Ability of selenium species to inhibit metal-induced Aβ aggregation involved in the development of Alzheimer’s disease

The Role of Gut Microbiota in the Neuroprotective Effects of Selenium in Alzheimer's Disease

The objective of the present review was to provide a timely update on the molecular mechanisms underlying the beneficial role of Se in Alzheimer's disease pathogenesis, and discuss the potential role of gut microbiota modulation in this neuroprotective effect. The existing data demonstrate that selenoproteins P, M, S, R, as well as glutathione peroxidases and thioredoxin reductases are involved in regulation of Aβ formation and aggregation, tau phosphorylation and neurofibrillary tangles formation, as well as mitigate the neurotoxic effects of Aβ and phospho-tau. Correspondingly, supplementation with various forms of Se in cellular and animal models of AD was shown to reduce Aβ formation, tau phosphorylation, reverse the decline in brain antioxidant levels, inhibit neuronal oxidative stress and proinflammatory cytokine production, improve synaptic plasticity and neurogenesis, altogether resulting in improved cognitive functions. In addition, most recent findings demonstrate that these neuroprotective effects are associated with Se-induced modulation of gut microbiota. In animal models of AD, Se supplementation was shown to improve gut microbiota biodiversity with a trend to increased relative abundance of Lactobacillus, Bifidobacterium, and Desulfivibrio, while reducing that of Lachnospiracea_NK4A136, Rikenella, and Helicobacter. Moreover, the relative abundance of Se-affected taxa was significantly associated with Aβ accumulation, tau phosphorylation, neuronal oxidative stress, and neuroinflammation, indicative of the potential role of gut microbiota to mediate the neuroprotective effects of Se in AD. Hypothetically, modulation of gut microbiota along with Se supplementation may improve the efficiency of the latter in AD, although further detailed laboratory and clinical studies are required.

Selenium Nanoparticles as Neuroprotective Agents: Insights into Molecular Mechanisms for Parkinson's Disease Treatment

Oxidative stress and the accumulation of misfolded proteins in the brain are the main causes of Parkinson's disease (PD). Several nanoparticles have been used as therapeutics for PD. Despite their therapeutic potential, these nanoparticles induce multiple stresses upon entry. Selenium (Se), an essential nutrient in the human body, helps in DNA formation, stress control, and cell protection from damage and infections. It can also regulate thyroid hormone metabolism, reduce brain damage, boost immunity, and promote reproductive health. Selenium nanoparticles (Se-NPs), a bioactive substance, have been employed as treatments in several disciplines, particularly as antioxidants. Se-NP, whether functionalized or not, can protect mitochondria by enhancing levels of reactive oxygen species (ROS) scavenging enzymes in the brain. They can also promote dopamine synthesis. By inhibiting the aggregation of tau, α-synuclein, and/or Aβ, they can reduce the cellular toxicities. The ability of the blood-brain barrier to absorb Se-NPs which maintain a healthy microenvironment is essential for brain homeostasis. This review focuses on stress-induced neurodegeneration and its critical control using Se-NP. Due to its ability to inhibit cellular stress and the pathophysiologies of PD, Se-NP is a promising neuroprotector with its anti-inflammatory, non-toxic, and antimicrobial properties.

The Promising Role of Selenium and Yeast in the Fight Against Protein Amyloidosis

In recent years, increasing attention has been paid to research on diseases related to the deposition of misfolded proteins (amyloids) in various organs. Moreover, modern scientists emphasise the importance of selenium as a bioelement necessary for the proper functioning of living organisms. The inorganic form of selenium-sodium selenite (redox-active)-can prevent the formation of an insoluble polymer in proteins. It is very important to undertake tasks aimed at understanding the mechanisms of action of this element in inhibiting the formation of various types of amyloid. Furthermore, yeast cells play an important role in this matter as a eukaryotic model organism, which is intensively used in molecular research on protein amyloidosis. Due to the lack of appropriate treatment in the general population, the problem of amyloidosis remains unsolved. This extracellular accumulation of amyloid is one of the main factors responsible for the occurrence of Alzheimer's disease. The review presented here contains scientific information discussing a brief description of the possibility of amyloid formation in cells and the use of selenium as a factor preventing the formation of these protein aggregates. Recent studies have shown that the yeast model can be successfully used as a eukaryotic organism in biotechnological research aimed at understanding the essence of the entire amyloidosis process. Understanding the mechanisms that regulate the reaction of yeast to selenium and the phenomenon of amyloidosis is important in the aetiology and pathogenesis of various disease states. Therefore, it is imperative to conduct further research and analysis aimed at explaining and confirming the role of selenium in the processes of protein misfolding disorders. The rest of the article discusses the characteristics of food protein amyloidosis and their use in the food industry. During such tests, their toxicity is checked because not all food proteins can produce amyloid that is toxic to cells. It should also be noted that a moderate diet is beneficial for the corresponding disease relief caused by amyloidosis.

