanoEGCG were more effective in modulating oxidative stress than free formulation and decreased AChE in the cortex and hippocampus of AlCl3-treated rats.

CONCLUSION

This systematic analysis of the two studies included showed that EGCG nanoparticles are efficacious as a potential therapeutic intervention for AD in rat/mouse models. However, limited number of studies found indicates insufficient data in this research point that requires further investigation by experimental studies.

Docosahexaenoic Acid (DHA), Vitamin D3, and Probiotics Supplementation Improve Memory, Glial Reactivity, and Oxidative Stress Biomarkers in an Aluminum-Induced Cognitive Impairment Rat Model

Globally, the rise in neurodegenerative issues in tandem with shifts in lifestyle and aging population has prompted a search for effective interventions. Nutraceutical compounds have emerged as promising agents for addressing these challenges. This 60-day study on an aluminum-induced cognitive impairment rat model assessed three compounds and their combinations: probiotics (Prob, Lactobacillus plantarum [5 × 1010 CFU/day], and Lactobacillus acidophilus [5 × 1010 CFU/day]), docosahexaenoic acid (DHA, 23.8 mg/day), and vitamin D3 (VD3, 150 IU/day). Behavioral outcomes were evaluated by using the Morris water maze and novel object recognition tests. Glial activation was assessed through immunofluorescence analysis of GFAP/Iba1, and oxidative stress markers in brain tissue were determined by measuring the levels of Malondialdehyde (MDA) and Superoxide dismutase (SOD). The results demonstrated a progressive improvement in the learning and memory capacity. The aluminum group exhibited the poorest performance in the behavioral test, enhanced GFAP/Iba1 activation, and elevated levels of oxidative stress markers. Conversely, the DHA + Prob + VD3 treatment demonstrated the best performance in the Morris water maze. The combination of DHA + Prob + VD3 exhibited superior performance in the Morris water maze, accompanied by reduced levels of GFAP/Iba1 activation in DG/CA1 brain regions. Furthermore, DHA + Prob supplementation showed lower GFAP/Iba1 activation in the CA3 region and enhanced antioxidant activity. In summary, supplementing various nutraceutical combinations, including DHA, VD3, and Prob, displayed notable benefits against aluminum-induced cognitive impairment. These benefits encompassed memory enhancement, diminished MDA concentration, increased SOD activity, and reduced glial activation, as indicated by GFAP/Iba1 markers.

Betanin combined with virgin coconut oil inhibits neuroinflammation in aluminum chloride-induced toxicity in rats by regulating NLRP3 inflammasome

Background and aim

Activating NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) is crucial in the pathogenesis of Alzheimer's disease (AD). A multimodal treatment intervention is the most feasible way to alter the course of AD progression. Hence, the current study was conducted to study the combination of betanin (BET) and virgin coconut oil (VCO) on NLRP3 regulation in aluminum chloride-induced AD in Wistar rats.

Experimental procedure

BET (100,200 mg/kg) and VCO (1, 5 g/kg) alone and in combination (BET 100 mg/kg + VCO 1 g/kg and BET 200 mg/kg + VCO 5 g/kg) were given orally for 42 days. On day 21 and 42nd, the behavioral test was performed to check the animal's cognition. Acetylcholinesterase (AChE) activity, oxidative stress markers, estimation of NLRP3 and IL-1β, and histological examinations were conducted in the hippocampus (H) and cortex (C).

Results and conclusion

Treatment with BET and VCO alone or combined improved behavioral characteristics (MWM and PA p < 0.0001; EPM p = 0.5184), inhibited AChE activity (C, p = 0.0101; H, p < 0.0001), and lowered oxidative stress in the brain. Also, combination treatment restored the levels of NLRP3 (C, p = 0.0062; H, p < 0.0001) and IL1β (C, p = 0.0005; H, p = 0.0098). The combination treatment significantly reduced the degree of neuronal degeneration, amyloid deposition, and necrosis in the brain tissue. The current study revealed that the combination strategy effectively controlled neuroinflammation via modulation of the NLRP3 inflammasome pathway, paving the way for the new treatment.

Protective effect of a hydromethanolic extract from Fraxinus excelsior L. bark against a rat model of aluminum chloride-induced Alzheimer's disease: Relevance to its anti-inflammatory and antioxidant effects

ETHNOPHARMACOLOGICAL RELEVANCE

Fraxinus excelsior L. (FE), commonly known as the ash, belongs to the Oleaceae family and has shown several pharmacological and biological properties, such as antioxidant, immunomodulatory, neuroprotective, and anti-inflammatory effects. It has also attracted the most attention toward neuroinflammation. Moreover, FE bark and leaves have been used to treat neurological disorders, aging, neuropathic pain, urinary complaints, and articular pain in traditional and ethnomedicine. Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder resulting from the involvement of amyloid-beta, metal-induced oxidative stress, and neuroinflammation.

AIM OF THE STUDY

The objective of the current study was to assess the neuroprotective effects of hydromethanolic extract from FE bark in an AlCl3-induced rat model of AD.

MATERIALS AND METHODS

The maceration process was utilized to prepare the hydromethanolic extract of FE bark, and characterized by LC-MS/MS. To assess the anti-AD effects of the FE extract, rats were categorized into five different groups, AlCl3; normal control; FE-treated groups at 50, 100, and 200 mg/kg. Passive avoidance learning test, Y-maze, open field, and elevated plus maze behavioral tests were evaluated on days 7 and 14 to analyze the cognitive impairments. Zymography analysis, biochemical tests, and histopathological changes were also followed in different groups.

RESULTS

LC-MS/MS analysis indicated the presence of coumarins, including isofraxidin7-O-diglucoside in the methanolic extract of FE as a new isofraxidin derivative in this genus. FE significantly improved memory and cognitive function, maintained weight, prevented neuronal damages, and preserved the hippocampus's histological features, as demonstrated by behavioral tests and histopathological analysis. FE increased anti-inflammatory MMP-2 activity, whereas it decreased that of inflammatory MMP-9. Moreover, FE increased plasma antioxidant capacity by enhancing CAT and GSH while decreasing nitrite levels in the serum of treated groups. In comparison between the treated groups, the rats that received high doses of the FE extract (200 mg/kg) showed the highest therapeutic effect.

CONCLUSION

FE rich in coumarins could be an effective anti-AD adjunct agent, passing through antioxidant and anti-inflammatory pathways. These results encourage further studies for the development of this extract as a promising agent in preventing, managing, or treating AD and related diseases.

EGCG-based nanoparticles: synthesis, properties, and applications

(-)-Epigallocatechin-3-gallate (EGCG) is a natural phenolic substance found in foods and beverages (especially tea) that exhibits a broad spectrum of biological activities, including antioxidant, antimicrobial, anti-obesity, anti-inflammatory, and anti-cancer properties. Its potential in cardiovascular and brain health has garnered significant attention. However, its clinical application remains limited due to its poor physicochemical stability and low oral bioavailability. Nanotechnology can be used to improve the stability, efficacy, and pharmacokinetic profile of EGCG by encapsulating it within nanoparticles. This article reviews the interactions of EGCG with various compounds, the synthesis of EGCG-based nanoparticles, the functional attributes of these nanoparticles, and their prospective applications in drug delivery, diagnosis, and therapy. The potential application of nanoencapsulated EGCG in functional foods and beverages is also emphasized. Top-down and bottom-up approaches can be used to construct EGCG-based nanoparticles. EGCG-based nanoparticles exhibit enhanced stability and bioavailability compared to free EGCG, making them promising candidates for biomedical and food applications. Notably, the non-covalent and covalent interactions of EGCG with other substances significantly contribute to the improved properties of these nanoparticles. EGCG-based nanoparticles appear to have a wide range of applications in different industries, but further research is required to enhance their efficacy and ensure their safety.

New bithiophene derivative attenuated Alzheimer's disease induced by aluminum in a rat model via antioxidant activity and restoration of neuronal and synaptic transmission

BACKGROUND

One of the hypotheses that leads to an increased incidence of Alzheimer's disease (AD) is the accumulation of aluminum in the brain's frontal cortex. The present study aimed to evaluate the therapeutic role of a novel bithiophene derivative at two doses against AlCl3-induced AD in a rat model.

