The novel multitarget iron chelating and propargylamine drug M30 affects APP regulation and processing activities in Alzheimer's disease models

Ferroptosis: A new strategy for targeting Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a complex pathogenesis, which involves the formation of amyloid plaques and neurofibrillary tangles. Many recent studies have revealed a close association between ferroptosis and the pathogenesis of AD. Factors such as ferroptosis-associated iron overload, lipid peroxidation, disturbances in redox homeostasis, and accumulation of reactive oxygen species have been found to contribute to the pathological progression of AD. In this review, we explore the mechanisms underlying ferroptosis, describe the link between ferroptosis and AD, and examine the reported efficacy of ferroptosis inhibitors in treating AD. Finally, we discuss the potential challenges to ferroptosis inhibitors use in the clinic, enabling their faster use in clinical treatment.

The Role of Oxygen Homeostasis and the HIF-1 Factor in the Development of Neurodegeneration

Understanding the molecular underpinnings of neurodegeneration processes is a pressing challenge for medicine and neurobiology. Alzheimer's disease (AD) and Parkinson's disease (PD) represent the most prevalent forms of neurodegeneration. To date, a substantial body of experimental evidence has strongly implicated hypoxia in the pathogenesis of numerous neurological disorders, including AD, PD, and other age-related neurodegenerative conditions. Hypoxia-inducible factor (HIF) is a transcription factor that triggers a cell survival program in conditions of oxygen deprivation. The involvement of HIF-1α in neurodegenerative processes presents a complex and sometimes contradictory picture. This review aims to elucidate the current understanding of the interplay between hypoxia and the development of AD and PD, assess the involvement of HIF-1 in their pathogenesis, and summarize promising therapeutic approaches centered on modulating the activity of the HIF-1 complex.

Ferroptosis-Regulated Cell Death as a Therapeutic Strategy for Neurodegenerative Diseases: Current Status and Future Prospects

Ferroptosis is increasingly being recognized as a key element in the pathogenesis of diverse diseases. Recent studies have highlighted the intricate links between iron metabolism and neurodegenerative disorders. Emerging evidence suggests that iron homeostasis, oxidative stress, and neuroinflammation all contribute to the regulation of both ferroptosis and neuronal health. However, the precise molecular mechanisms underlying the involvement of ferroptosis in the pathological processes of neurodegeneration and its impact on neuronal dysfunction remain incompletely understood. In our Review, we provide a comprehensive analysis and summary of the potential molecular mechanisms underlying ferroptosis in neurodegenerative diseases, aiming to elucidate the disease progression of neurodegeneration. Additionally, we discuss potential therapeutic agents that modulate ferroptosis with the goal of identifying novel drug molecules for the treatment of neurodegenerative disorders.

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

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

Mining on Alzheimer's diseases related knowledge graph to identity potential AD-related semantic triples for drug repurposing

BACKGROUND

To date, there are no effective treatments for most neurodegenerative diseases. Knowledge graphs can provide comprehensive and semantic representation for heterogeneous data, and have been successfully leveraged in many biomedical applications including drug repurposing. Our objective is to construct a knowledge graph from literature to study the relations between Alzheimer's disease (AD) and chemicals, drugs and dietary supplements in order to identify opportunities to prevent or delay neurodegenerative progression. We collected biomedical annotations and extracted their relations using SemRep via SemMedDB. We used both a BERT-based classifier and rule-based methods during data preprocessing to exclude noise while preserving most AD-related semantic triples. The 1,672,110 filtered triples were used to train with knowledge graph completion algorithms (i.e., TransE, DistMult, and ComplEx) to predict candidates that might be helpful for AD treatment or prevention.

RESULTS

Among three knowledge graph completion models, TransE outperformed the other two (MR = 10.53, Hits@1 = 0.28). We leveraged the time-slicing technique to further evaluate the prediction results. We found supporting evidence for most highly ranked candidates predicted by our model which indicates that our approach can inform reliable new knowledge.

CONCLUSION

This paper shows that our graph mining model can predict reliable new relationships between AD and other entities (i.e., dietary supplements, chemicals, and drugs). The knowledge graph constructed can facilitate data-driven knowledge discoveries and the generation of novel hypotheses.