A Simple Sandwich Electrochemical Immunosensor for Rapid Detection of the Alzheimer's Disease Biomarker Tau Protein

As a typical biomarker of Alzheimer's disease, rapid and specific detection of tau protein can help improve the early diagnosis and prognosis of the disease. In this study, a simple sandwich electrochemical immunosensor was developed for rapid detection of tau protein. Primary monoclonal antibodies (mAb1) against the middle domain of tau protein (amino acids 189-195) were immobilized on the gold electrode surface through a self-assembled monolayer (SAM) of 3,3'-dithiobis (sulfosuccinimidyl propionate) (DTSSP). Then the tau protein was captured through the specific adsorption between the antigen and the antibody, resulting in a change in the impedance. Secondary monoclonal antibodies (mAb2) against the N-terminal region of tau protein were used for further amplification of the binding reaction between mAb1 and tau protein. A linear correlation between the total change in impedance and the logarithm of tau concentration was found from 2 × 10-6 mg mL-1 to 2 × 10-3 mg mL-1, with a detection limit as low as 1 × 10-6 mg mL-1. No significant interference was observed from human serum albumin. Furthermore, the fabricated sandwich immunosensor successfully detected target tau protein in artificial cerebrospinal fluid (aCSF) samples, indicating good potential for clinical applications in the future.

Multifunctional Nanocarriers for Alzheimer's Disease: Befriending the Barriers

Neurodegenerative diseases (NDDs) have been increasing in incidence in recent years and are now widespread worldwide. Neuronal death is defined as the progressive loss of neuronal structure or function which is closely associated with NDDs and represents the intrinsic features of such disorders. Amyotrophic lateral sclerosis, frontotemporal dementia, Alzheimer's, Parkinson's, and Huntington's diseases (AD, PD, and HD, respectively) are considered neurodegenerative diseases that affect a large number of people worldwide. Despite the testing of various drugs, there is currently no available therapy that can remedy or effectively slow the progression of these diseases. Nanomedicine has the potential to revolutionize drug delivery for the management of NDDs. The use of nanoparticles (NPs) has recently been developed to improve drug delivery efficiency and is currently subjected to extensive studies. Nanoengineered particles, known as nanodrugs, can cross the blood-brain barrier while also being less invasive compared to the most treatment strategies in use. Polymeric, magnetic, carbonic, and inorganic NPs are examples of NPs that have been developed to improve drug delivery efficiency. Primary research studies using NPs to cure AD are promising, but thorough research is needed to introduce these approaches to clinical use. In the present review, we discussed the role of metal-based NPs, polymeric nanogels, nanocarrier systems such as liposomes, solid lipid NPs, polymeric NPs, exosomes, quantum dots, dendrimers, polymersomes, carbon nanotubes, and nanofibers and surfactant-based systems for the therapy of neurodegenerative diseases. In addition, we highlighted nanoformulations such as N-butyl cyanoacrylate, poly(butyl cyanoacrylate), D-penicillamine, citrate-coated peptide, magnetic iron oxide, chitosan (CS), lipoprotein, ceria, silica, metallic nanoparticles, cholinesterase inhibitors, an acetylcholinesterase inhibitors, metal chelators, anti-amyloid, protein, and peptide-loaded NPs for the treatment of AD.