METHODOLOGY

Adult male rats were divided into six groups, 18 rats each. Group 1: naïve animals, group 2: animals received a daily oral administration of bithiophene dissolved in DMSO (1 mg/kg) for 30 days every other day, groups 3-6: animals received a daily oral administration of AlCl3 (100 mg/kg/day) for 45 consecutive days. Groups 4 and 5 received an oral administration of low or high dose of the bithiophene (0.5 or 1 mg/kg, respectively). Group 6; Animals were treated with a daily oral dose of memantine (20 mg/kg) for 30 consecutive days.

MAIN FINDINGS

Al disturbed the antioxidant milieu, elevated the lipid peroxidation, and depleted the antioxidants. It also disturbed the synaptic neurotransmission by elevating the activities of acetylcholine esterase and monoamine oxidase resulting in the depletion of dopamine and serotonin and accumulation of glutamate and norepinephrine. Al also deteriorated the expression of genes involved in apoptosis and the production of amyloid-β plaques as well as phosphorylation of tau. The new bithiophene at the low dose reversed most of the previous deleterious effects of aluminum in the cerebral cortex and was in many instances superior to the reference drug; memantine.

CONCLUSION

Taking together, the bithiophene modulated the AD etiology through antioxidant activity, prevention of neuronal and synaptic loss, and probably mitigating the formation of amyloid-β plaques and phosphorylation of tau.

A novel Zebrafish model of Alzheimer's disease by Aluminium chloride; involving nitro-oxidative stress, neuroinflammation and cholinergic pathway

Alzheimer's disease (AD) is the most common form of dementia and is a progressive neurodegenerative disorder of the brain. Most AD experimental animal models are pharmacological or transgenic in origin. The existing pharmacological approaches for developing AD are poorly developed and most of them fail to replicate the complete characteristics of disease pathology. Developing a cost-effective and reliable experimental animal model will meet this research gap. Zebrafish (ZF) are progressively emerging as a powerful drug discovery disease model to evaluate central nervous system (CNS) disorders due to their homologous similarities to humans as well as cost-effectiveness. The present research is conceptualized to develop and evaluate a reliable ZF AD model using aluminum chloride (AlCl3). Chronic exposure of 0.04 mM of AlCl3 for 28 days increased the expression of amyloid-β, phosphorylated tau protein and senile plaque development in the ZF brain. The observed changes were associated with learning and memory impairment. Furthermore, decreased brain-derived neurotrophic factor (BDNF) level and elevated oxidative stress indices, pro-inflammatory cytokines levels and acetylcholine esterase (AChE) activity was observed upon exposure to AlCl3 in the ZF brain. Chronic exposure to 0.04 mM of AlCl3 would be a cost-effective ZF AD model for pharmacological screening and may also be used to unravel the molecular mechanism underlying the neuropathology of the disease.

Feasibility Study of Developing a Saline-Based Antiviral Nanoformulation Containing Lipid-Soluble EGCG: A Potential Nasal Drug to Treat Long COVID

A recent estimate indicates that up to 23.7 million Americans suffer from long COVID, and approximately one million workers may be out of the workforce each day due to associated symptoms, leading to a USD 50 billion annual loss of salary. Post-COVID (Long COVID) neurologic symptoms are due to the initial robust replication of SARS-CoV-2 in the nasal neuroepithelial cells, leading to inflammation of the olfactory epithelium (OE) and the central nervous system (CNS), and the OE becoming a persistent infection site. Previously, our group showed that Epigallocatechin-3-gallate-palmitate (EC16) nanoformulations possess strong antiviral activity against human coronavirus, suggesting this green tea-derived compound in nanoparticle formulations could be developed as an intranasally delivered new drug to eliminate the persistent SARS-CoV-2 infection, leading to restored olfactory function and reduced inflammation in the CNS. The objective of the current study was to determine the compatibility of the nanoformulations with human nasal primary epithelial cells (HNpECs).

METHODS

Nanoparticle size was measured using the ZetaView Nanoparticle Tracking Analysis (NTA) system; contact antiviral activity was determined by TCID50 assay for cytopathic effect on MRC-5 cells; post-infection inhibition activity was determined in HNpECs; and cytotoxicity for these cells was determined using an MTT assay. The rapid inactivation of OC43 (a β-coronavirus) and 229E (α-coronavirus) viruses was further characterized by transmission electron microscopy.

RESULTS

A saline-based nanoformulation containing 0.1% w/v EC16 was able to inactivate 99.9999% β-coronavirus OC43 on direct contact within 1 min. After a 10-min incubation of infected HNpECs with a formulation containing drug-grade EC16 (EGCG-4' mono-palmitate or EC16m), OC43 viral replication was inhibited by 99%. In addition, all nanoformulations tested for their effect on cell viability were comparable to normal saline, a regularly used nasal irrigation solution. A 1-min incubation of an EC16 nanoformulation with either OC43 or 229E showed an altered viral structure.

CONCLUSION

Nanoformulations containing EC16 showed properties compatible with nasal application to rapidly inactivate SARS-CoV-2 residing in the olfactory mucosa and to reduce inflammation in the CNS, pending additional formulation and safety studies.

Phytochemical Extract from Carica papaya Leaves and Punica granatum Seeds as Therapy Against Cognitive Impairment in a Murine Model

Mild cognitive impairment (MCI) is defined as inter-stage between normal cognitive aging and major neurocognitive disorder (MND). This state of decay is a crucial factor in treatment to prevent the progression to MND. In this study, our group developed a virtual screening process to evaluate 2568 phytochemical compounds against 5 key proteins associated with MCI and MND. As a result, two potential candidates were identified: carpaine, found in Carica papaya leaves, and punicalagin, present in Punica granatum. A model of cognitive impairment (CI) was developed in 10-month-old male Sprague Dawley rats by administering aluminum chloride (AlCl3) at a dose of 100 mg/kg/day for 30 days. After AlCl3 administration period, one of the groups received carpaine and punicalagin in a phytochemical extract (PE) by oral gavage for 30 days. Novel object recognition test (NOR) was assessed at three different time points (T1 - before CI, T2 - after CI, and T3 - after PE treatment). Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) were identified in the hippocampus of rats at the end of the study period. After administration of AlCl3, a reduction in discrimination index vs control rats (CI = 0.012 ± 0.08 vs Control = 0.076 ± 0.03), was observed. After phytochemical extract treatment, a significant increase in discrimination index values was observed in the PE group 0.4643 ± 0.13 vs CI group 0.012 ± 0.08. Additionally, the evaluation of immunohistochemistry showed an increase in GFAP positivity in the hippocampus of the CI groups, while a slight decrease was observed in the PE group. This work addressed a comprehensive methodology that utilized in silico tools to identify phytochemical compounds (carpaine and punicalagin) as potential candidates for affecting key proteins in CI. The phytochemical extract containing carpaine and punicalagin resulted in a trend in the decrease of GFAP expression in the hippocampus and improved recognition memory in rats with CI induced by age and AlCl3 administration.

Neuroprotective effects of a combination of Boswellia papyrifera and Syzygium aromaticum on AlCl3 induced Alzheimer's disease in male albino rat

Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by hippocampal, and cortical neuron deterioration, oxidative stress, and severe cognitive dysfunction. Aluminum is a neurotoxin inducer for cognitive impairments associated with AD. The treatment approaches for AD are unsatisfactory. Boswellia papyrifera and Syzygium aromaticum are known for their pharmacological assets, including antioxidant activity. Therefore, the current study explored the possible mitigating effects of a combination of Boswellia papyrifera and Syzygium aromaticum against aluminum chloride (AlCl3) induced AD. The AD model was established using AlCl3 (100 mg/kg), and the rats were orally administrated with Boswellia papyrifera or Syzygium aromaticum or a combination of them daily for 8 weeks. The Y-maze test was used to test cognition in the rats, while acetylcholinesterase (AChE) and oxidative stress markers were estimated in homogenates of the cerebral cortex and hippocampus. Also, the histopathological examination of the cortex and hippocampus were investigated. The results revealed that administration of either B. papyrifera or S. aromaticum extracts significantly improved the cognitive functions of AD rats, enhanced AChE levels, increased oxidative enzymes levels, including SOD and GSH, and reduced MDA levels in homogenates of the cerebral cortex and hippocampus and confirmed by improvement in histological examination. However, using a combination therapy gave better results compared to a single treatment. In conclusion, the present study provided primary evidence for using a combination of B. papyrifera and S. aromaticum to treat cognitive dysfunction associated with AlCl3 Induced AD by improving the AChE levels and modulating oxidative stress in the brain.