Neuroprotective Function of Rasagiline and Selegiline, Inhibitors of Type B Monoamine Oxidase, and Role of Monoamine Oxidases in Synucleinopathies

Synucleinopathies are a group of neurodegenerative disorders caused by the accumulation of toxic species of α-synuclein. The common clinical features are chronic progressive decline of motor, cognitive, behavioral, and autonomic functions. They include Parkinson’s disease, dementia with Lewy body, and multiple system atrophy. Their etiology has not been clarified and multiple pathogenic factors include oxidative stress, mitochondrial dysfunction, impaired protein degradation systems, and neuroinflammation. Current available therapy cannot prevent progressive neurodegeneration and “disease-modifying or neuroprotective” therapy has been proposed. This paper presents the molecular mechanisms of neuroprotection by the inhibitors of type B monoamine oxidase, rasagiline and selegiline. They prevent mitochondrial apoptosis, induce anti-apoptotic Bcl-2 protein family, and pro-survival brain- and glial cell line-derived neurotrophic factors. They also prevent toxic oligomerization and aggregation of α-synuclein. Monoamine oxidase is involved in neurodegeneration and neuroprotection, independently of the catalytic activity. Type A monoamine oxidases mediates rasagiline-activated signaling pathways to induce neuroprotective genes in neuronal cells. Multi-targeting propargylamine derivatives have been developed for therapy in various neurodegenerative diseases. Preclinical studies have presented neuroprotection of rasagiline and selegiline, but beneficial effects have been scarcely presented. Strategy to improve clinical trials is discussed to achieve disease-modification in synucleinopathies.

Functionalization strategies of polymeric nanoparticles for drug delivery in Alzheimer’s disease: Current trends and future perspectives

Alzheimer’s disease (AD), the most common form of dementia, is a progressive and multifactorial neurodegenerative disorder whose primary causes are mostly unknown. Due to the increase in life expectancy of world population, including developing countries, AD, whose incidence rises dramatically with age, is at the forefront among neurodegenerative diseases. Moreover, a definitive cure is not yet within reach, imposing substantial medical and public health burdens at every latitude. Therefore, the effort to devise novel and effective therapeutic strategies is still of paramount importance. Genetic, functional, structural and biochemical studies all indicate that new and efficacious drug delivery strategies interfere at different levels with various cellular and molecular targets. Over the last few decades, therapeutic development of nanomedicine at preclinical stage has shown to progress at a fast pace, thus paving the way for its potential impact on human health in improving prevention, diagnosis, and treatment of age-related neurodegenerative disorders, including AD. Clinical translation of nano-based therapeutics, despite current limitations, may present important advantages and innovation to be exploited in the neuroscience field as well. In this state-of-the-art review article, we present the most promising applications of polymeric nanoparticle-mediated drug delivery for bypassing the blood-brain barrier of AD preclinical models and boost pharmacological safety and efficacy. In particular, novel strategic chemical functionalization of polymeric nanocarriers that could be successfully employed for treating AD are thoroughly described. Emphasis is also placed on nanotheranostics as both potential therapeutic and diagnostic tool for targeted treatments. Our review highlights the emerging role of nanomedicine in the management of AD, providing the readers with an overview of the nanostrategies currently available to develop future therapeutic applications against this chronic neurodegenerative disease.

Oxygen Sensing and Signaling in Alzheimer's Disease: A Breathtaking Story!

Oxygen sensing and homeostasis is indispensable for the maintenance of brain structural and functional integrity. Under low-oxygen tension, the non-diseased brain has the ability to cope with hypoxia by triggering a homeostatic response governed by the highly conserved hypoxia-inducible family (HIF) of transcription factors. With the advent of advanced neuroimaging tools, it is now recognized that cerebral hypoperfusion, and consequently hypoxia, is a consistent feature along the Alzheimer's disease (AD) continuum. Of note, the reduction in cerebral blood flow and tissue oxygenation detected during the prodromal phases of AD, drastically aggravates as disease progresses. Within this scenario a fundamental question arises: How HIF-driven homeostatic brain response to hypoxia "behaves" during the AD continuum? In this sense, the present review is aimed to critically discuss and summarize the current knowledge regarding the involvement of hypoxia and HIF signaling in the onset and progression of AD pathology. Importantly, the promises and challenges of non-pharmacological and pharmacological strategies aimed to target hypoxia will be discussed as a new "hope" to prevent and/or postpone the neurodegenerative events that occur in the AD brain.