Unravelling the in vitro and in vivo potential of selenium nanoparticles in Alzheimer's disease: A bioanalytical review

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by progressive cognitive decline and the accumulation of beta-amyloid plaques and tau tangles in the brain. Current therapies have limited efficacy, prompting the search for novel treatments. Selenium nanoparticles (SeNPs) have emerged as promising candidates for AD therapy due to their unique physicochemical properties and potential therapeutic effects. This review provides an overview of SeNPs and their potential application in AD treatment, as well as the main bioanalytical techniques applied in this field. SeNPs possess antioxidant and anti-inflammatory properties, making them potential candidates to combat the oxidative stress and neuroinflammation associated with AD. Moreover, SeNPs have shown the ability to cross the blood-brain barrier (BBB), allowing them to target brain regions affected by AD pathology. Various methods for synthesizing SeNPs are explored, including chemical, physical and biological synthesis approaches. Based on the employment of algae, yeast, fungi, and plants, green methods offer a promising and biocompatible alternative for SeNPs production. In vitro studies have demonstrated the potential of SeNPs in reducing beta-amyloid aggregation and inhibiting tau hyperphosphorylation, providing evidence of their neuroprotective effects on neuronal cells. In vivo studies using transgenic mouse models and AD-induced symptoms have shown promising results, with SeNPs treatment leading to cognitive improvements and reduced amyloid plaque burden in the hippocampus. Looking ahead, future trends in SeNPs research involve developing innovative brain delivery strategies to enhance their therapeutic potential, exploring alternative animal models to complement traditional mouse studies, and investigating multi-targeted SeNPs formulations to address multiple aspects of AD pathology. Overall, SeNPs represent a promising avenue for AD treatment, and further research in this field may pave the way for effective and much-needed therapeutic interventions for individuals affected by this debilitating disease.

The Potential of Plum Seed Residue: Unraveling the Effect of Processing on Phytochemical Composition and Bioactive Properties

Bioactive compounds extracted from plum seeds were identified and quantified, aiming to establish how the brandy manufacturing process affects the properties and possible cascade valorization of seed residues. Extraction with n-hexane using Soxhlet has provided oils rich in unsaturated fatty acids (92.24-92.51%), mainly oleic acid (72-75.56%), which is characterized by its heart-healthy properties. The fat extracts also contain tocopherols with antioxidant and anti-inflammatory properties. All the ethanol-water extracts of the defatted seeds contain neochlorogenic acid (90-368 µg·g-1), chlorogenic acid (36.1-117 µg·g-1), and protocatechuate (31.8-100 µg·g-1) that have an impact on bioactive properties such as antimicrobial and antioxidant. Anti-amyloidogenic activity (25 mg·mL-1) was observed in the after both fermentation and distillation extract, which may be related to high levels of caffeic acid (64 ± 10 µg·g-1). The principal component analysis showed that all plum seed oils could have potential applications in the food industry as edible oils or in the cosmetic industry as an active ingredient in anti-aging and anti-stain cosmetics, among others. Furthermore, defatted seeds, after both fermentation and distillation, showed the greatest applicability in the food and nutraceutical industry as a food supplement or as an additive in the design of active packaging.

The Role of Micronutrients in Neurological Disorders

Trace elements and vitamins, collectively known as micronutrients, are essential for basic metabolic reactions in the human body. Their deficiency or, on the contrary, an increased amount can lead to serious disorders. Research in recent years has shown that long-term abnormal levels of micronutrients may be involved in the etiopathogenesis of some neurological diseases. Acute and chronic alterations in micronutrient levels may cause other serious complications in neurological diseases. Our aim was to summarize the knowledge about micronutrients in relation to selected neurological diseases and comment on their importance and the possibilities of therapeutic intervention in clinical practice.

Cytotoxicity, uptake and accumulation of selenium nanoparticles and other selenium species in neuroblastoma cell lines related to Alzheimer's disease by using cytotoxicity assays, TEM and single cell-ICP-MS