Nanoparticles loaded with natural medicines for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that disrupts cognitive function and severely affects the quality of life. Existing drugs only improve cognitive function and provide temporary relief of symptoms but do not stop or delay disease progression. Recently, natural medicines, especially Chinese herbal medicines, have gained attention in the treatment of AD due to their antioxidant, anti-inflammatory, and neuroprotective effects. However, conventional oral dosage forms lack brain specificity and have side effects that lead to poor patient compliance. Utilizing nanomedicine is a promising approach to improve brain specificity, bioavailability, and patient compliance. This review evaluates recent advances in the treatment of AD with nanoparticles containing various natural medicines. This review highlights that nanoparticles containing natural medicines are a promising strategy for the treatment of AD. It is believed that this technology can be translated into the clinic, thereby providing opportunities for AD patients to participate in social activities.

Controlled release of Clenbuterol from a hydroxyapatite carrier for the treatment of Alzheimer's Disease

BACKGROUND

Alzheimer's disease is a neurodegenerative disorder, and Aβ aggregation is considered to be the central process implicated in its pathogenesis. Current treatments are faced by challenges such as serious side effects and reduced drug bioavailability. In this study, we developed a drug delivery system for intramuscular injection that uses cellular activity to achieve constant and long-term drug release.

METHODS

Synthesized mesoporous hydroxyapatite (SHAP) was prepared via co-precipitation, and hydrophobic surface modification using stearic acid was then used to load clenbuterol by physical absorption, thus creating the drug delivery system. Clenbuterol release was achieved through cellular activity, with macrophage uptake triggering lysosome/endosome disruption, cytoplasmic release, extracellular exocytosis, and subsequent systemic circulation.

RESULTS

We found that clenbuterol-loaded SHAP enabled sustained release for more than 2 weeks and effectively modulated inflammation, reduced Aβ oligomer-induced toxicity, and prevented Aβ aggregation.

CONCLUSIONS

Our findings suggest that treatment with clenbuterol loaded in this SHAP delivery system could be a promising strategy for treating Alzheimer's disease.

Neuromodulatory effect of vardenafil on aluminium chloride/D-galactose induced Alzheimer's disease in rats: emphasis on amyloid-beta, p-tau, PI3K/Akt/p53 pathway, endoplasmic reticulum stress, and cellular senescence

Dysregulation of protein homeostasis, proteostasis, is a distinctive hallmark of many neurodegenerative disorders and aging. Deleteriously, the accumulation of aberrant proteins in Alzheimer's disease (AD) is accompanied with a marked collapse in proteostasis network. The current study explored the potential therapeutic effect of vardenafil (VAR), a phosphodiesterase-5 inhibitor, in AlCl3/D-galactose (D-gal)-induced AD in rats and its possible underlying mechanisms. The impact of VAR treatment on neurobehavioral function, hippocampal tissue architecture, and the activity of the cholinergic system main enzymes were assessed utilizing VAR at doses of 0.3 mg/kg and 1 mg/kg. Additionally, the expression level of amyloid-beta and phosphorylated tau proteins in the hippocampus were figured out. Accordingly, VAR higher dose was selected to contemplate the possible underlying mechanisms. Intriguingly, VAR elevated the cyclic guanosine monophosphate level in the hippocampus and averted the repressed proteasome activity by AlCl3/D-gal; hence, VAR might alleviate the burden of toxic protein aggregates in AD. In addition, a substantial reduction in the activating transcription factor 6-mediated endoplasmic reticulum stress was demonstrated with VAR treatment. Notably, VAR counteracted the AlCl3/D-gal-induced depletion of nuclear factor erythroid 2-related factor 2 level. Moreover, the anti-senescence activity of VAR was demonstrated via its ability to restore the balance of the redox circuit. The modulation of phosphatidylinositol-3-kinase/protein kinase B/p53 pathway and the reduction of nuclear factor kappa B level, the key regulator of senescence-associated secretory phenotype mediators release, with VAR treatment were also elucidated. Altogether, these findings insinuate the possible therapeutic benefits of VAR in AD management.

Epigallocatechin Gallate: A Multifaceted Molecule for Neurological Disorders and Neurotropic Viral Infections

Epigallocatechin-3-gallate (EGCG), a polyphenolic moiety found in green tea extracts, exhibits pleiotropic bioactivities to combat many diseases including neurological ailments. These neurological diseases include Alzheimer's disease, multiple sclerosis, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. For instance, in the case of Alzheimer's disease, the formation of a β-sheet in the region of the 10th-21st amino acids was significantly reduced in EGCG-induced oligomeric samples of Aβ40. Its interference induces the formation of Aβ structures with an increase in intercenter-of-mass distances, reduction in interchain/intrachain contacts, reduction in β-sheet propensity, and increase in α-helix. Besides, numerous neurotropic viruses are known to instigate or aggravate neurological ailments. It exerts an effect on the oxidative damage caused in neurodegenerative disorders by acting on GSK3-β, PI3K/Akt, and downstream signaling pathways via caspase-3 and cytochrome-c. EGCG also diminishes these viral-mediated effects, such as EGCG delayed HSV-1 infection by blocking the entry for virions, inhibitory effects on NS3/4A protease or NS5B polymerase of HCV and potent inhibitor of ZIKV NS2B-NS3pro/NS3 serine protease (NS3-SP). It showed a reduction in the neurotoxic properties of HIV-gp120 and Tat in the presence of IFN-γ. EGCG also involves numerous viral-mediated inflammatory cascades, such as JAK/STAT. Nonetheless, it also inhibits the Epstein-Barr virus replication protein (Zta and Rta). Moreover, it also impedes certain viruses (influenza A and B strains) by hijacking the endosomal and lysosomal compartments. Therefore, the current article aims to describe the importance of EGCG in numerous neurological diseases and its inhibitory effect against neurotropic viruses.

Effect of exercise on the hypothalamic-pituitary-gonadal axis in a rat model of Alzheimer's disease

Hypothalamic-pituitary-gonadal (HPG) axis dysregulation was suggested to play a crucial role in Alzheimer's disease (AD). This study investigated the effects of exercise on HPG hormones in an AD rat model, as a possible mechanism underlying the favorable effect of exercise on AD. Forty male Wistar albino rats 2-3 months old were subdivided randomly into two groups (n = 20 each): AD group (injected intraperitoneally with aluminum chloride (70 mg/kg/day) for 6 weeks) and Control group. Each group was subdivided into exercised or non-exercised group (n = 10 each). Exercised groups were subjected to a swimming protocol (60 min/day, 5 days/week, 4 weeks). Serum HPG hormones, hippocampal β-amyloid levels and Morris water-maze cognition were assessed. Results demonstrated higher levels of β-amyloid, gonadotropin releasing hormone (GnRH), luteinizing hormone (LH) and follicle stimulating hormone (FSH) together with lower testosterone levels and cognitive impairment in the AD rats compared to controls. Β-amyloid levels negatively correlated with testosterone levels and positively correlated with GnRH, LH and FSH among the AD rats. Higher testosterone and lower GnRH, LH, FSH and β-amyloid levels, as well as cognitive improvement, were observed in the exercised compared to non-exercised AD rats, suggesting a modulatory role of exercise training on AD-associated HPG axis dysregulation.