Redox-Active Metal Ions and Amyloid-Degrading Enzymes in Alzheimer's Disease

Redox-active metal ions, Cu(I/II) and Fe(II/III), are essential biological molecules for the normal functioning of the brain, including oxidative metabolism, synaptic plasticity, myelination, and generation of neurotransmitters. Dyshomeostasis of these redox-active metal ions in the brain could cause Alzheimer’s disease (AD). Thus, regulating the levels of Cu(I/II) and Fe(II/III) is necessary for normal brain function. To control the amounts of metal ions in the brain and understand the involvement of Cu(I/II) and Fe(II/III) in the pathogenesis of AD, many chemical agents have been developed. In addition, since toxic aggregates of amyloid-β (Aβ) have been proposed as one of the major causes of the disease, the mechanism of clearing Aβ is also required to be investigated to reveal the etiology of AD clearly. Multiple metalloenzymes (e.g., neprilysin, insulin-degrading enzyme, and ADAM10) have been reported to have an important role in the degradation of Aβ in the brain. These amyloid degrading enzymes (ADE) could interact with redox-active metal ions and affect the pathogenesis of AD. In this review, we introduce and summarize the roles, distributions, and transportations of Cu(I/II) and Fe(II/III), along with previously invented chelators, and the structures and functions of ADE in the brain, as well as their interrelationships.

Structural exploration of multifunctional monoamine oxidase B inhibitors as potential drug candidates against Alzheimer's disease

AD is one of the most typical neurodegenerative disorders that suffer many seniors worldwide. Recently, MAO inhibitors have received increasing attention not only for their roles involved in monoamine neurotransmitters metabolism and oxidative stress but also for their additional neuroprotective and neurorescue effects against AD. The curiosity in MAO inhibitors is reviving, and novel MAO-B inhibitors recently developed with ancillary activities (e.g., Aβ aggregation and AChE inhibition, anti-ROS and chelating activities) have been proposed as multitarget drugs foreshadowing a positive outlook for the treatment of AD. The current review describes the recent development of the design, synthesis, and screening of multifunctional ligands based on MAO-B inhibition for AD therapy. Structure-activity relationships and rational design strategies of the synthetic or natural product derivatives (chalcones, coumarins, chromones, and homoisoflavonoids) are discussed.

N-Propargylamine-hydroxypyridinone hybrids as multitarget agents for the treatment of Alzheimer's disease

AD is a progressive brain disorder. Because of the lack of remarkable single-target drugs against neurodegenerative disorders, the multitarget-directed ligand strategy has received attention as a promising therapeutic approach. Herein, we rationally designed twenty-nine hybrids of N-propargylamine-hydroxypyridinone. The designed hybrids possessed excellent iron-chelating activity (pFe³⁺ = 17.09-22.02) and potent monoamine oxidase B inhibitory effects. Various biological evaluations of the optimal compound 6b were performed step by step, including inhibition screening of monoamine oxidase (hMAO-B IC₅₀ = 0.083 ± 0.001 µM, hMAO-A IC₅₀ = 6.11 ± 0.08 µM; SI = 73.5), prediction of blood-brain barrier permeability and mouse behavioral research. All of these favorable results proved that the N-propargylamine-hydroxypyridinone scaffold is a promising structure for the discovery of multitargeted ligands for AD therapy.

Targeting Alzheimer's disease with multimodal polypeptide-based nanoconjugates

Alzheimer's disease (AD), the most prevalent form of dementia, remains incurable mainly due to our failings in the search for effective pharmacological strategies. Here, we describe the development of targeted multimodal polypeptide-based nanoconjugates as potential AD treatments. Treatment with polypeptide nanoconjugates bearing propargylamine moieties and bisdemethoxycurcumin or genistein afforded neuroprotection and displayed neurotrophic effects, as evidenced by an increase in dendritic density of pyramidal neurons in organotypic hippocampal culture. The additional conjugation of the Angiopep-2 targeting moiety enhanced nanoconjugate passage through the blood-brain barrier and modulated brain distribution with nanoconjugate accumulation in neurogenic areas, including the olfactory bulb. Nanoconjugate treatment effectively reduced neurotoxic β amyloid aggregate levels and rescued impairments to olfactory memory and object recognition in APP/PS1 transgenic AD model mice. Overall, this study provides a description of a targeted multimodal polyglutamate-based nanoconjugate with neuroprotective and neurotrophic potential for AD treatment.