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease, representing 80% of the total dementia cases. The "amyloid cascade hypothesis" stablishes that the aggregation of the beta-amyloid protein (Aβ₄₂) is the first event that subsequently triggers AD development. Selenium nanoparticles stabilized with chitosan (Ch-SeNPs) have demonstrated excellent anti-amyloidogenic properties in previous works, leading to an improvement of AD aetiology. Here, the in vitro effect of selenium species in AD model cell line has been study to obtain a better assessment of their effects in AD treatment. For this purpose, mouse neuroblastoma (Neuro-2a) and human neuroblastoma (SH-SY5Y) cell lines were used. Cytotoxicity of selenium species, such as selenomethionine (SeMet), Se-methylselenocysteine (MeSeCys) and Ch-SeNPs, has been determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry methods. Intracellular localisation of Ch-SeNPs, and their pathway through SH-SY5Y cell line, have been evaluated by transmission electron microscopy (TEM). The uptake and accumulation of selenium species by both neuroblastoma cell lines have been quantified at single cell level by single cell- Inductively Coupled Plasma with Mass Spectrometry detection (SC-ICP-MS), with a previous optimisation of transport efficiency using gold nanoparticles (AuNPs) ((69 ± 3) %) and 2.5 mm calibration beads ((92 ± 8) %). Results showed that Ch-SeNPs would be more readily accumulated by both cell lines than organic species being accumulation ranges between 1.2 and 89.5 fg Se cell^-1 for Neuro-2a and 3.1-129.8 fg Se cell^-1 for SH-SY5Y exposed to 250 μM Ch-SeNPs. Data obtained were statistically treated using chemometric tools. These results provide an important insight into the interaction of Ch-SeNPs with neuronal cells, which could support their potential use in AD treatment.

Revisiting the Role of Vitamins and Minerals in Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of dementia that affects millions of individuals worldwide. It is an irreversible neurodegenerative disorder that is characterized by memory loss, impaired learning and thinking, and difficulty in performing regular daily activities. Despite nearly two decades of collective efforts to develop novel medications that can prevent or halt the disease progression, we remain faced with only a few options with limited effectiveness. There has been a recent growth of interest in the role of nutrition in brain health as we begin to gain a better understanding of what and how nutrients affect hormonal and neural actions that not only can lead to typical cardiovascular or metabolic diseases but also an array of neurological and psychiatric disorders. Vitamins and minerals, also known as micronutrients, are elements that are indispensable for functions including nutrient metabolism, immune surveillance, cell development, neurotransmission, and antioxidant and anti-inflammatory properties. In this review, we provide an overview on some of the most common vitamins and minerals and discuss what current studies have revealed on the link between these essential micronutrients and cognitive performance or AD.

Latent Potential of Multifunctional Selenium Nanoparticles in Neurological Diseases and Altered Gut Microbiota

Neurological diseases remain a major concern due to the high world mortality rate and the absence of appropriate therapies to cross the blood-brain barrier (BBB). Therefore, the major focus is on the development of such strategies that not only enhance the efficacy of drugs but also increase their permeability in the BBB. Currently, nano-scale materials seem to be an appropriate approach to treating neurological diseases based on their drug-loading capacity, reduced toxicity, targeted delivery, and enhanced therapeutic effect. Selenium (Se) is an essential micronutrient and has been of remarkable interest owing to its essential role in the physiological activity of the nervous system, i.e., signal transmission, memory, coordination, and locomotor activity. A deficiency of Se leads to various neurological diseases such as Parkinson's disease, epilepsy, and Alzheimer's disease. Therefore, owing to the neuroprotective role of Se (selenium) nanoparticles (SeNPs) are of particular interest to treat neurological diseases. To date, many studies investigate the role of altered microbiota with neurological diseases; thus, the current review focused not only on the recent advancement in the field of nanotechnology, considering SeNPs to cure neurological diseases, but also on investigating the potential role of SeNPs in altered microbiota.

Engineering a thermostable biosensor based on biomimetic mineralization HRP@Fe-MOF for Alzheimer's disease

The development of disease detection by biosensors represents one of the key components of medical science. However, millions of people are still misdiagnosed each year due to the poor efficacy and thermal instability of biosensors. Using horseradish peroxidase (HRP) as a paradigm, we offer a rational design strategy to optimize the thermostability and activity of biosensors by biomimetic mineralization. To overcome the weak thermostability of the biosensor, the mineralization of Fe-MOF forms an armor on HRP that protects against high temperature. Additionally, the biomimetic mineralization HRP@Fe-MOF can double-catalyze the TMB/H₂O₂ chromogenic system for color development. The biosensor can also be recycled through simple heat treatment due to the thermally stable aptamer and biomimetic mineralization HRP@Fe-MOF. The optical biosensor based on this sensitive spectral transformation was successfully developed for the measurement of AβO with an outstanding linear range (0.0001-10 nM) and a low limit of detection (LOD) of 0.03 pM. This promising platform will open up new avenues for the detection of AβO in the early diagnosis of Alzheimer's disease (AD).