Alzheimer's Disease and Green Tea: Epigallocatechin-3-Gallate as a Modulator of Inflammation and Oxidative Stress

Alzheimer's disease (AD) is the most common cause of dementia, characterised by a marked decline of both memory and cognition, along with pathophysiological hallmarks including amyloid beta peptide (Aβ) accumulation, tau protein hyperphosphorylation, neuronal loss and inflammation in the brain. Additionally, oxidative stress caused by an imbalance between free radicals and antioxidants is considered one of the main risk factors for AD, since it can result in protein, lipid and nucleic acid damage and exacerbate Aβ and tau pathology. To date, there is a lack of successful pharmacological approaches to cure or even ameliorate the terrible impact of this disease. Due to this, dietary compounds with antioxidative and anti-inflammatory properties acquire special relevance as potential therapeutic agents. In this context, green tea, and its main bioactive compound, epigallocatechin-3-gallate (EGCG), have been targeted as a plausible option for the modulation of AD. Specifically, EGCG acts as an antioxidant by regulating inflammatory processes involved in neurodegeneration such as ferroptosis and microglia-induced cytotoxicity and by inducing signalling pathways related to neuronal survival. Furthermore, it reduces tau hyperphosphorylation and aggregation and promotes the non-amyloidogenic route of APP processing, thus preventing the formation of Aβ and its subsequent accumulation. Taken together, these results suggest that EGCG may be a suitable candidate in the search for potential therapeutic compounds for neurodegenerative disorders involving inflammation and oxidative stress, including Alzheimer's disease.

Shared Genes of PPARG and NOS2 in Alzheimer’s Disease and Ulcerative Colitis Drive Macrophages and Microglia Polarization: Evidence from Bioinformatics Analysis and Following Validation

Emerging evidence shows that peripheral systemic inflammation, such as inflammatory bowel disease (IBD), has a close even interaction with central nervous disorders such as Alzheimer’s disease (AD). This study is designed to further clarify the relationship between AD and ulcerative colitis (UC, a subclass of IBD). The GEO database was used to download gene expression profiles for AD (GSE5281) and UC (GSE47908). Bioinformatics analysis included GSEA, KEGG pathway, Gene Ontology (GO), WikiPathways, PPI network, and hub gene identification. After screening the shared genes, qRT-PCR, Western blot, and immunofluorescence were used to verify the reliability of the dataset and further confirm the shared genes. GSEA, KEGG, GO, and WikiPathways suggested that PPARG and NOS2 were identified as shared genes and hub genes by cytoHubba in AD and UC and further validated via qRT-PCR and Western blot. Our work identified PPARG and NOS2 are shared genes of AD and UC. They drive macrophages and microglia heterogeneous polarization, which may be potential targets for treating neural dysfunction induced by systemic inflammation and vice versa.

Effects of simultaneous versus post exposure epigallocatechin-3-gallate treatment on aluminum induced neurotoxicity in rat hippocampus: A multi-approach study

Chronic aluminium(Al) exposure can affect the antioxidant and glutaminergic systems through N-methyl-D-aspartate receptors (NMDAR). This study was aimed to investigate the neurotoxic effect of Al through different mechanisms in rat hippocampus and to evaluate the protective role of epigallocatechin gallate (EGCG), a well-known antioxidant, with simultaneous administration of Al,as well as post-treatment after Al exposure.For this purpose, aluminum chloride(AlCl₃) was administered simultaneously with two different EGCG doses for 8 weeks as the first part of the study.In the second part of the study, after 4 weeks of AlCl₃ pre-administration, two different EGCG doses were also administered during four additional weeks as post-treatment.Al administration led to oxidative stress and increased acetylcholinesterase levels.NMDAR subunit mRNA expressions were down-regulated by Al, which was apparent in NMDAR1/2B subunits.Simultaneous EGCG treatment has shown a better neuroprotective effect in terms of these mechanisms and represents novel approach for the prevention of neurodegenerative diseases likely to be induced by Al.

Modulating Inflammation-Mediated Diseases via Natural Phenolic Compounds Loaded in Nanocarrier Systems

The global increase and prevalence of inflammatory-mediated diseases have been a great menace to human welfare. Several works have demonstrated the anti-inflammatory potentials of natural polyphenolic compounds, including flavonoid derivatives (EGCG, rutin, apigenin, naringenin) and phenolic acids (GA, CA, etc.), among others (resveratrol, curcumin, etc.). In order to improve the stability and bioavailability of these natural polyphenolic compounds, their recent loading applications in both organic (liposomes, micelles, dendrimers, etc.) and inorganic (mesoporous silica, heavy metals, etc.) nanocarrier technologies are being employed. A great number of studies have highlighted that, apart from improving their stability and bioavailability, nanocarrier systems also enhance their target delivery, while reducing drug toxicity and adverse effects. This review article, therefore, covers the recent advances in the drug delivery of anti-inflammatory agents loaded with natural polyphenolics by the application of both organic and inorganic nanocarriers. Even though nanocarrier technology offers a variety of possible anti-inflammatory advantages to naturally occurring polyphenols, the complexes' inherent properties and mechanisms of action have not yet been fully investigated. Thus, expanding the quest on novel natural polyphenolic-loaded delivery systems, together with the optimization of complexes' activity toward inflammation, will be a new direction of future efforts.

Virus-Like Cytosolic and Cell-Free Oxidatively Damaged Nucleic Acids Likely Drive Inflammation, Synapse Degeneration, and Neuron Death in Alzheimer's Disease

Oxidative stress, inflammation, and amyloid-β are Alzheimer's disease (AD) hallmarks that cause each other and other AD hallmarks. Most amyloid-β-lowering, antioxidant, anti-inflammatory, and antimicrobial AD clinical trials failed; none stopped or reversed AD. Although signs suggest an infectious etiology, no pathogen accumulated consistently in AD patients. Neuropathology, neuronal cell culture, rodent, genome-wide association, epidemiological, biomarker, and clinical studies, plus analysis using Hill causality criteria and revised Koch's postulates, indicate that the virus-like oxidative damage-associated molecular-pattern (DAMP) cytosolic and cell-free nucleic acids accumulated in AD patients' brains likely drive neuroinflammation, synaptotoxicity, and neurotoxicity. Cytosolic oxidatively-damaged mitochondrial DNA accumulated outside mitochondria dose-dependently in preclinical AD and AD patients' hippocampal neurons, and in AD patients' neocortical neurons but not cerebellar neurons or glia. In oxidatively-stressed neural cells and rodents' brains, cytosolic oxidatively-damaged mitochondrial DNA accumulated and increased antiviral and inflammatory proteins, including cleaved caspase-1, interleukin-1β, and interferon-β. Cytosolic double-stranded RNA and DNA are DAMPs that induce antiviral interferons and/or inflammatory proteins by oligomerizing with various innate-immune pattern-recognition receptors, e.g., cyclic GMP-AMP synthase and the nucleotide-binding-oligomerization-domain-like-receptor-pyrin-domain-containing-3 inflammasome. In oxidatively-stressed neural cells, cytosolic oxidatively-damaged mitochondrial DNA caused synaptotoxicity and neurotoxicity. Depleting mitochondrial DNA prevented these effects. Additionally, cell-free nucleic acids accumulated in AD patients' blood, extracellular vesicles, and senile plaques. Injecting cell-free nucleic acids bound to albumin oligomers into wild-type mice's hippocampi triggered antiviral interferon-β secretion; interferon-β injection caused synapse degeneration. Deoxyribonuclease-I treatment appeared to improve a severe-AD patient's Mini-Mental Status Exam by 15 points. Preclinical and clinical studies of deoxyribonuclease-I and a ribonuclease for AD should be prioritized.

