Deferiprone ameliorates memory impairment in Scopolamine-treated rats: The impact of its iron-chelating effect on β-amyloid disposition

Iron homeostasis imbalance and ferroptosis in brain diseases

Brain iron homeostasis is maintained through the normal function of blood-brain barrier and iron regulation at the systemic and cellular levels, which is fundamental to normal brain function. Excess iron can catalyze the generation of free radicals through Fenton reactions due to its dual redox state, thus causing oxidative stress. Numerous evidence has indicated brain diseases, especially stroke and neurodegenerative diseases, are closely related to the mechanism of iron homeostasis imbalance in the brain. For one thing, brain diseases promote brain iron accumulation. For another, iron accumulation amplifies damage to the nervous system and exacerbates patients' outcomes. In addition, iron accumulation triggers ferroptosis, a newly discovered iron-dependent type of programmed cell death, which is closely related to neurodegeneration and has received wide attention in recent years. In this context, we outline the mechanism of a normal brain iron metabolism and focus on the current mechanism of the iron homeostasis imbalance in stroke, Alzheimer's disease, and Parkinson's disease. Meanwhile, we also discuss the mechanism of ferroptosis and simultaneously enumerate the newly discovered drugs for iron chelators and ferroptosis inhibitors.

Iron metabolism: An emerging therapeutic target underlying the anti-Alzheimer's disease effect of ginseng

Finding neuroprotective drugs with fewer side effects and more efficacy has become a major problem as the global prevalence of Alzheimer's disease (AD) rises. Natural drugs have risen to prominence as potential medication candidates. Ginseng has a long history of use in China, and it has a wide range of pharmacological actions that can help with neurological issues. Iron loaded in the brain has been linked to AD pathogenesis. We reviewed the regulation of iron metabolism and its studies in AD and explored how ginseng might regulate iron metabolism and prevent or treat AD. Researchers utilized network pharmacology analysis to identify key factive components of ginseng that protect against AD by regulating ferroptosis. Ginseng and its active ingredients may benefit AD by regulating iron metabolism and targeting ferroptosis genes to inhibit the ferroptosis process. The results present new ideas for ginseng pharmacological studies and initiatives for further research into AD-related drugs. To provide comprehensive information on the neuroprotective use of ginseng to modulate iron metabolism, reveal its potential to treat AD, and provide insights for future research opportunities.

Vildagliptin restores cognitive function and mitigates hippocampal neuronal apoptosis in cisplatin-induced chemo-brain: Imperative roles of AMPK/Akt/CREB/ BDNF signaling cascades

Cisplatin (CP) is a broad-spectrum antineoplastic agent used to treat many human cancers. Nonetheless, most patients receiving CP suffer from cognitive deficits, a phenomenon termed "chemo-brain". Recently, vildagliptin (Vilda), a DPP-4 inhibitor, has demonstrated promising neuroprotective properties against various neurological diseases. Therefore, the present study aims to investigate the potential neuroprotective properties of Vilda against CP-induced neurotoxicity and elucidate the underlying molecular mechanisms. Chemo-brain was induced in Sprague-Dawley rats by i.p injection of CP at a dose of 5 mg/kg once weekly for four weeks. Vilda was administered daily at a dose (10 mg/kg; P.O) for four weeks. The results revealed that Vilda restored the cognitive function impaired by CP, as assessed by the Morris water maze, Y-maze, and passive avoidance tests. Moreover, Vilda alleviated the CP-induced neurodegeneration, as shown by toluidine blue staining, besides markedly reduced amyloid plaque deposition, as evidenced by Congo red staining. Notably, Vilda boosted cholinergic neurotransmission through the downregulation of the acetylcholinesterase enzyme. In addition, the neuroprotective mechanisms of Vilda include diminishing oxidative stress by reducing MDA levels while raising GSH levels and SOD activity, repressing neuronal apoptosis as shown by elevated Bcl-2 levels together with diminished Bax and caspase-3 expressions, inhibiting neuroinflammation as shown by decreased GFAP expression, and finally boosting hippocampal neurogenesis and survival by upregulating expressions of BDNF and PCNA. These effects were mainly mediated by activating AMPK/Akt/CREB signaling cascades. In summary, Vilda can be considered a promising candidate for guarding against CP-induced chemo-brain and neurodegeneration, thus improving the quality of life of cancer patients.

Non-Enzymatic Antioxidants against Alzheimer's Disease: Prevention, Diagnosis and Therapy

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory loss and cognitive decline. Although substantial research has been conducted to elucidate the complex pathophysiology of AD, the therapeutic approach still has limited efficacy in clinical practice. Oxidative stress (OS) has been established as an early driver of several age-related diseases, including neurodegeneration. In AD, increased levels of reactive oxygen species mediate neuronal lipid, protein, and nucleic acid peroxidation, mitochondrial dysfunction, synaptic damage, and inflammation. Thus, the identification of novel antioxidant molecules capable of detecting, preventing, and counteracting AD onset and progression is of the utmost importance. However, although several studies have been published, comprehensive and up-to-date overviews of the principal anti-AD agents harboring antioxidant properties remain scarce. In this narrative review, we summarize the role of vitamins, minerals, flavonoids, non-flavonoids, mitochondria-targeting molecules, organosulfur compounds, and carotenoids as non-enzymatic antioxidants with AD diagnostic, preventative, and therapeutic potential, thereby offering insights into the relationship between OS and neurodegeneration.