In Silico Prediction of the Toxic Potential of Neuroprotective Bifunctional Molecules Based on Chiral N-Propargyl-1,2-amino Alcohol Derivatives

N-Propargylamines are useful synthetic scaffolds for the synthesis of bioactive molecules, and in addition, they possess important pharmacological activities. We obtained several neuroprotective molecules, chiral 1,2-amino alcohols and 1,2-diamines, able to reduce by almost 70% the rotenone and oligomycin A-induced damage in SH-SY5Y cells. Furthermore, some molecules assessed also counteracted the toxicity evoked by the Ser/Thr phosphatase inhibitor okadaic acid. Before extrapolating these data to preclinical studies, we analyze the molecules through an in silico prediction system to detect carcinogenicity risk or other toxic effects. In light of these promising results, these molecules may be considered as a lead family of neuroprotective and relatively safe compounds.

Porphyromonas Gingivalis May Seek the Alzheimer's Disease Brain to Acquire Iron from Its Surplus

Iron accumulates in the brain of subjects with Alzheimer’s disease (AD). Here it promotes the aggregation of amyloid-β plaques in which it is abundant. Iron induces amyloid-β neurotoxicity by damaging free radicals and causing oxidative stress in brain areas with neurodegeneration. It can also bind to tau in AD and enhance the toxicity of tau through co-localization with neurofibrillary tangles and induce accumulation of these tangles. Porphyromonas gingivalis is a key oral pathogen in the widespread biofilm-induced disease “chronic” periodontitis, and recently, has been suggested to have an important role in the pathogenesis of AD. P. gingivalis has an obligate requirement for iron. The current paper suggests that P. gingivalis seeks the AD brain, where it has been identified, to satisfy this need. If this is correct, iron chelators binding iron could have beneficial effects in the treatment of AD. Indeed, studies from both animal AD models and humans with AD have indicated that iron chelators, e.g., lactoferrin, can have such effects. Lactoferrin can also inhibit P. gingivalis growth and proteinases and its ability to form biofilm.

Iron and Ferroptosis as Therapeutic Targets in Alzheimer's Disease

Alzheimer's disease (AD), one of the most common neurodegenerative diseases worldwide, has a devastating personal, familial, and societal impact. In spite of profound investment and effort, numerous clinical trials targeting amyloid-β, which is thought to have a causative role in the disease, have not yielded any clinically meaningful success to date. Iron is an essential cofactor in many physiological processes in the brain. An extensive body of work links iron dyshomeostasis with multiple aspects of the pathophysiology of AD. In particular, regional iron load appears to be a risk factor for more rapid cognitive decline. Existing iron-chelating agents have been in use for decades for other indications, and there are preliminary data that some of these could be effective in AD. Many novel iron-chelating compounds are under development, some with in vivo data showing potential Alzheimer's disease-modifying properties. This heretofore underexplored therapeutic class has considerable promise and could yield much-needed agents that slow neurodegeneration in AD.

The essential elements of Alzheimer's disease

Treatments for Alzheimer’s disease (AD) directed against the prominent amyloid plaque neuropathology are yet to be proved effective despite many phase 3 clinical trials. There are several other neurochemical abnormalities that occur in the AD brain that warrant renewed emphasis as potential therapeutic targets for this disease. Among those are the elementomic signatures of iron, copper, zinc, and selenium. Here, we review these essential elements of AD for their broad potential to contribute to Alzheimer’s pathophysiology, and we also highlight more recent attempts to translate these findings into therapeutics. A reinspection of large bodies of discovery in the AD field, such as this, may inspire new thinking about pathogenesis and therapeutic targets.

Synthesis and biological evaluation of 1,2,4-triazole derivatives as potential neuroprotectant against ischemic brain injury

A series of 1,2,4-triazole derivatives 1-14 was synthesized to investigate their neuroprotective effects and mechanisms of action. Compounds 5-11 noticeably protected PC12 cells from the cytotoxicity of H2O2 or sodium nitroprusside (SNP). Compound 11 was the most effective derivative. Compound 11 chelated Fe (II) iron, scavenged reactive oxygen species (ROS), and restored the mitochondrial membrane potential (MMP). Moreover, it enhanced the activity of the antioxidant defense system by increasing the serum level of superoxide dismutase (SOD) and promoting the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). Compound 11 caused certain improvements in behavior, the cerebral infarction area, and serum levels of biochemical indicators (TNF-α, IL-1β, SOD and MDA) in a rat MCAO model. The lethal dose (LD50) of compound 11 in mice receiving intraperitoneal injections was greater than 400 mg/kg. Meanwhile, pharmacokinetic experiments revealed high bioavailability of this compound after both oral and intravenous administration (F = 60.76%, CL = 0.014 mg/kg/h) and a longer half-life (4.26 and 5.11 h after oral and intravenous administration, respectively). Based on these findings, compound 11 may be a promising neuroprotectant for the treatment of ischemic stroke.