Sarcococca saligna ameliorated D-galactose induced neurodegeneration through repression of neurodegenerative and oxidative stress biomarkers

Sarcococca saligna is a valuable source of bioactive secondary metabolites exhibiting antioxidant, anti-inflammatory and acetylcholinesterase inhibitory activities. The study was intended to explore the therapeutic pursuits of S. saligna in amelioration of cognitive and motor dysfunctions induced by D-galactose and linked mechanistic pathways. Alzheimer's disease model was prepared by administration of D-galactose subcutaneous injection100 mg/kg and it was treated with rivastigmine (100 mg/kg, orally) and plant extract for 42 days. Cognitive and motor functions were evaluated by behavioral tasks and oxidative stress biomarkers. Level of acetylcholinesterase, reduced level of glutathione, protein and nitrite level, and brain neurotransmitters were analyzed in brain homogenate. The level of apoptosis regulator Bcl-2, Caspases 3 and heat shock protein HSP-70 in brain homogenates were analyzed by ELISA and colorimetric method, respectively. AChE, IL-1β, TNF-α, IL-1α and β secretase expressions were analyzed by RT-PCR. S. saligna dose dependently suppressed the neurodegenerative effects of D-galactose induced behavioral and biochemical impairments through modulation of antioxidant enzymes and acetylcholinesterase inhibition. S. saligna markedly (P < 0.05) ameliorated the level of brain neurotransmitters, Bcl-2, HSP-70 and Caspases-3 level. S. saligna at 500-1000 mg/kg considerably recovered the mRNA expression of neurodegenerative and neuro-inflammatory biomarkers, also evident from histopathological analysis. These findings suggest that S. saligna could be applicable in cure of Alzheimer's disease.

Aluminum Oxide Nanoparticles Impair Working Memory and Neuronal Activity through the GSK3β/BDNF Signaling Pathway of Prefrontal Cortex in Rats

Studies demonstrated that alumina nanoparticles (alumina NPs) impair spatial cognition and hippocampus-dependent synaptic plasticity. Although alumina NPs accumulate in the prefrontal cortex (PFC), their effects on PFC-mediated neuronal and cognitive function have been not yet documented. Here, alumina NPs (10 or 20 μg/kg of body weight) were bilaterally injected into the medial PFC (mPFC) of adult rats, and the levels of glycogen synthase kinase 3β (GSK3β) and the brain-derived neurotrophic factor (BDNF) were detected. The PFC-dependent working memory task with one-minute or three-minute delay time was conducted. Meanwhile, the neuronal correlates of working memory performance were recorded. The specific expression of neuronal BDNF was assessed by colabeled BDNF expression with the neuronal nuclear antigen (NeuN). Whole-cell patch-clamp recordings were employed to detect neuronal excitability. Intra-mPFC alumina NP infusions significantly enhanced the expression of GSK3β but reduced the phosphorylation of GSK3β (pGSK3β) and BDNF levels more severely at a dose of 20 μg/kg. Alumina NPs acted in a dose-dependent manner to impair working memory. The neuronal expression of BDNF in the 20 μg/kg group was markedly declined compared with the 10 μg/kg group. During the delay time, the neuronal frequency of pyramidal cells but not interneurons was significantly weakened. Furthermore, both the frequency and amplitude of the excitatory postsynaptic currents (EPSCs) were descended in the mPFC slices. Additionally, the infusion of GSK3β inhibitor SB216763 or BDNF could effectively attenuate the impairments in neuronal correlate, neuronal activity, and working memory. From the perspective of the identified GSK3β/BDNF pathway, these findings demonstrated for the first time that alumina NPs exposure can be a risk factor for prefrontal neuronal and cognitive functions.

Mushroom Natural Products in Neurodegenerative Disease Drug Discovery

The variety of drugs available to treat neurodegenerative diseases is limited. Most of these drug's efficacy is restricted by individual genetics and disease stages and usually do not prevent neurodegeneration acting long after irreversible damage has already occurred. Thus, drugs targeting the molecular mechanisms underlying subsequent neurodegeneration have the potential to negate symptom manifestation and subsequent neurodegeneration. Neuroinflammation is a common feature of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis, and is associated with the activation of the NLRP3 inflammasome, which in turn leads to neurodegeneration. Inflammasome activation and oligomerisation is suggested to be a major driver of disease progression occurring in microglia. With several natural products and natural product derivatives currently in clinical trials, mushrooms have been highlighted as a rich and largely untapped source of biologically active compounds in both in vitro and in vivo neurodegenerative disease models, partially supported by successful clinical trial evaluations. Additionally, novel high-throughput methods for the screening of natural product compound libraries are being developed to help accelerate the neurodegenerative disease drug discovery process, targeting neuroinflammation. However, the breadth of research relating to mushroom natural product high-throughput screening is limited, providing an exciting opportunity for further detailed investigations.

Protective effect of Allium atroviolaceum-synthesized SeNPs on aluminum-induced brain damage in mice

This study evaluated the possible neuroprotective effect of Allium atroviolaceum extract (AaE)-synthesized selenium nanoparticles (SeNPs) on aluminum (Al)-induced neurotoxicity in mice, explaining the likely mechanisms. Mice were divided into five groups: G1, control; G2, AaE group that received AaE (200 mg/kg) for 4 weeks; and groups 3, 4, and 5 received AlCl3 (100 mg/kg) for 3 weeks. After that, G4 received AaE (200 mg/kg), and G5 received SeNPs-AaE (0.5 mg/kg) for another 1 week. Exposure to AlCl3 boosted oxidative damage in brain tissue as evidenced by a reduction in glutathione concentrations and other antioxidant enzymes along with increased lipid peroxidation and nitric oxide levels. There was also a rise in the concentrations of interleukin-1β, TNF-α, and cyclooxygenase-II activities. AlCl3-treated mice showed reduced brain-derived neurotrophic factor (BDNF) and dopamine levels, increased acetylcholinesterase (AChE) activity, and reduced Bcl-2, and Bax, and caspase-3 activities. Treatment with SeNPs-AaE significantly reduced markers of oxidative stress, inflammation, and apoptosis. In addition, in SeNPs-AaE-treated rats, levels of BDNF and dopamine were significantly increased along with a reduction in AChE as compared with the AlCl3 group. Therefore, our results indicate that SeNPs-AaE has a potential neuroprotective effect against Al-mediated neurotoxic effects because of its powerful antioxidant, anti-inflammatory, anti-apoptotic, and neuromodulatory activities.

Green Tea Catechins Attenuate Neurodegenerative Diseases and Cognitive Deficits

Neurodegenerative diseases exert an overwhelming socioeconomic burden all around the globe. They are mainly characterized by modified protein accumulation that might trigger various biological responses, including oxidative stress, inflammation, regulation of signaling pathways, and excitotoxicity. These disorders have been widely studied during the last decade in the hopes of developing symptom-oriented therapeutics. However, no definitive cure has yet been discovered. Tea is one of the world's most popular beverages. The same plant, Camellia Sinensis (L.).O. Kuntze, is used to make green, black, and oolong teas. Green tea has been most thoroughly studied because of its anti-cancer, anti-obesity, antidiabetic, anti-inflammatory, and neuroprotective properties. The beneficial effect of consumption of tea on neurodegenerative disorders has been reported in several human interventional and observational studies. The polyphenolic compounds found in green tea, known as catechins, have been demonstrated to have many therapeutic effects. They can help in preventing and, somehow, treating neurodegenerative diseases. Catechins show anti-inflammatory as well as antioxidant effects via blocking cytokines' excessive production and inflammatory pathways, as well as chelating metal ions and free radical scavenging. They may inhibit tau protein phosphorylation, amyloid beta aggregation, and release of apoptotic proteins. They can also lower alpha-synuclein levels and boost dopamine levels. All these factors have the potential to affect neurodegenerative disorders. This review will examine catechins' neuroprotective effects by highlighting their biological, pharmacological, antioxidant, and metal chelation abilities, with a focus on their ability to activate diverse cellular pathways in the brain. This review also points out the mechanisms of catechins in various neurodegenerative and cognitive diseases, including Alzheimer's, Parkinson's, multiple sclerosis, and cognitive deficit.