Seleno-Metabolites and Their Precursors: A New Dawn for Several Illnesses?

Selenium (Se) is an essential element for human health as it is involved in different physiological functions. Moreover, a great number of Se compounds can be considered potential agents in the prevention and treatment of some diseases. It is widely recognized that Se activity is related to multiple factors, such as its chemical form, dose, and its metabolism. The understanding of its complex biochemistry is necessary as it has been demonstrated that the metabolites of the Se molecules used to be the ones that exert the biological activity. Therefore, the aim of this review is to summarize the recent information about its most remarkable metabolites of acknowledged biological effects: hydrogen selenide (HSe-/H2Se) and methylselenol (CH3SeH). In addition, special attention is paid to the main seleno-containing precursors of these derivatives and their role in different pathologies.

Neuroprotective activity of selenium nanoparticles against the effect of amino acid enantiomers in Alzheimer's disease

Alzheimer's disease (AD), the most prevalent neurodegenerative disease, is characterized by extracellular accumulation of amyloid-beta protein (Aβ), which is believed to be the very starting event of AD neurodegeneration. In this work, D-Phe, D-Ala, and D-Glu amino acids, which are the non-occurring enantiomeric form in the human body, and also D-Asp and DL-SeMet, have proved to be amyloidogenic regarding Aβ₄₂ aggregation in TEM studies. These amyloidogenic amino acid enantiomers also widened Aβ₄₂ fibrils up to 437% regarding Aβ₄₂ alone, suggesting that Aβ₄₂ aggregation is enantiomerically dependent. To inhibit enantiomeric-induced amyloid aggregation, selenium nanoparticles stabilized with chitosan (Ch-SeNPs) were successfully synthesized and employed. Thus, Ch-SeNPs reduced and even completely inhibited Aβ₄₂ aggregation produced in the presence of some amino acid enantiomers. In addition, through UV-Vis spectroscopy and fluorescence studies, it was deduced that Ch-SeNPs were able to interact differently with amino acids depending on their enantiomeric form. On the other hand, antioxidant properties of amino acid enantiomers were evaluated by DPPH and TBARS assays, with Tyr enantiomers being the only ones showing antioxidant effect. All spectroscopic data were statistically analysed through experimental design and response surface analysis, showing that the interaction between the Ch-SeNPs and the amino acids studied was enantioselective and allowing, in some cases, to establish the concentration ratios in which this interaction is maximum.

Role of micronutrients in Alzheimer's disease: Review of available evidence

Alzheimer's disease (AD) is one of the most common age-related neurodegenerative disorders that have been studied for more than 100 years. Although an increased level of amyloid precursor protein is considered a key contributor to the development of AD, the exact pathogenic mechanism remains known. Multiple factors are related to AD, such as genetic factors, aging, lifestyle, and nutrients. Both epidemiological and clinical evidence has shown that the levels of micronutrients, such as copper, zinc, and iron, are closely related to the development of AD. In this review, we summarize the roles of eight micronutrients, including copper, zinc, iron, selenium, silicon, manganese, arsenic, and vitamin D in AD based on recently published studies.

Neuroprotective mechanisms of multitarget 7-aminophenanthridin-6(5H)-one derivatives against metal-induced amyloid proteins generation and aggregation