Propargylamine-derived multi-target directed ligands for Alzheimer's disease therapy

Current options for the treatment of Alzheimeŕs disease have been restricted to prescription of acetylcholinesterase inhibitors or N-methyl-d-aspartate receptor antagonist, memantine. Propargylamine-derived multi-target directed ligands, such as ladostigil, M30, ASS234 and contilisant, involve different pathways. Apart from acting as inhibitors of both cholinesterases and monoamine oxidases, they show improvement of cognitive impairment, antioxidant activities, enhancement of iron-chelating activities, protect against tau hyperphosphorylation, block metal-associated oxidative stress, regulate APP and Aβ expression processing by the non-amyloidogenic α-secretase pathway, suppress mitochondrial permeability transition pore opening, and coordinate protein kinase C signaling and Bcl-2 family proteins. Other hybrid propargylamine derivatives are also reported.

Hepcidin and its therapeutic potential in neurodegenerative disorders

Abnormally high brain iron, resulting from the disrupted expression or function of proteins involved in iron metabolism in the brain, is an initial cause of neuronal death in neuroferritinopathy and aceruloplasminemia, and also plays a causative role in at least some of the other neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, and Friedreich's ataxia. As such, iron is believed to be a novel target for pharmacological intervention in these disorders. Reducing iron toward normal levels or hampering the increases in iron associated with age in the brain is a promising therapeutic strategy for all iron-related neurodegenerative disorders. Hepcidin is a crucial regulator of iron homeostasis in the brain. Recent studies have suggested that upregulating brain hepcidin levels can significantly reduce brain iron content through the regulation of iron transport protein expression in the blood-brain barrier and in neurons and astrocytes. In this review, we focus on the discussion of the therapeutic potential of hepcidin in iron-associated neurodegenerative diseases and also provide a systematic overview of recent research progress on how misregulated brain iron metabolism is involved in the development of multiple neurodegenerative disorders.

Metal Chelation Therapy and Parkinson's Disease: A Critical Review on the Thermodynamics of Complex Formation between Relevant Metal Ions and Promising or Established Drugs

The present review reports a list of approximately 800 compounds which have been used, tested or proposed for Parkinson’s disease (PD) therapy in the year range 2014–2019 (April): name(s), chemical structure and references are given. Among these compounds, approximately 250 have possible or established metal-chelating properties towards Cu(II), Cu(I), Fe(III), Fe(II), Mn(II), and Zn(II), which are considered to be involved in metal dyshomeostasis during PD. Speciation information regarding the complexes formed by these ions and the 250 compounds has been collected or, if not experimentally available, has been estimated from similar molecules. Stoichiometries and stability constants of the complexes have been reported; values of the cologarithm of the concentration of free metal ion at equilibrium (pM), and of the dissociation constant K_d (both computed at pH = 7.4 and at total metal and ligand concentrations of 10⁻⁶ and 10⁻⁵ mol/L, respectively), charge and stoichiometry of the most abundant metal–ligand complexes existing at physiological conditions, have been obtained. A rigorous definition of the reported amounts is given, the possible usefulness of this data is described, and the need to characterize the metal–ligand speciation of PD drugs is underlined.

The correlation between accumulation of amyloid beta with enhanced neuroinflammation and cognitive impairment after intraventricular hemorrhage

OBJECTIVE

Intraventricular hemorrhage (IVH) is found in approximately 40% of intracerebral hemorrhages and is associated with increased mortality and poor functional outcome. Cognitive impairment is one of the complications and occurs due to various pathological changes. Amyloid beta (Aβ) accumulation and neuroinflammation, and the Alzheimer disease–like pathology, may contribute to cognitive impairment. Iron, the degradation product of hemoglobin, correlates with Aβ. In this study, the authors investigated the correlation between Aβ accumulation with enhanced neuroinflammation and cognitive impairment in a rat model of IVH.