Epigallocatechin-3-gallate attenuates cyclophosphamide-induced damage in mouse ovarian tissue via suppressing inflammation, apoptosis, and expression of phosphorylated Akt, FOXO3a and rpS6

This study was conducted to evaluate the protective effects of epigallocatechin-3-gallate (EGCG) against ovarian toxicity in cyclophosphamide-treated mice and to verify the possible involvement of phosphorylated Akt, FOXO3a and rpS6 in the EGCG actions. Mice received saline solution (i.p.; control) or a single dose of cyclophosphamide (200 mg/kg body weight, i.p.) or mice were pretreated with N-acetylcysteine (150 mg/kg body weight, i.p.; positive control) or with EGCG (5, 25 or 50 mg/kg body weight, i.p.) once daily for three days followed by injection with single dose of cyclophosphamide (200 mg/kg body weight, i.p.). Thereafter, the mice were euthanized, and the ovaries were harvested and destined to histological (follicular morphology and activation), immunohistochemistry (cleaved caspase-3 and TNF-α) and fluorescence (mitochondrial activity and GSH concentrations) analyses. Furthermore, we examined the participation of p-Akt, p-FOXO3a and p-rpS6 in the protective effects of EGCG in cyclophosphamide-induced ovarian damage by immunohistochemical staining. The results showed that pretreatment with N-acetylcysteine or EGCG at 25 and 50 mg/kg before cyclophosphamide administration preserved the normal follicular morphology, prevented primordial follicle loss, reduced atresia, inflammation, and mitochondrial damage, and increased GSH concentrations compared to the only cyclophosphamide treatment. Additionally, pretreatment with 25 mg/kg EGCG regulated phosphorylated Akt, FOXO3a and rpS6 after cyclophosphamide treatment. In conclusion, short-time pretreatment with 25 mg/kg EGCG can prevent follicle loss in cyclophosphamide-treated mice by reducing oxidative damage, inflammation, and apoptosis, and regulating of p-Akt, p-FOXO3a and p-rpS6.

The Role of a Pathological Interaction between β-amyloid and Mitochondria in the Occurrence and Development of Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases in existence. It is characterized by an impaired cognitive function that is due to a progressive loss of neurons in the brain. Extracellular β-amyloid (Aβ) plaques are the main pathological features of the disease. In addition to abnormal protein aggregation, increased mitochondrial fragmentation, altered expression of the genes involved in mitochondrial biogenesis, disruptions in the ER-mitochondria interaction, and mitophagy are observed. Reactive oxygen species are known to affect Aβ expression and aggregation. In turn, oligomeric and aggregated Aβ cause mitochondrial disorders. In this review, we summarize available knowledge about the pathological effects of Aβ on mitochondria and the potential molecular targets associated with proteinopathy and mitochondrial dysfunction for the pharmacological treatment of Alzheimer's disease.

Therapeutic nanotechnologies for Alzheimer's disease: a critical analysis of recent trends and findings

Alzheimer's Disease (AD) is an irreversible neurodegenerative disease for which no disease modifying therapies are presently available. Besides the identification of pathological targets, AD presents numerous clinical and pharmacological challenges such as efficient active delivery to the central nervous system, cell targeting, and long-term dosing. Nanoparticles have been explored to overcome some of these challenges as drug delivery vehicles or drugs themselves. However, early promises have failed to materialize as no nanotechnology-based product has been able to reach the market and very few have moved past preclinical stages. In this review, we perform a critical analysis of the past decade's research on nanomedicine-based therapies for AD at the preclinical and clinical stages. The main obstacles to nanotechnology products and the most promising approaches were also identified, including renewed promise with gene editing, gene modulation, and vaccines.

A comprehensive review on the prevention and regulation of Alzheimer's disease by tea and its active ingredients

Alzheimer's disease (AD) has brought a heavy burden to society as a representative neurodegenerative disease. The etiology of AD combines multiple factors, concluding family, gender, head trauma, diseases and social psychology. There are multiple hypotheses explaining the pathogenesis of AD such as β-amyloid (Aβ) deposition and tau hyperphosphorylation, which lead to extracellular amyloid plaques and neurofibrillary tangles in neurons. The existing therapeutic drugs have several disadvantages including single target, poor curative effect, and obvious side effects. Tea contains many bioactive components, such as tea polyphenols (TPP), L-theanine (L-TH), tea pigment, tea polysaccharides and caffeine. The epidemiological investigations have shown that drinking tea can reduce the risk of AD. The mechanisms of tea active ingredients in the prevention and regulation of AD includes reducing the generation and aggregation of Aβ; inhibiting tau aggregation and hyperphosphorylation; inhibiting neuronal apoptosis and regulate neurotransmitters; relieving oxidative stress and neuroinflammation as well as the regulation of intestinal flora. This review summarizes the different signaling pathways that tea active ingredients regulate AD. Furthermore, we propose the main limitations of current research and future research directions, hoping to contribute to the development of natural functional foods based on tea active ingredients in the prevention and treatment of AD.

Investigating a Curcumin-Loaded PLGA-PEG-PLGA Thermo-Sensitive Hydrogel for the Prevention of Alzheimer’s Disease

In Alzheimer’s disease (AD), the most common cause of dementia, patients generally forget to take pills or skip medication due to side effects, affecting the treatment efficacy. In this study, we combined a poly(lactic-co-glycolic acid), (PLGA)-poly(ethylene glycol), and (PEG)-PLGA thermo-sensitive hydrogel with curcumin (PGC) to deliver an intramuscular injection that could continuously release curcumin and maintain it at a constant level in blood to prevent AD development or progression. We evaluated the drug release profile and cytotoxicity of PGC and its effects on AD pathology through in vitro and in vivo studies and on cognitive function through an aluminum-chloride-induced AD rat model. In the in vitro study, PGC exhibited a lack of cytotoxicity, excellent anti-inflammatory and antioxidant properties, and microglial modulation. In the Morris water maze test, the PGC injection-administered AD rats presented well-focused searching behavior with the shortest swimming path and longest retention times in the quadrant where the platform was initially located. Furthermore, PGC reduced amyloid-beta aggregation and deposition and significantly increased hippocampal activity. This study demonstrated that intramuscular PGC injection can effectively prevent AD development or progression in rats without inducing toxicity; therefore, this strategy could help overcome the present challenges in AD management in humans.

Neurotoxic effects of aluminium exposure as a potential risk factor for Alzheimer's disease

Aluminium is one of the most widely distributed elements of the Earth's crust. Its routine use has resulted in excessive human exposure and due to the potential neurotoxic effects has attained a huge interest in recent years. Despite its ubiquitous abundance, aluminium has no crucial biological functions in the human body. Oxidative stress and neuroinflammatory effects are attributed to its neurotoxic manifestations implicated in Alzheimer's disease. In this review, we have discussed the neuroinflammatory and neurodegenerative events in the brain induced by aluminium exposure. We have highlighted the neurotoxic events caused by aluminium, such as oxidative stress, apoptosis, inflammatory events, calcium dyshomeostasis, Aβ deposition, and neurofibrillary tangle formation in the brain. In addition, the protective measures needed for prevention of aluminium-induced neuronal dysregulations have also been discussed.

Nanotechnology-Based Drug Delivery Strategies to Repair the Mitochondrial Function in Neuroinflammatory and Neurodegenerative Diseases

Mitochondria are vital organelles in eukaryotic cells that control diverse physiological processes related to energy production, calcium homeostasis, the generation of reactive oxygen species, and cell death. Several studies have demonstrated that structural and functional mitochondrial disturbances are involved in the development of different neuroinflammatory (NI) and neurodegenerative (ND) diseases (NI&NDDs) such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Remarkably, counteracting mitochondrial impairment by genetic or pharmacologic treatment ameliorates neurodegeneration and clinical disability in animal models of these diseases. Therefore, the development of nanosystems enabling the sustained and selective delivery of mitochondria-targeted drugs is a novel and effective strategy to tackle NI&NDDs. In this review, we outline the impact of mitochondrial dysfunction associated with unbalanced mitochondrial dynamics, altered mitophagy, oxidative stress, energy deficit, and proteinopathies in NI&NDDs. In addition, we review different strategies for selective mitochondria-specific ligand targeting and discuss novel nanomaterials, nanozymes, and drug-loaded nanosystems developed to repair mitochondrial function and their therapeutic benefits protecting against oxidative stress, restoring cell energy production, preventing cell death, inhibiting protein aggregates, and improving motor and cognitive disability in cellular and animal models of different NI&NDDs.