Ferroptosis: a potential therapeutic target for Alzheimer's disease

The most prevalent dementia-causing neurodegenerative condition is Alzheimer's disease (AD). The aberrant buildup of amyloid β and tau hyperphosphorylation are the two most well-known theories about the mechanisms underlying AD development. However, a significant number of pharmacological clinical studies conducted around the world based on the two aforementioned theories have not shown promising outcomes, and AD is still not effectively treated. Ferroptosis, a non-apoptotic programmed cell death defined by the buildup of deadly amounts of iron-dependent lipid peroxides, has received more attention in recent years. A wealth of data is emerging to support the role of iron in the pathophysiology of AD. Cell line and animal studies applying ferroptosis modulators to the treatment of AD have shown encouraging results. Based on these studies, we describe in this review the underlying mechanisms of ferroptosis; the role that ferroptosis plays in AD pathology; and summarise some of the research advances in the treatment of AD with ferroptosis modulators. We hope to contribute to the clinical management of AD.

Ferroptosis inhibition by deferiprone, attenuates myelin damage and promotes neuroprotection in demyelinated optic nerve

Multiple sclerosis (MS) is a chronic inflammatory disease, which leads to focal demyelination in the brain and spinal cord. Studies showed that iron released during the course of myelin breakdown exacerbates tissue damage, which is in agreement with the features of iron-dependent cell death, ferroptosis. Here, we aimed to investigate the possible contribution of ferroptosis in the demyelinated optic nerve, and to explore the effectiveness of ferroptosis inhibitor, deferiprone (DFP), on the extent of demyelination, inflammation and axonal damage. For this purpose, focal demyelination was induced by injection of lysolecithin (LPC), into the optic nerve of male C57BL/6J mice. Afterward, optic nerves were harvested at different time points from as early as 6 h up to 7 days post-LPC injection. Next, to evaluate the effectiveness of DFP two groups of animals received daily intraperitoneal injection of DFP for 3 or 7 continuous days. Vehicle groups received saline. Iron deposition was observed at different time points post-LPC injection from 6 h to 7 days post injection. Examining ferroptosis markers showed a significant reduction in glutathione content along with increased level of malondialdehyde and upregulated ferroptosis marker genes at early time points after injection. Besides, DFP treatment during the inflammatory phase of the model resulted in decreased microgliosis and inflammation. Reduced demyelination, microgliosis and astrogliosis was shown in mice that received DFP for 7 days. Moreover, DFP protected against axonal damage and retinal ganglion cells loss. Our results suggest the possible contribution of ferroptosis pathway in the process of demyelination. The therapeutic strategies targeting iron deposition, e.g. DFP treatment might thus represent a promising therapeutic target for patients with MS.

The Potential Neuroprotective Effect of Cyperus esculentus L. Extract in Scopolamine-Induced Cognitive Impairment in Rats: Extensive Biological and Metabolomics Approaches

The aim of the present study is to investigate the phytochemical composition of tiger nut (TN) (Cyperus esculentus L.) and its neuroprotective potential in scopolamine (Scop)-induced cognitive impairment in rats. The UHPLC-ESI-QTOF-MS analysis enabled the putative annotation of 88 metabolites, such as saccharides, amino acids, organic acids, fatty acids, phenolic compounds and flavonoids. Treatment with TN extract restored Scop-induced learning and memory impairments. In parallel, TN extract succeeded in lowering amyloid beta, β-secretase protein expression and acetylcholine esterase (AChE) activity in the hippocampus of rats. TN extract decreased malondialdehyde levels, restored antioxidant levels and reduced proinflammatory cytokines as well as the Bax/Bcl2 ratio. Histopathological analysis demonstrated marked neuroprotection in TN-treated groups. In conclusion, the present study reveals that TN extract attenuates Scop-induced memory impairments by diminishing amyloid beta aggregates, as well as its anti-inflammatory, antioxidant, anti-apoptotic and anti-AChE activities.

