Free radicals in Alzheimer's disease: Lipid peroxidation biomarkers

Associations between Brain Alpha-Tocopherol Stereoisomer Profile and Hallmarks of Brain Aging in Centenarians

Brain alpha-tocopherol (αT) concentration was previously reported to be inversely associated with neurofibrillary tangle (NFT) counts in specific brain structures from centenarians. However, the contribution of natural or synthetic αT stereoisomers to this relationship is unknown. In this study, αT stereoisomers were quantified in the temporal cortex (TC) of 47 centenarians in the Georgia Centenarian Study (age: 102.2 ± 2.5 years, BMI: 22.1 ± 3.9 kg/m2) and then correlated with amyloid plaques (diffuse and neuritic plaques; DPs, NPs) and NFTs in seven brain regions. The natural stereoisomer, RRR-αT, was the primary stereoisomer in all subjects, accounting for >50% of total αT in all but five subjects. %RRR was inversely correlated with DPs in the frontal cortex (FC) (ρ = -0.35, p = 0.032) and TC (ρ = -0.34, p = 0.038). %RSS (a synthetic αT stereoisomer) was positively correlated with DPs in the TC (ρ = 0.39, p = 0.017) and with NFTs in the FC (ρ = 0.37, p = 0.024), TC (ρ = 0.42, p = 0.009), and amygdala (ρ = 0.43, p = 0.008) after controlling for covariates. Neither RRR- nor RSS-αT were associated with premortem global cognition. Even with the narrow and normal range of BMIs, BMI was correlated with %RRR-αT (ρ = 0.34, p = 0.021) and %RSS-αT (ρ = -0.45, p = 0.002). These results providing the first characterization of TC αT stereoisomer profiles in centenarians suggest that DP and NFT counts, but not premortem global cognition, are influenced by the brain accumulation of specific αT stereoisomers. Further study is needed to confirm these findings and to determine the potential role of BMI in mediating this relationship.

Caspases in Alzheimer's Disease: Mechanism of Activation, Role, and Potential Treatment

With the aging of the population, treatment of conditions emerging in old age, such as neurodegenerative disorders, has become a major medical challenge. Of these, Alzheimer's disease, leading to cognitive dysfunction, is of particular interest. Neuronal loss plays an important role in the pathophysiology of this condition, and over the years, a great effort has been made to determine the role of various factors in this process. Unfortunately, until now, the exact pathomechanism of this condition remains unknown. However, the most popular theories associate AD with abnormalities in the Tau and β-amyloid (Aβ) proteins, which lead to their deposition and result in neuronal death. Neurons, like all cells, die in a variety of ways, among which pyroptosis, apoptosis, and necroptosis are associated with the activation of various caspases. It is worth mentioning that Tau and Aβ proteins are considered to be one of the caspase activators, leading to cell death. Moreover, the protease activity of caspases influences both of the previously mentioned proteins, Tau and Aβ, converting them into more toxic derivatives. Due to the variety of ways caspases impact the development of AD, drugs targeting caspases could potentially be useful in the treatment of this condition. Therefore, there is a constant need to search for novel caspase inhibitors and evaluate them in preclinical and clinical trials.

Psychobiotics for Mitigation of Neuro-Degenerative Diseases: Recent Advancements

Ageing is inevitable and poses a universal challenge for all living organisms, including humans. The human body experiences rapid cell division and metabolism until approximately 25 years of age, after which the accumulation of metabolic by-products and cellular damage leads to age-related diseases. Neurodegenerative diseases are of concern due to their irreversible nature, lack of effective treatment, and impact on society and the economy. Researchers are interested in finding drugs that can effectively alleviate ageing and age-related diseases without side-effects. Psychobiotics are a novel class of probiotic organisms and prebiotic interventions that confer mental health benefits to the host when taken appropriately. Psychobiotic strains affect functions related to the central nervous system (CNS) and behaviors mediated by the Gut-Brain-Axis (GBA) through various pathways. There is an increasing interest in researchers of these microbial-based psychopharmaceuticals. Psychobiotics have been reported to reduce neuronal ageing, inflammation, oxidative stress, and cortisol levels; increase synaptic plasticity and levels of neurotransmitters and antioxidants. The present review focuses on the manifestation of elderly neurodegenerative and mental disorders, particularly Alzheimer's disease (AD), Parkinson's disease (PD), and depression, and the current status of their potential alleviation through psychobiotic interventions, highlighting their possible mechanisms of action.