JM-20 treatment prevents neuronal damage and memory impairment induced by aluminum chloride in rats

The number of people with dementia worldwide is estimated at 50 million by 2018 and continues to rise mainly due to increasing aging and population growth. Clinical impact of current interventions remains modest and all efforts aimed at the identification of new therapeutic approaches are therefore critical. Previously, we showed that JM-20, a dihydropyridine-benzodiazepine hybrid molecule, protected memory processes against scopolamine-induced cholinergic dysfunction. In order to gain further insight into the therapeutic potential of JM-20 on cognitive decline and Alzheimer's disease (AD) pathology, here we evaluated its neuroprotective effects after chronic aluminum chloride (AlCl3) administration to rats and assessed possible alterations in several types of episodic memory and associated pathological mechanisms. Oral administration of aluminum to rodents recapitulates several neuropathological alterations and cognitive impairment, being considered a convenient tool for testing the efficacy of new therapies for dementia. We used behavioral tasks to test spatial, emotional- associative and novel object recognition memory, as well as molecular, enzymatic and histological assays to evaluate selected biochemical parameters. Our study revealed that JM-20 prevented memory decline alongside the inhibition of AlCl3 -induced oxidative stress, increased AChE activity, TNF-α and pro-apoptotic proteins (like Bax, caspase-3, and 8) levels. JM-20 also protected against neuronal damage in the hippocampus and prefrontal cortex. Our findings expanded our understanding of the ability of JM-20 to preserve memory in rats under neurotoxic conditions and confirm its potential capacity to counteract cognitive impairment and etiological factors of AD by breaking the progression of key steps associated with neurodegeneration.

Modified Low-Temperature Extraction Method for Isolation of Bletilla striata Polysaccharide as Antioxidant for the Prevention of Alzheimer's Disease

Amyloid-β (Aβ) peptides play a key role in Alzheimer's disease (AD), the most common type of dementia. In this study, a polysaccharide from Bletilla striata (BSP), with strong antioxidant and anti-inflammatory properties, was extracted using a low-temperature method and tested for its efficacy against AD, in vitro using N2a and BV-2 cells, and in vivo using an AD rat model. The characterization of the extracted BSP for its molecular structure and functional groups demonstrated the effectiveness of the modified method for retaining its bioactivity. In vitro, BSP reduced by 20% reactive oxygen species (ROS) levels in N2a cells (p = 0.0082) and the expression levels of inflammation-related genes by 3-fold TNF-α (p = 0.0048), 4-fold IL-6 (p = 0.0019), and 2.5-fold IL-10 (p = 0.0212) in BV-2 cells treated with Aβ fibrils. In vivo, BSP recovered learning memory, ameliorated morphological damage in the hippocampus and cortex, and reduced the expression of the β-secretase protein in AlCl3-induced AD rats. Collectively, these findings demonstrated the efficacy of BSP for preventing and alleviating the effects of AD.

Toxic Substance-induced Hippocampal Neurodegeneration in Rodents as Model of Alzheimer’s Dementia

BACKGROUND: Alzheimer’s Dementia (AD) cases are increasing with the global elderly population. To study the part of the brain affected by AD, animal models for hippocampal degeneration are still necessary to better understand AD pathogenesis and develop treatment and prevention measures. AIM: This study was a systematic review of toxic substance-induced animal models of AD using the Morris Water Maze method in determining hippocampal-related memory impairment. Our aim was reviewing the methods of AD induction using toxic substances in laboratory rodents and evaluating the report of the AD biomarkers reported in the models. METHODS: Data were obtained from articles in the PubMed database, then compiled, categorized, and analyzed. Eighty studies published in the past 5 years were included for analysis. RESULTS AND DISCUSSION: The most widely used method was intracerebroventricular injection of amyloid-β _substances. However, some less technically challenging techniques using oral or intraperitoneal administration of other toxic substances also produce successful models. Instead of hippocampal neurodegeneration, many studies detected biomarkers of the AD pathological process while some reported inflammation, oxidative stress, neurotrophic factors, and changes of cholinergic activity. Female animals were underrepresented despite a high incidence of AD in women. CONCLUSION: Toxic substances may be used to develop AD animal models characterized with appropriate AD pathological markers. Characterization of methods with the most easy-handling techniques and more studies in female animal models should be encouraged.

Mechanisms Involved in Microglial-Interceded Alzheimer's Disease and Nanocarrier-Based Treatment Approaches

Alzheimer's disease (AD) is a common neurodegenerative disorder accountable for dementia and cognitive dysfunction. The etiology of AD is complex and multifactorial in origin. The formation and deposition of amyloid-beta (Aβ), hyperphosphorylated tau protein, neuroinflammation, persistent oxidative stress, and alteration in signaling pathways have been extensively explored among the various etiological hallmarks. However, more recently, the immunogenic regulation of AD has been identified, and macroglial activation is considered a limiting factor in its etiological cascade. Macroglial activation causes neuroinflammation via modulation of the NLRP3/NF-kB/p38 MAPKs pathway and is also involved in tau pathology via modulation of the GSK-3β/p38 MAPK pathways. Additionally, microglial activation contributes to the discrete release of neurotransmitters and an altered neuronal synaptic plasticity. Therefore, activated microglial cells appear to be an emerging target for managing and treating AD. This review article discussed the pathology of microglial activation in AD and the role of various nanocarrier-based anti-Alzeihmenr's therapeutic approaches that can either reverse or inhibit this activation. Thus, as a targeted drug delivery system, nanocarrier approaches could emerge as a novel means to overcome existing AD therapy limitations.

The influence of vinpocetine alone or in combination with Epigallocatechin-3-gallate, Coenzyme COQ10, Vitamin E and Selenium as a potential neuroprotective combination against aluminium-induced Alzheimer's disease in Wistar Albino Rats

Alzheimer's disease (AD) is one of such diseases that represent the most prominent cause of dementia in elderly people. To explore the possible neuroprotective effect as well as mechanism of action of Vinpocetine either alone or in combination with EGCG, CoQ10, or VE & Se in ameliorating aluminum chloride-induced AD in rats. Rats were received AlCl₃ (70 mg/kg) intraperitoneal daily dose for 30 days along with EGCG (10 mg/kg, I.P), CoQ10 (200 mg/kg, P.O), VE (100 mg/kg, P.O) & Se (1 mg/kg, P.O) as well as Vinpocetine (20 mg/kg, P.O) either alone or in combination. Results revealed that the combination of Vinpocetine with EGCG showed the best neuroprotection. This protection in the brain was indicated by the significant decrease in Aβ and ACHE. The same pattern of results were shown in the levels of monoamines and BDNF. In addition, the combination of Vinpocetine with EGCG showed more pronounced anti-inflammatory (TNF-α, IL-1β) and antioxidant (MDA, SOD, TAC) effects in comparison to other combinations. These results were confirmed using histopathological examinations as well as DNA fragmentation assays. Vinpocetine with EGCG showed pronounced protection on neurons against AD induced by AlCl₃ in rats.

Green Tea Polyphenol Epigallocatechin-Gallate in Amyloid Aggregation and Neurodegenerative Diseases

The accumulation of protein aggregates in human tissues is a hallmark of more than 40 diseases called amyloidoses. In seven of these disorders, the aggregation is associated with neurodegenerative processes in the central nervous system such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD). The aggregation occurs when certain soluble proteins lose their physiological function and become toxic amyloid species. The amyloid assembly consists of protein filament interactions, which can form fibrillar structures rich in β-sheets. Despite the frequent incidence of these diseases among the elderly, the available treatments are limited and at best palliative, and new therapeutic approaches are needed. Among the many natural compounds that have been evaluated for their ability to prevent or delay the amyloidogenic process is epigallocatechin-3-gallate (EGCG), an abundant and potent polyphenolic molecule present in green tea that has extensive biological activity. There is evidence for EGCG’s ability to inhibit the aggregation of α-synuclein, amyloid-β, and huntingtin proteins, respectively associated with PD, AD, and HD. It prevents fibrillogenesis (in vitro and in vivo), reduces amyloid cytotoxicity, and remodels fibrils to form non-toxic amorphous species that lack seed propagation. Although it is an antioxidant, EGCG in an oxidized state can promote fibrils’ remodeling through formation of Schiff bases and crosslinking the fibrils. Moreover, microparticles to drug delivery were synthesized from oxidized EGCG and loaded with a second anti-amyloidogenic molecule, obtaining a synergistic therapeutic effect. Here, we describe several pre-clinical and clinical studies involving EGCG and neurodegenerative diseases and their related mechanisms.