Iron dyshomeostasis and ferroptosis in Alzheimer’s disease: Molecular mechanisms of cell death and novel therapeutic drugs and targets for AD

Alzheimer’s disease (AD) is a degenerative disease of the central nervous system that is the most common type of senile dementia. Ferroptosis is a new type of iron-dependent programmed cell death identified in recent years that is different from other cell death forms. Ferroptosis is induced by excessive accumulation of lipid peroxides and reactive oxygen species (ROS) in cells. In recent years, it has been found that ferroptosis plays an important role in the pathological process of AD. Iron dyshomeostasis contribute to senile plaques (SP) deposition and neurofibrillary tangles (NFTs). Iron metabolism imbalance in brain and the dysfunction of endogenous antioxidant systems including system Xc- and glutathione peroxidase (GPX) are closely related to the etiopathogenesis of AD. Dysfunction of nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy induced ferroptosis can accelerates the pathological process of AD. In addition, NRF2, through regulating the expression of a considerable number of genes related to ferroptosis, including genes related to iron and glutathione metabolism, plays an important role in the development of AD. Here, we review the potential interaction between AD and ferroptosis and the major pathways regulating ferroptosis in AD. We also review the active natural and synthetic compounds such as iron chelators, lipid peroxidation inhibitors and antioxidants available to treat AD by alleviating iron dyshomeostasis and preventing ferroptosis in mice and cell models to provide valuable information for the future treatment and prevention of AD.

Reversal of genetic brain iron accumulation by N,N'-bis(2-mercaptoethyl)isophthalamide, a lipophilic metal chelator, in mice

N,N'-bis(2-mercaptoethyl)isophthalamide (NBMI) is a novel lipophilic metal chelator and antioxidant used in mercury poisoning. Recent studies have suggested that NBMI may also bind to other metals such as lead and iron. Since NBMI can enter the brain, we evaluated if NBMI removes excess iron from the iron-loaded brain and ameliorates iron-induced oxidative stress. First, NBMI exhibited preferential binding to ferrous (Fe²⁺) iron with a negligible binding affinity to ferric (Fe³⁺) iron, indicating a selective chelation of labile iron. Second, NBMI protected SH-SY5Y human neuroblastoma cells from the cytotoxic effects of high iron. NBMI also decreased cellular labile iron and lessened the production of iron-induced reactive oxygen species in these cells. Deferiprone (DFP), a commonly used oral iron chelator, failed to prevent iron-induced cytotoxicity or labile iron accumulation. Next, we validated the efficacy of NBMI in Hfe H67D mutant mice, a mouse model of brain iron accumulation (BIA). Oral gavage of NBMI for 6 weeks decreased iron accumulation in the brain as well as liver, whereas DFP showed iron chelation only in the liver, but not in the brain. Notably, depletion of brain copper and anemia were observed in BIA mice treated with DFP, but not with NBMI, suggesting a superior safety profile of NBMI over DFP for long-term use. Collectively, our study demonstrates that NBMI provides a neuroprotective effect against BIA and has therapeutic potential for neurodegenerative diseases associated with BIA.

Ferroptosis as a mechanism of neurodegeneration in Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent form of dementia, with complex pathophysiology that is not fully understood. While β-amyloid plaque and neurofibrillary tangles define the pathology of the disease, the mechanism of neurodegeneration is uncertain. Ferroptosis is an iron-mediated programmed cell death mechanism characterised by phospholipid peroxidation that has been observed in clinical AD samples. This review will outline the growing molecular and clinical evidence implicating ferroptosis in the pathogenesis of AD, with implications for disease-modifying therapies.

Contributions of animal models of cognitive disorders to neuropsychopharmacology

Cognitive disorders and symptoms are key features of many mental and neurological diseases, with a large spectrum of impaired domains. Because of their possible evolution and detrimental functioning impact, they are a major pharmacological target for both symptomatic and disease-modifier drugs, while few cognitive enhancers have been marketed with an insufficient efficiency. It explains the need to model these cognitive disorders beyond the modelization of mental or neurological diseases themselves. According to the experimental strategy used to induce cognitive impairment, three categories of models have been identified: neurotransmission-driven models; pathophysiology-driven models; environment-driven models. These three categories of models reflect different levels of integration of endogenous and exogenous mechanisms underlying cognitive disorders in humans. Their comprehensive knowledge and illustration of their pharmacological modulation could help to propose a renewing strategy of drug development in central nervous system (CNS) field at a time when the academic and industrial invest seems to be declining despite the medical and social burden of brain diseases.

Therapeutic Potential of Multifunctional Derivatives of Cholinesterase Inhibitors

The aim of this work is to review tacrine analogues from the last three years, which were not included in the latest review work, donepezil and galantamine hybrids from 2015 and rivastigmine derivatives from 2014. In this account, we summarize the efforts toward the development and characterization of non-toxic inhibitors of cholinesterases based on mentioned drugs with various interesting additional properties such as antioxidant, decreasing β-amyloid plaque aggregation, nitric oxide production, pro-inflammatory cytokines release, monoamine oxidase-B activity, cytotoxicity and oxidative stress in vitro and in animal model that classify these hybrids as potential multifunctional therapeutic agents for Alzheimer's disease. Moreover, herein, we have described the cholinergic hypothesis, mechanisms of neurodegeneration and current pharmacotherapy of Alzheimer's disease based on the restoration of cholinergic function through blocking enzymes that break down acetylcholine.