Brain's metals accumulation is associated with toxic proteins, like amyloid-proteins (Aβ), formation, accumulation, and aggregation, leading to neurodegeneration. Metals downregulate the correct folding, disaggregation, or degradation mechanisms of toxic proteins, as heat shock proteins (HSPs) and proteasome. The 7-amino-phenanthridin-6(5H)-one derivatives (APH) showed neuroprotective effects against metal-induced cell death through their antioxidant effect, independently of their chelating activity. However, additional neuroprotective mechanisms seem to be involved. We tested the most promising APH compounds (APH1-5, 10-100 μM) chemical ability to prevent metal-induced Aβ proteins aggregation; the APH1-5 effect on HSP70 and proteasome 20S (P20S) expression, the metals effect on Aβ formation and the involvement of HSP70 and P20S in the process, and the APH1-5 neuroprotective effects against Aβ proteins (1 μM) and metals in SN56 cells. Our results show that APH1-5 compounds chemically avoid metal-induced Aβ proteins aggregation and induce HSP70 and P20S expression. Additionally, iron and cadmium induced Aβ proteins formation through downregulation of HSP70 and P20S. Finally, APH1-5 compounds protected against Aβ proteins-induced neuronal cell death, reversing partially or completely this effect. These data may help to provide a new therapeutic approach against the neurotoxic effect induced by metals and other environmental pollutants, especially when mediated by toxic proteins.

Novel Rivastigmine Derivatives as Promising Multi-Target Compounds for Potential Treatment of Alzheimer’s Disease

Alzheimer’s disease (AD) is the most serious and prevalent neurodegenerative disorder still without cure. Since its aetiology is diverse, recent research on anti-AD drugs has been focused on multi-target compounds. In this work, seven novel hybrids (RIV–BIM) conjugating the active moiety of the drug rivastigmine (RIV) with 2 isomeric hydroxyphenylbenzimidazole (BIM) units were developed and studied. While RIV assures the inhibition of cholinesterases, BIM provides further appropriate properties, such as inhibition of amyloid β-peptide (Aβ) aggregation, antioxidation and metal chelation. The evaluated biological properties of these hybrids included antioxidant activity; inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and Aβ₄₂ aggregation; as well as promotion of cell viability and neuroprotection. All the compounds are better inhibitors of AChE than rivastigmine (IC₅₀ = 32.1 µM), but compounds of series 5 are better inhibitors of BChE (IC₅₀ = 0.9−1.7 µM) than those of series 4. Series 5 also showed good capacity to inhibit self- (42.1−58.7%) and Cu(II)-induced (40.3−60.8%) Aβ aggregation and also to narrow (22.4−42.6%) amyloid fibrils, the relevant compounds being 5b and 5d. Some of these compounds can also prevent the toxicity induced in SH-SY5Y cells by Aβ₄₂ and oxidative stress. Therefore, RIV–BIM hybrids seem to be potential drug candidates for AD with multi-target abilities.

Alzheimer's Disease Association with Metals and Metalloids Concentration in Blood and Urine

As there is some evidence that the risk for Alzheimer’s disease (AD) is partially attributable to environmental exposure to some metals and metalloids, we examined an association between AD and arsenic, chromium, and selenium in 53 AD patients and 217 controls. Urinary arsenic, blood chromium, and selenium were determined by inductively coupled plasma mass spectrometry. Logistic regression models calculating odds ratios (ORs) and 95% confidence intervals (CI) were used to estimate AD association with arsenic, chromium, and selenium. In AD patients, urinary arsenic and blood chromium were significantly higher, while blood selenium was significantly lower compared to controls. Increased blood selenium was related to a significant decrease in the odds of AD after adjustment for risk factors. Blood selenium per 1 kg × 10⁻⁹/m³ × 10⁻⁴ increment was associated with 1.4 times lower risk of AD (OR = 0.71; 95% CI 0.58–0.87). A significant increase in the odds of AD associated with increased blood chromium was also seen in the adjusted model: the OR per 1 kg × 10⁻⁹/m³ × 10⁻³ chromium increment was 2.39 (95% CI 1.32–4.31). The association of urinary arsenic with the risk of AD was not significant. The data obtained provide evidence that selenium reduces the risk of Alzheimer’s disease, while chromium increases it.