METHODS

Nine male Sprague-Dawley rats underwent an intraventricular injection of autologous blood. Another 9 rats served as controls. Cognitive function was assessed by the Morris water maze and T-maze rewarded alternation tests. Biomarkers of Aβ accumulation, neuroinflammation, and c-Jun N-terminal kinase (JNK) activation were examined.

RESULTS

Cognitive function was impaired in the autologous blood injection group compared with the control group. In the blood injection group, Aβ accumulation was observed, with a co-located correlation between iron storage protein ferritin and Aβ. Beta-site amyloid precursor protein cleaving enzyme–1 (BACE1) activity was elevated. Microgliosis and astrogliosis were observed in hippocampal CA1, CA2, CA3, and dentate gyrus areas, with elevated proinflammatory cytokines tumor necrosis factor–α and interleukin-1. Protein levels of phosphorylated JNK were increased after blood injection.

CONCLUSIONS

Aβ accumulation and enhanced neuroinflammation have a role in cognitive impairment after IVH. A potential therapeutic method requires further investigation.

Rational design, cognition and neuropathology evaluation of QTC-4-MeOBnE in a streptozotocin-induced mouse model of sporadic Alzheimer's disease

Alzheimer’s disease (AD) is a multifactorial pathology characterized by amyloid deposits, neurofibrillary formation, oxidative stress and cholinergic system dysfunction. In this sense, here we report the rational design of a multi-target directed ligand (MTDL) for AD based on virtual screening and bioinformatic analyses, exploring the molecular targets β-secretase (BACE-1), glycogen synthase kinase-3β (GSK-3β) and acetylcholinesterase (AChE). After this screening, the compound with higher molecular docking affinity was selected, the 1-(7-chloroquinolin-4-yl)-N-(4-methoxybenzyl)-5-methyl-1H-1,2,3-triazole-4 carboxamide(QTC-4-MeOBnE). To further our studies, the protective effect of QTC-4-MeOBnE (0.1 and 1 mg/kg for 20 days) on STZ-induced sporadic AD mice was determined. QTC-4-MeOBnE pretreatment attenuated cognitive and memory deficit induced by STZ in an object recognition test, Y-maze, social recognition test and step-down passive avoidance. The mechanisms underlying this action might be attributed to the reduction of lipid peroxidation and reactive species formation in the prefrontal cortex and hippocampus of mice submitted to STZ. In addition, QTC-4-MeOBnE pretreatment abolished the up-regulation of AChE activity and the overexpression of GSK 3β and genes involved in amyloid cascade such as BACE-1, protein precursor amyloid, у-secretase, induced by STZ. Moreover, toxicological parameters were not modified by QTC-4-MeOBnE chronic treatment. This evidence suggests that QTC-4-MeOBnE exerts its therapeutic effect through multiple pathways involved in AD.

Iron and manganese-related CNS toxicity: mechanisms, diagnosis and treatment

INTRODUCTION

Iron (Fe) and manganese (Mn) are essential nutrients for humans. They act as cofactors for a variety of enzymes. In the central nervous system (CNS), these two metals are involved in diverse neurological activities. Dyshomeostasis may interfere with the critical enzymatic activities, hence altering the neurophysiological status and resulting in neurological diseases. Areas covered: In this review, the authors cover the molecular mechanisms of Fe/Mn-induced toxicity and neurological diseases, as well as the diagnosis and potential treatment. Given that both Fe and Mn are abundant in the earth crust, nutritional deficiency is rare. In this review the authors focus on the neurological disorders associated with Mn and Fe overload. Expert commentary: Oxidative stress and mitochondrial dysfunction are the primary molecular mechanism that mediates Fe/Mn-induced neurotoxicity. Although increased Fe or Mn concentrations have been found in brain of patients, it remains controversial whether the elevated metal amounts are the primary cause or secondary consequence of neurological diseases. Currently, treatments are far from satisfactory, although chelation therapy can significantly decrease brain Fe and Mn levels. Studies to determine the primary cause and establish the molecular mechanism of toxicity may help to adapt more comprehensive and satisfactory treatments in the future.