Aspartame-induced cognitive dysfunction: Unveiling role of microglia-mediated neuroinflammation and molecular remediation

Aspartame, an artificial sweetener, is consumed by millions of people globally. There are multiple reports of aspartame and its metabolites affecting cognitive functions in animal models and humans, which include learning problems, headaches, seizures, migraines, irritable moods, anxiety, depression, and insomnia. These cognitive deficits and associated symptoms are partly attributed to dysregulated excitatory and inhibitory neurotransmitter balance due to aspartate released from aspartame, resulting in an excitotoxic effect in neurons, leading to neuronal damage. However, microglia, a central immunocompetent cell type in brain tissue and a significant player in inflammation can contribute to the impact. Microglia rapidly respond to changes in CNS homeostasis. Aspartame consumption might affect the microglia phenotype directly via methanol-induced toxic effects and indirectly via aspartic acid-mediated excitotoxicity, exacerbating symptoms of cognitive decline. Long-term oral consumption of aspartame thus might change microglia's phenotype from ramified to activated, resulting in chronic or sustained activation, releasing excess pro-inflammatory molecules. This pro-inflammatory surge might lead to the degeneration of healthy neurons and other glial cells, impairing cognition. This review will deliberate on possible links and research gaps that need to be explored concerning aspartame consumption, ecotoxicity and microglia-mediated inflammatory cognitive impairment. The study covers a comprehensive analysis of the impact of aspartame consumption on cognitive function, considering both direct and indirect effects, including the involvement of microglia-mediated neuroinflammation. We also propose a novel intervention strategy involving tryptophan supplementation to mitigate cognitive decline symptoms in individuals with prolonged aspartame consumption, providing a potential solution to address the adverse effects of aspartame on cognitive function.

Recent Advances in Targeting Transition Metals (Copper, Iron, and Zinc) in Alzheimer's Disease

Changes in the transition metal homeostasis in the brain are closely linked with Alzheimer's disease (AD), including intraneuronal iron accumulation and extracellular copper and zinc pooling in the amyloid plague. The brain copper, zinc, and iron surplus are commonly acknowledged characteristics of AD, despite disagreements among some. This has led to the theory that oxidative stress resulting from abnormal homeostasis of these transition metals may be a causative explanation behind AD. In the nervous system, the interaction of metals with proteins appears to be an essential variable in the development or suppression of neurodegeneration. Chelation treatment may be an option for treating neurodegeneration induced by transition metal ion dyshomeostasis. Some clinicians even recommend using chelating agents as an adjunct therapy for AD. The current review also looks at the therapeutic strategies that have been attempted, primarily with metal-chelating drugs. Metal buildup in the nervous system, as reported in the AD, could be the result of compensatory mechanisms designed to improve metal availability for physiological functions.

Valorization and Repurposing of Citrus limetta Fruit Waste for Fabrication of Multifunctional AgNPs and Their Diverse Nanomedicinal Applications