Silymarin-Encapsulated Xanthan Gum-Stabilized Selenium Nanocarriers for Enhanced Activity Against Amyloid Fibril Cytotoxicity

The accumulation of amyloid-beta at the neuronal sites is a major pathological hallmark involved in the etiology of Alzheimer's disease. To reduce the Aβ-induced neuronal cytotoxicity, selenium nanoparticles and silymarin were fabricated in a single polysaccharide matrix for dual antioxidant and Aβ fibril disaggregation activity. These nanoparticles were further stabilized by an exopolysaccharide xanthan gum. The nanoparticles were fabricated to reduce the amyloid-induced cytotoxicity in SH-SY5Y cells. A three-step method employing redox reaction of sodium selenite and ascorbic acid has been adopted for the synthesis of selenium nanoparticles. Consequently, xanthan gum powder was added to impart stability to the nanocarriers. The nanoparticles exhibited a particle size of 119.2 ± 2.8 nm, zeta potential of - 35.4 ± 3.8 mV, and % EE of 87.7 ± 2.23. HR-TEM with EDX analysis confirmed the presence of spherical nanoparticles. An in vitro drug release study exhibited 89.33 ± 5.4% release of silymarin from nanocarriers and was able to scavenge 90% free radicals of DPPH reagent. The thioflavin T (ThT) fibrillation kinetics study showed that the nanoparticles elicited maximum disaggregation of Aβ fibrils that was depicted by the quenched fluorescence intensity signal. The cell viability results revealed that the highest neuroprotection activity was observed in the cell group treated with SLY-XG-Se against Aβ _1-42-induced toxicity. The nanoparticles were able to internalize in SH-SY5Y cells. Our findings showed that the nanocarrier elicited anti-aggregation efficacy in neuronal cell lines and mitigated the Aβ-induced cytotoxicity, which represents the prospects of neuroprotection involved in the therapeutics of AD.

Anti-Amyloidogenic and Fibril-Disaggregating Potency of the Levodopa-Functionalized Gold Nanoroses as Exemplified in a Diphenylalanine-Based Amyloid Model

The phenomenon of proteins/peptide assembly into amyloid fibrils is associated with various neurodegenerative and age-related human disorders. Inhibition of the aggregation behavior of amyloidogenic peptides/proteins or disruption of the pre-formed aggregates is a viable therapeutic option to control the progression of various protein aggregation-related disorders such as Alzheimer's disease (AD). In the current work, we investigated both the amyloid inhibition and disaggregation proclivity of levodopa-functionalized gold nanoroses (GNRs) against various peptide-based amyloid models, including the amyloid beta peptide [Aβ (1-42) and Aβ (1-40)] and the dipeptide phenylalanine-phenylalanine (FF). Our results depicted the anti-aggregation behavior of the GNR toward FF and both forms of Aβ-derived fibrils. The peptides demonstrated a variation in their fiber-like morphology and a decline in thioflavin T fluorescence after being co-incubated with the GNR. We further demonstrated the neuroprotective effects of the GNR in neuroblastoma cells against FF and Aβ (1-42) fiber-induced toxicity, exemplified both in terms of regaining cellular viability and reducing production of reactive oxygen species. Overall, these findings support the potency of the GNR as a promising platform for combating AD.

The Role of Selenium in Pathologies: An Updated Review

Selenium is an essential microelement required for a number of biological functions. Selenium—and more specifically the amino acid selenocysteine—is present in at least 25 human selenoproteins involved in a wide variety of essential biological functions, ranging from the regulation of reactive oxygen species (ROS) concentration to the biosynthesis of hormones. These processes also play a central role in preventing and modulating the clinical outcome of several diseases, including cancer, diabetes, Alzheimer’s disease, mental disorders, cardiovascular disorders, fertility impairments, inflammation, and infections (including SARS-CoV-2). Over the past years, a number of studies focusing on the relationship between selenium and such pathologies have been reported. Generally, an adequate selenium nutritional state—and in some cases selenium supplementation—have been related to improved prognostic outcome and reduced risk of developing several diseases. On the other hand, supra-nutritional levels might have adverse effects. The results of recent studies focusing on these topics are summarized and discussed in this review, with particular emphasis on advances achieved in the last decade.