Computational and Experimental Assessments of Magnolol as a Neuroprotective Agent and Utilization of UiO-66(Zr) as Its Drug Delivery System

The phenolic natural product magnolol exhibits neuroprotective properties through β-amyloid toxicity in PC-12 cells and ameliorative effects against cognitive deficits in a TgCRND8 transgenic mice model. Its bioavailability and blood-brain barrier crossing ability have been significantly improved using the metal-organic framework (MOF) UiO-66(Zr) as a drug delivery system (DDS). To investigate the neuroprotective effects of the Zr-based DDS, magnolol and magnolol-loaded-UiO-66(Zr) (Mag@UiO-66(Zr)) were evaluated for inhibitory activity against β-secretase and AlCl₃-induced neurotoxicity. Due to the moderate inhibition observed for magnolol in vitro, in silico binding studies were explored against β-secretase along with 11 enzymes known to affect Alzheimer's disease (AD). Favorable binding energies against CDK2, CKD5, MARK, and phosphodiesterase 3B (PDE3B) and dynamically stable complexes were noted through molecular docking and molecular dynamic simulation experiments, respectively. The magnolol-loaded DDS UiO-66(Zr) also showed enhanced neuroprotective activity against two pathological indices, namely, neutrophil infiltration and apoptotic neurons, in addition to damage reversal compared to magnolol. Thus, MOFs are promising drug delivery platforms for poorly bioavailable drugs.

Taurine and Camel Milk Modulate Neurobehavioral and Biochemical Changes in Aluminum Chloride-Induced Alzheimer's Disease in Rats

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disease associated with deficiency in motor coordination, cognitive impairment, and excessive reactive oxygen species production in the brain.

OBJECTIVE

The study evaluated effects of taurine and camel milk (CM) on neurobehavior, amyloid-beta peptide 1-42 (Aβ) expression, acetylcholinesterase, and superoxide dismutase activities in aluminum chloride (AlCl3) model of Alzheimer's disease in rats.

METHODS

Thirty-five female Wistar rats were divided into seven groups (n = 5): Normal saline (0.2 mL/kg body weight); AlCl3 (100 mg/kg) (AD); CM (33 mL/kg); Taurine (50 mg/kg); AlCl3 (100 mg/kg) + CM (33 mL/kg); AlCl3 (100 mg/kg) + Taurine (50 mg/kg); and AlCl3 (100 mg/kg) + CM (33 mL/kg) + Taurine (50 mg/kg). The administration lasted for eight weeks via oral gavage. After the eighth week, neurobehavior assessments were performed. Rats were sacrificed, and brain and blood samples collected for analysis.

RESULTS

There was a significant (p < 0.0001) increase in the duration of motor endurance in AD + CM rats, compared to AD rats. Duration of forced swimming time was lowest (p < 0.0001) in AlCl3 + Taurine rats, compared to that of AD rats. Concentration of Aβ peptide decreased (p < 0.05) in AD rats, treated with CM and/or combination. In taurine-treated rats, superoxide dismutase activity was significantly (p < 0.05) higher than in AD rats. Treatment with taurine + CM increased (p < 0.05) acetylcholinesterase activity compared to controls.

CONCLUSION

Taurine and CM enhanced cognition and sensorimotor activity by decreasing Aβ peptide concentration and increasing superoxide dismutase and acetylcholinesterase activities in AD rats.

Formaldehyde-Crosslinked Nontoxic Aβ Monomers to Form Toxic Aβ Dimers and Aggregates: Pathogenicity and Therapeutic Perspectives

Alzheimer's disease (AD) is characterized by the presence of senile plaques in the brain. However, medicines targeting amyloid-beta (Aβ) have not achieved the expected clinical effects. This review focuses on the formation mechanism of the Aβ dimer (the basic unit of oligomers and fibrils) and its tremendous potential as a drug target. Recently, age-associated formaldehyde and Aβ-derived formaldehyde have been found to crosslink the nontoxic Aβ monomer to form the toxic dimers, oligomers and fibrils. Particularly, Aβ-induced formaldehyde accumulation and formaldehyde-promoted Aβ aggregation form a vicious cycle. Subsequently, formaldehyde initiates Aβ toxicity in both the early-and late-onset AD. These facts also explain why AD drugs targeting only Aβ do not have the desired therapeutic effects. Development of the nanoparticle-based medicines targeting both formaldehyde and Aβ dimer is a promising strategy for improving the drug efficacy by penetrating blood-brain barrier and extracellular space into the cortical neurons in AD patients.

Optimization of cerebral organoids: a more qualified model for Alzheimer's disease research

Alzheimer's disease (AD) is a neurodegenerative disease that currently cannot be cured by any drug or intervention, due to its complicated pathogenesis. Current animal and cellular models of AD are unable to meet research needs for AD. However, recent three-dimensional (3D) cerebral organoid models derived from human stem cells have provided a new tool to study molecular mechanisms and pharmaceutical developments of AD. In this review, we discuss the advantages and key limitations of the AD cerebral organoid system in comparison to the commonly used AD models, and propose possible solutions, in order to improve their application in AD research. Ethical concerns associated with human cerebral organoids are also discussed. We also summarize future directions of studies that will improve the cerebral organoid system to better model the pathological events observed in AD brains.

[Constructing Brain Aβ-Targeting Nanoparticles Loaded with EGCG for Treating Alzheimer's Disease in Mice]

OBJECTIVE

To construct a nanodelivery system surface-modified with RD2 peptide (polypeptide sequence PTLHTHNRRRRR) for brain tissue penetration and β-amyloid (Aβ) binding. Epigallocatechin-3-gallate (EGCG) was selected for encapsulation in the targeted delivery system and its therapeutic potential for Alzheimer's disease (AD) was investigated.

METHODS

EGCG-load nanoparticles (NP/EGCG), NP/EGCG with RD2 peptide surface modification (RD2-NP/EGCG), as well as RD2 peptide-modified blank nanoparticles (RD2-NP) were prepared and characterized. Thioflavin T assay was done to assess the ability of RD2-NP to bind with Aβ and ex vivo imaging was conducted to evaluate the distribution of RD2-NP in brain lesion sites. The AD mice model was established by injecting oligomeric Aβ 42 in the bilateral hippocampi of ICR mice. Then AD mice were administered intravenously through the tail vein with normal saline, EGCG solution, NP/EGCG or RD2-NP/EGCG for 28 d, respectively, and the Morris water maze tests were performed to assess the spatial memory of mice. Subsequently, RT-PCR method was used to determine the mRNA levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the hippocampus of the mice, and the morphological changes of hippocampal neurons were observed with Nissl staining. Additionally, the pathological changes of heart, liver, spleen, lung, and kidney were characterized by hematoxylin-eosin (HE) staining.

RESULTS

The particle diameter of the prepared RD2-NP/EGCG was (204.83±2.80) nm and the zeta potential was -23.88 mV. The encapsulation efficiency and drug loading capacity were 94.39% and 5.90%, respectively. The RD2 peptide modification has no significant effect on the physiochemical properties of the nanoparticles. RD2-NP had good Aβ binding ability, and it could be concentrated in hippocampus and cerebral cortex, the most common Aβ deposition sites. The four-week RD2-NP/EGCG treatment significantly decreased the expression of the pro-inflammatory cytokine TNF-α and IL-1β, restored neuronal losses and hippocampal damage, and ameliorated spatial memory impairment in AD model mice. Moreover, treatment with the RD2-NP/EGCG did not present organ toxicity.

CONCLUSION

Surface modified RD2 peptide nanodelivery system can efficiently deliver drugs to AD lesions and improve the therapeutic effect of EGCG on AD.