Herein we propose an ecofriendly process for the biofabrication of AgNPs by applying fruit waste of Citrus limetta. The aqueous extracts from the peels of the fruit were used as green chelating and stabilizing agents. Structural, optical, vibrational, morphological, and magnetic properties were established using UV-Vis (ultraviolet visible spectroscopy), XRD (X-rays diffraction), FTIR (Fourier transformed infrared spectroscopy), EDS (energy dispersive spectroscopy), SEM (scanning electron microscopy), ESR (electron spin resonance), and PPMS (physical property management system), while the thermal properties were established using TGA/DTG (thermal gravimetric analysis/derivative thermogravimetry). XRD pattern revealed intense peaks with single-phase purity, while the Debye-Scherrer approximation revealed an average crystallite size of 33.18 nm. The W-H plot revealed the size of 55.2 nm and strain 2.68 × 10-4. FTIR spectra revealed the involvement of different functional groups and major IR vibrations were observed at 2329 cm-1, 2092 cm-1, 1794 cm-1, 1268 cm-1, and 754 cm-1. TGA/DTG revealed major weight loss events at 240 °C and 360 °C. SEM revealed spherical or quasi-spherical morphology, while EDS confirmed the presence of elemental silver. The M-H behavior for all measurement temperature shows diamagnetic behavior. Electron spin resonance (ESR) revealed a high proportion of free electrons. Furthermore, the pharmacognostic and nanomedicinal potential CL-AgNPs was established using multiple in vitro and in vivo bioassays. The in vivo wound healing assays in mice revealed excellent healing potential which were similar to positive control. The percent wound healing is reported to be 93% on the 14th day of incision after application of CL-AgNPs. Bioassays were performed to assess enzyme inhibition potential of the CL-AgNPs for Alzheimer disease and antidiabetic applications. The AChE and BChE potential of the CL-AgNPs was highest at 1000 µg mL-1, i.e., 92% and 56%, respectively. The α-glucosidase inhibition potential for the CL-AgNPs was higher as compared to the α-glucosidase, while the DPPH free radical scavenging was reported to be 70% to 11% at varying concentrations between 1000 and 62.5 µg mL-1. Overall, our results indicate that the waste fruit peels can be a sustainable and eco-friendly resource of synthesis of the multifunctional nanoparticles.

Redox-associated changes in healthy individuals at risk of Alzheimer's disease. A ten-year follow-up study

Carrying an allele 4 of the apolipoprotein E (ApoE) is the best-established genetic risk factor to develop Alzheimer's disease (AD). Fifty percent of ApoE4/4 individuals develop the disease at 70 years of age. ApoE3/4 carriers have a lower risk of developing the disease, still 50% of them suffer AD at around 80 years. In a previous study we showed that healthy young individuals, who had a parent with AD and were carriers of at least one ApoE4 allele displayed reductive stress. This was evidenced as a decrease in oxidative markers, such as oxidized glutathione, p-p38, and NADP+/NADPH ratio, and an increase of antioxidant enzymes, such as glutathione peroxidase (Gpx1) and both the catalytic and regulatory subunits of glutamyl-cysteinyl (GCLM and GCLC). Moreover, we found an increase in stress-related proteins involved in tau physiopathology. Now, 10 years later, we have conducted a follow-up study measuring the same parameters in the same cohort. Our results show that reductive stress has reversed, as we could now observe an increase in lipid peroxidation and in the oxidation of glutathione along with a decrease in the expression of Gpx1 and SOD1 antioxidant enzymes in ApoE4 carriers. Furthermore, we found an increase in plasma levels of IL1β levels and in PKR (eukaryotic translation initiation factor 2 alpha kinase 2) gene expression in isolated lymphocytes. Altogether, our results suggest that, in the continuum of Alzheimer's disease, people at risk of developing the disease go through different redox phases, from stablished reductive stress to oxidative stress.

Orthosiphon aristatus (Blume) Miq. Extracts attenuate Alzheimer-like pathology through anti-inflammatory, anti-oxidative, and β-amyloid inhibitory activities

ETHNOPHARMACOLOGICAL RELEVANCE

Orthosiphon aristatus (Blume) Miq. (OA) is a traditional folk-herb, which is usually used to treat acute and chronic nephritis, epilepsy, cystitis, and other diseases. Phenols and flavonoids are the main active compound compounds of OA, with proven anti-inflammatory and antioxidant activities.

AIMS OF THIS STUDY

Based on evidenced therapeutic activities, we aimed to investigate the impact of OA on Alzheimer's disease (AD) which is the most common age-related neurodegenerative disease, and the pathological features include accumulation of beta-amyloid (Aβ) and neurofibrillary tangles (NFT).