Novel strategies for the fight of Alzheimer's disease targeting amyloid-β protein

Alzheimer's disease (AD), which is recognised as a devastating neurodegenerative disease throughout the world and lack of effective treatments, is a growing concern in modern society with a growing population of elderly patients. A growing number of studies reveal that abnormal accumulation and deposition of Aβ is responsible for AD. Inspired by this, strategies for the treatment of AD targeting-Aβ clearance have been discussed for a long period, exploring new drugs which is capable of destroying soluble Aβ oligomers and unsolvable Aβ aggregates. In this paper, results of recent clinical trials on several anti-amyloid-β drugs are presented and several emerging anti-amyloid AD therapies based on recent studies are reviewed. Furthermore, some of the current challenges and novel strategies to prevent AD are addressed. Herein, this review focuses on current pharmacotherapy of AD targeting-Aβ and intends to design a promising therapeutic agent for AD treatment.

Copper, Iron, Selenium and Lipo-Glycemic Dysmetabolism in Alzheimer's Disease

The aim of the present review is to discuss traditional hypotheses on the etiopathogenesis of Alzheimer's disease (AD), as well as the role of metabolic-syndrome-related mechanisms in AD development with a special focus on advanced glycation end-products (AGEs) and their role in metal-induced neurodegeneration in AD. Persistent hyperglycemia along with oxidative stress results in increased protein glycation and formation of AGEs. The latter were shown to possess a wide spectrum of neurotoxic effects including increased Aβ generation and aggregation. In addition, AGE binding to receptor for AGE (RAGE) induces a variety of pathways contributing to neuroinflammation. The existing data also demonstrate that AGE toxicity seems to mediate the involvement of copper (Cu) and potentially other metals in AD pathogenesis. Specifically, Cu promotes AGE formation, AGE-Aβ cross-linking and up-regulation of RAGE expression. Moreover, Aβ glycation was shown to increase prooxidant effects of Cu through Fenton chemistry. Given the role of AGE and RAGE, as well as metal toxicity in AD pathogenesis, it is proposed that metal chelation and/or incretins may slow down oxidative damage. In addition, selenium (Se) compounds seem to attenuate the intracellular toxicity of the deranged tau and Aβ, as well as inhibiting AGE accumulation and metal-induced neurotoxicity.

Selenium Nanoparticles for Biomedical Applications: From Development and Characterization to Therapeutics

Selenium (Se) is an essential element to human health that can be obtained in nature through several sources. In the human body, it is incorporated into selenocysteine, an amino acid used to synthesize several selenoproteins, which have an active center usually dependent on the presence of Se. Although Se shows several beneficial properties in human health, it has also a narrow therapeutic window, and therefore the excessive intake of inorganic and organic Se-based compounds often leads to toxicity. Nanoparticles based on Se (SeNPs) are less toxic than inorganic and organic Se. They are both biocompatible and capable of effectively delivering combinations of payloads to specific cells following their functionalization with active targeting ligands. Herein, the main origin of Se intake, its role on the human body, and its primary biomedical applications are revised. Particular focus will be given to the main therapeutic targets that are explored for SeNPs in cancer therapies, discussing the different functionalization methodologies used to improve SeNPs stability, while enabling the extensive delivery of drug-loaded SeNP to tumor sites, thus avoiding off-target effects.

Potential Role of Nanoparticles in Treating the Accumulation of Amyloid-Beta Peptide in Alzheimer's Patients

The disorder of Alzheimer's is marked by progressive pathophysiological neurodegeneration. The amino acid peptides in the amyloid plaques found in the brains of people with Alzheimer's disease (AD) are known as amyloid-beta (Aβ). Current treatments are not curative, and the effects associated with AD are reduced. Improving treatment results involved the targeting of drugs at optimum therapeutic concentration. Nanotechnology is seen as an unconventional, modern technology that plays a key role in the treatment of Alzheimer's disease. Using nanoparticles, molecular detection, effective drug targeting, and their combination offer high sensitivity. The aim of this review is to shed light on the function and successful role of nanoparticles to resolve Aβ aggregation and thus to help cure Alzheimer's disease. The analysis divides these nanoparticles into three categories: polymer, lipid, and gold nanoparticles. A thorough comparison was then made between the nanoparticles, which are used according to their role, properties, and size in the procedure. The nanoparticles can prevent the accumulation of Aβ during the efficient delivery of the drug to the cells to treat Alzheimer's disease. Furthermore, this comparison demonstrated the ability of these nanoparticles to deal efficiently with Alzheimer's disease. The role of these nanoparticles varied from delivering the drug to brain cells to dealing with the disease-causing peptide.