Immobilized Gold Nanoparticles Prepared from Gold(III)-Containing Ionic Liquids on Silica: Application to the Sustainable Synthesis of Propargylamines

A cycloaurated phosphinothioic amide gold(III) complex was supported on amorphous silica with the aid of an imidazolium ionic liquid (IL) physisorbed in the SiO₂ pores (SiO₂⁻IL) and covalently bonded to the SiO₂ (SiO₂@IL). Gold(0) nanoparticles (AuNPs) were formed in situ and subsequently immobilized on the SiO₂⁻IL/SiO₂@IL phase. The resulting catalytic systems Au⁻SiO₂⁻IL and Au⁻SiO₂@IL promoted the solvent-free A³ coupling reaction of alkynes, aldehydes, and amines in high yields under solvent-free conditions with very low catalyst loading and without the use of additives. The Au⁻SiO₂@IL catalyst showed good recyclability and could be reused at least five times with yields of propargylamines of ≥80%. This synthetic method provides a green and low cost way to effectively prepare propargylamines. Additionally, 31P high resolution magic angle spinning (HRMAS) NMR spectroscopy is introduced as a simple technique to establish the Au loading of the catalyst.

Monoamine oxidase inhibitors, and iron chelators in depressive illness and neurodegenerative diseases

In early 1920s, tyramine oxidase was discovered that metabolized tyramine and in 1933 Blaschko demonstrated that this enzyme also metabolized adrenaline, noradrenaline and dopamine. Zeller gave it the name monoamine oxidase (MAO) to distinguish it from the enzyme that oxidatively deaminated diamines. MAO was recognized as an enzyme of crucial interest to pharmacologists because it catalyzed the major inactivation pathway for the catecholamines (and, later, 5-hydroxytryptamine, as well). Within the few decade, the inhibitors of MAO were discovered and introduced for the treatment of depressive illness which was established clinically. However, the first clinical use exposed serious side effects, pharmacological interest in, and investigation of, MAO continued, resulting in the characterization of two forms, distinct forms, MAO-A and -B, and selective inhibitors for them. Selective inhibitors of MAO-B (selegiline, rasagiline and safinamide) have found a therapeutic role in the treatment of Parkinson's disease and reversible inhibitors of MAO-A offered antidepressant activity without the serious side effects of the earlier nonselective MAO inhibitors. Subsequent molecular pharmacological have also generated the concept of neuroprotection, reflecting the possibility of slowing, halting and maybe reversing, neurodegeneration in Parkinson's or Alzheimer's diseases. Increased levels of oxidative stress through the accumulation of iron in the Parkinsonian and Alzheimer brains has been suggested to be critical for the initiation and progress of neurodegeneration. Selective inhibition of brain MAO could contribute importantly to lowering such stress, preventing the formation of hydrogen peroxide. Interaction of Iron with hydrogen peroxide and lead to Fenton reaction and production of the most reactive radical, namely hydroxyl radical. There are complex interactions between free iron levels in brain and MAO, and cascade of neurotoxic events may have practical outcomes for depressive disorders and neurodegenerative diseases. As consequence recent novel therapeutic drugs for neurodegenerative diseases has led to the development of multi target drugs, that possess selective brain MAO A and B inhibitory moiety, iron chelating and antioxidant activities and the ability to increase brain levels of endogenous neurotrophins, such as BDNF, GDNF VEGF and erythropoietin and induce mitochondrial biogenesis.

New Perspectives in Iron Chelation Therapy for the Treatment of Neurodegenerative Diseases

Iron chelation has been introduced as a new therapeutic concept for the treatment of neurodegenerative diseases with features of iron overload. At difference with iron chelators used in systemic diseases, effective chelators for the treatment of neurodegenerative diseases must cross the blood–brain barrier. Given the promissory but still inconclusive results obtained in clinical trials of iron chelation therapy, it is reasonable to postulate that new compounds with properties that extend beyond chelation should significantly improve these results. Desirable properties of a new generation of chelators include mitochondrial destination, the center of iron-reactive oxygen species interaction, and the ability to quench free radicals produced by the Fenton reaction. In addition, these chelators should have moderate iron binding affinity, sufficient to chelate excessive increments of the labile iron pool, estimated in the micromolar range, but not high enough to disrupt physiological iron homeostasis. Moreover, candidate chelators should have selectivity for the targeted neuronal type, to lessen unwanted secondary effects during long-term treatment. Here, on the basis of a number of clinical trials, we discuss critically the current situation of iron chelation therapy for the treatment of neurodegenerative diseases with an iron accumulation component. The list includes Parkinson’s disease, Friedreich’s ataxia, pantothenate kinase-associated neurodegeneration, Huntington disease and Alzheimer’s disease. We also review the upsurge of new multifunctional iron chelators that in the future may replace the conventional types as therapeutic agents for the treatment of neurodegenerative diseases.