MATERIALS AND METHODS

OA was extracted with water, methanol, chloroform, and ethyl acetate, and determined its total flavonoid and phenolic contents. Initially, Aβ1-42 based cytotoxicity was induced in BV2 cells and C6 cells to investigate the therapeutic impact of OA therapy by MTT, RT-PCR, Western blot, and ELISA. Further, Aβ1-42 Oligomer (400 pmol)-induced AD mice model was established to evaluate the impact of OA extract on improving learning and memory impairment.

RESULTS

The results showed that the extract of OA could increase cell survival, inhibit the expression of TNF-α, IL-6, IL-1β, COX-2, and iNOS, and increase BDNF levels. We infer that the OA extract may attenuate Aβ-induced cytotoxicity by retarding the production of inflammatory-related factors. In the animal behavior test, the number of mice entering darkroom and the time of arriving at the platform were significantly reduced, indicating the learning and memory-improving ability of OA extract.

CONCLUSIONS

These findings imply that the OA ethanolic extract demonstrated an improving effect on memory and hence could serve as a potential therapeutic target for the treatment of neurodegenerative diseases like AD.

Lipid Peroxidation Drives Liquid-Liquid Phase Separation and Disrupts Raft Protein Partitioning in Biological Membranes

The peroxidation of membrane lipids by free radicals contributes to aging, numerous diseases, and ferroptosis, an iron-dependent form of cell death. Peroxidation changes the structure and physicochemical properties of lipids, leading to bilayer thinning, altered fluidity, and increased permeability of membranes in model systems. Whether and how lipid peroxidation impacts the lateral organization of proteins and lipids in biological membranes, however, remains poorly understood. Here, we employ cell-derived giant plasma membrane vesicles (GPMVs) as a model to investigate the impact of lipid peroxidation on ordered membrane domains, often termed membrane rafts. We show that lipid peroxidation induced by the Fenton reaction dramatically enhances the phase separation propensity of GPMVs into coexisting liquid-ordered (Lo) and liquid-disordered (Ld) domains and increases the relative abundance of the disordered phase. Peroxidation also leads to preferential accumulation of peroxidized lipids and 4-hydroxynonenal (4-HNE) adducts in the disordered phase, decreased lipid packing in both Lo and Ld domains, and translocation of multiple classes of raft proteins out of ordered domains. These findings indicate that the peroxidation of plasma membrane lipids disturbs many aspects of membrane rafts, including their stability, abundance, packing, and protein and lipid composition. We propose that these disruptions contribute to the pathological consequences of lipid peroxidation during aging and disease and thus serve as potential targets for therapeutic intervention.

Oxidative stress in Alzheimer's disease: current knowledge of signaling pathways and therapeutics

Alzheimer's disease's pathophysiology is still a conundrum. Growing number of evidences have elucidated the involvement of oxidative stress in the pathology of AD rendering it a major target for therapeutic development. Reactive oxygen species (ROS) generated by altered mitochondrial function, dysregulated electron transport chain and other sources elevate aggregated Aβ and neurofibrillary tangles which further stimulating the production of ROS. Oxidative stress induced damage to lipids, proteins and DNA result in neuronal death which leads to AD. In addition, oxidative stress induces apoptosis that is triggered by the modulation of ERK1/2 and Nrf2 pathway followed by increased GSK-3β expression and decreased PP2A activity. Oxidative stress exaggerates disease condition by interfering with various signaling pathways like RCAN1, CREB/ERK, Nrf2, PP2A, NFκB and PI3K/Akt. Studies have reported the role of TNF-α in oxidative stress stimulation that has been regulated by drugs like etanercept increasing the level of anti-oxidants. Other drugs like pramipexole, memantine, carvedilol, and melatonin have been reported to activate CREB/RCAN1 and Nrf2 pathways. In line with this, epigallocatechin gallate and genistein also target Nrf2 and CREB pathway leading to activation of downstream pathways like ARE and Keap1 which ameliorate oxidative stress condition. Donepezil and resveratrol reduce oxidative stress and activate AMPK pathway along with PP2A activation thus promoting tau dephosphorylation and neuronal survival. This study describes in detail the role of oxidative stress in AD, major signaling pathways involving oxidative stress induced AD and drugs under development targeting these pathways which may aid in therapeutic advances for AD.

Oxidative damage in neurodegeneration: roles in the pathogenesis and progression of Alzheimer disease

Alzheimer disease (AD) is associated with multiple etiologies and pathological mechanisms, among which oxidative stress (OS) appears as a major determinant. Intriguingly, OS arises in various pathways regulating brain functions, and it seems to link different hypotheses and mechanisms of AD neuropathology with high fidelity. The brain is particularly vulnerable to oxidative damage, mainly because of its unique lipid composition, resulting in an amplified cascade of redox reactions that target several cellular components/functions ultimately leading to neurodegeneration. The present review highlights the "OS hypothesis of AD," including amyloid beta-peptide-associated mechanisms, the role of lipid and protein oxidation unraveled by redox proteomics, and the antioxidant strategies that have been investigated to modulate the progression of AD. Collected studies from our groups and others have contributed to unraveling the close relationships between perturbation of redox homeostasis in the brain and AD neuropathology by elucidating redox-regulated events potentially involved in both the pathogenesis and progression of AD. However, the complexity of AD pathological mechanisms requires an in-depth understanding of several major intracellular pathways affecting redox homeostasis and relevant for brain functions. This understanding is crucial to developing pharmacological strategies targeting OS-mediated toxicity that may potentially contribute to slow AD progression as well as improve the quality of life of persons with this severe dementing disorder.

Deeper insight into ferroptosis: association with Alzheimer's, Parkinson's disease, and brain tumors and their possible treatment by nanomaterials induced ferroptosis

Ferroptosis is an emerging and novel type of iron-dependent programmed cell death which is mainly caused by the excessive deposition of free intracellular iron in the brain cells. This deposited free iron exerts a ferroptosis pathway, resulting in lipid peroxidation (LiPr). There are mainly three ferroptosis pathways viz. iron metabolism-mediated cysteine/glutamate, and LiPr-mediated. Iron is required by the brain as a redox metal for several physiological activities. Due to the iron homeostasis balance disruption, the brain gets adversely affected which further causes neurodegenerative diseases (NDDs) like Parkinson's and Alzheimer's disease, strokes, and brain tumors like glioblastoma (GBS), and glioma. Nanotechnology has played an important role in the prevention and treatment of these NDDs. A synergistic effect of nanomaterials and ferroptosis could prove to be an effective and efficient approach in the field of nanomedicine. In the current review, the authors have highlighted all the latest research in the field of ferroptosis, specifically emphasizing on the role of major molecular key players and various mechanisms involved in the ferroptosis pathway. Moreover, here the authors have also addressed the correlation of ferroptosis with the pathophysiology of NDDs and theragnostic effect of ferroptosis and nanomaterials for the prevention and treatment of NDDs.

Ethyl caffeate attefnuates Aβ-induced toxicity in Caenorhabditis elegans AD models via the insulin/insulin-like growth factor-1 signaling pathway

The pathogenesis of Alzheimer's disease (AD), a multifactorial progressive neurodegenerative disease associated with aging, is unclear. Ethyl caffeate is a plant polyphenol that has been reported to have neuroprotective effects, but the mechanisms by which it acts are unclear. In this study, for the first time, we investigated the molecular mechanism of its anti-AD properties using the Caernorhabditis elegans model. The results of our experiments showed that ethyl caffeate delayed the paralysis symptoms of CL4176 to a different extent and reduced the exogenous 5-hydroxytryptophan-induced paralysis phenotype. Further studies revealed that ethyl caffeate lowered Aβ plaques and depressed the expression of Aβ monomers and oligomers, but did not influence the mRNA levels of Aβ. Moreover, it was able to bring paraquat-induced ROS levels down to near-standard conditions. Real-time quantitative PCR experiment showed a significant upregulation of the transcript abundance of daf-16, skn-1 and hsf-1, key factors associated with the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway (IIS), and their downstream genes sod-3, gst-4 and hsp-16.2. It was further shown that ethyl caffeate activated the translocation of DAF-16 and SKN-1 from the cytoplasm to the nucleus and enhanced the expression of sod-3::GFP, gst-4::GFP and hsp-16.2::GFP in transgenic nematodes. This meant that the protection against Aβ toxicity by ethyl caffeate may be partly through the IIS signaling pathway. In addition, ethyl caffeate suppressed the aggregation of polyglutamine proteins in AM141, which indicated a potential protective effect against neurodegenerative diseases based on abnormal folding and aggregation of amyloid proteins. Taken together, ethyl caffeate is expected to develop as a potential drug for the management of AD.