Iron metabolism in diabetes-induced Alzheimer's disease: a focus on insulin resistance in the brain

Alzheimer's disease (AD) is characterized by an excessive accumulation of toxic amyloid beta (Aβ) plaques and memory dysfunction. The onset of AD is influenced by age, genetic background, and impaired glucose metabolism in the brain. Several studies have demonstrated that diabetes involving insulin resistance and glucose tolerance could lead to AD, ultimately resulting in cognitive dysfunction. Even though the relationship between diabetes and AD was indicated by significant evidences, the critical mechanisms and metabolic alterations in diabetes induced AD are not clear until now. Recently, iron metabolism has been shown to play multiple roles in the central nervous system (CNS). Iron deficiency and overload are associated with neurodegenerative diseases. Iron binds to Aβ and subsequently regulates Aβ toxicity in the CNS. In addition, previous studies have shown that iron is involved in the aggravation of insulin resistance. Considering these effects of iron metabolism in CNS, we expect that iron metabolism may play crucial roles in diabetic AD brain. Thus, we review the recent evidence regarding the relationship between diabetes-induced AD and iron metabolism.

Anti-Alzheimers activity and molecular mechanism of albumin-derived peptides against AChE and BChE

Alzheimer's disease (AD) is a global health issue affecting millions of elderly people worldwide. The aim of the present study was to identify novel anti-AD peptides isolated from albumin. Anti-AD activities of the peptides were evaluated via inhibitory activities on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Furthermore, the potential molecular mechanisms of the KLPGF/AChE were investigated by CDOCKER of Discovery studio 2017. The results revealed that peptide KLPGF could effectively inhibit AChE with an inhibition rate of 61.23% at a concentration of 50 μg mL^-1. In addition, the peptide KLPGF came in contact with acylation sites and peripheral anion sites of AChE. The present study demonstrates that the peptide KLPGF could become a potential functional food intervention in AD.

Mitogen-activated protein kinase phosphatase 1 protects PC12 cells from amyloid beta-induced neurotoxicity

The mitogen-activated protein kinase (MAPK) signaling pathway plays an important role in the regulation of cell growth, proliferation, differentiation, transformation and death. Mitogen-activated protein kinase phosphatase 1 (MKP1) has an inhibitory effect on the p38MAPK and JNK pathways, but it is unknown whether it plays a role in Aβ-induced oxidative stress and neuronal inflammation. In this study, PC12 cells were infected with MKP1 shRNA, MKP1 lentivirus or control lentivirus for 12 hours, and then treated with 0.1, 1, 10 or 100 μM amyloid beta 42 (Aβ₄₂). The cell survival rate was measured using the cell counting kit-8 assay. MKP1, tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) mRNA expression levels were analyzed using quantitative real time-polymerase chain reaction. MKP1 and phospho-c-Jun N-terminal kinase (JNK) expression levels were assessed using western blot assay. Reactive oxygen species (ROS) levels were detected using 2′,7′-dichlorofluorescein diacetate. Mitochondrial membrane potential was measured using flow cytometry. Superoxide dismutase activity and malondialdehyde levels were evaluated using the colorimetric method. Lactate dehydrogenase activity was measured using a microplate reader. Caspase-3 expression levels were assessed by enzyme-linked immunosorbent assay. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase dUTP nick end labeling method. MKP1 overexpression inhibited Aβ-induced JNK phosphorylation and the increase in ROS levels. It also suppressed the Aβ-induced increase in TNF-α and IL-1β levels as well as apoptosis in PC12 cells. In contrast, MKP1 knockdown by RNA interference aggravated Aβ-induced oxidative stress, inflammation and cell damage in PC12 cells. Furthermore, the JNK-specific inhibitor SP600125 abolished this effect of MKP1 knockdown on Aβ-induced neurotoxicity. Collectively, these results show that MKP1 mitigates Aβ-induced apoptosis, oxidative stress and neuroinflammation by inhibiting the JNK signaling pathway, thereby playing a neuroprotective role.