Lipid peroxidation drives liquid-liquid phase separation and disrupts raft protein partitioning in biological membranes

The peroxidation of membrane lipids by free radicals contributes to aging, numerous diseases, and ferroptosis, an iron-dependent form of cell death. Peroxidation changes the structure, conformation and physicochemical properties of lipids, leading to major membrane alterations including bilayer thinning, altered fluidity, and increased permeability. Whether and how lipid peroxidation impacts the lateral organization of proteins and lipids in biological membranes, however, remains poorly understood. Here, we employ cell-derived giant plasma membrane vesicles (GPMVs) as a model to investigate the impact of lipid peroxidation on ordered membrane domains, often termed membrane rafts. We show that lipid peroxidation induced by the Fenton reaction dramatically enhances phase separation propensity of GPMVs into co-existing liquid ordered (raft) and liquid disordered (non-raft) domains and increases the relative abundance of the disordered, non-raft phase. Peroxidation also leads to preferential accumulation of peroxidized lipids and 4-hydroxynonenal (4-HNE) adducts in the disordered phase, decreased lipid packing in both raft and non-raft domains, and translocation of multiple classes of proteins out of rafts. These findings indicate that peroxidation of plasma membrane lipids disturbs many aspects of membrane rafts, including their stability, abundance, packing, and protein and lipid composition. We propose that these disruptions contribute to the pathological consequences of lipid peroxidation during aging and disease, and thus serve as potential targets for therapeutic intervention.

Lipid Peroxidation and Antioxidant Protection

Lipid peroxidation (LP) is the most important type of oxidative-radical damage in biological systems, owing to its interplay with ferroptosis and to its role in secondary damage to other biomolecules, such as proteins. The chemistry of LP and its biological consequences are reviewed with focus on the kinetics of the various processes, which helps understand the mechanisms and efficacy of antioxidant strategies. The main types of antioxidants are discussed in terms of structure-activity rationalization, with focus on mechanism and kinetics, as well as on their potential role in modulating ferroptosis. Phenols, pyri(mi)dinols, antioxidants based on heavy chalcogens (Se and Te), diarylamines, ascorbate and others are addressed, along with the latest unconventional antioxidant strategies based on the double-sided role of the superoxide/hydroperoxyl radical system.

A Systematic Review of the Effects of Capsaicin on Alzheimer's Disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterised by cognitive impairment, and amyloid-β plaques and neurofibrillary tau tangles at neuropathology. Capsaicin is a spicy-tasting compound found in chili peppers, with anti-inflammatory, antioxidant, and possible neuroprotective properties. Capsaicin intake has been associated with greater cognitive function in humans, and attenuating aberrant tau hyperphosphorylation in a rat model of AD. This systematic review discusses the potential of capsaicin in improving AD pathology and symptoms. A systematic analysis was conducted on the effect of capsaicin on AD-associated molecular changes, cognitive and behaviour resulting in 11 studies employing rodents and/or cell cultures, which were appraised with the Cochrane Risk of Bias tool. Ten studies showed capsaicin attenuated tau deposition, apoptosis, and synaptic dysfunction; was only weakly effective on oxidative stress; and had conflicting effects on amyloid processing. Eight studies demonstrated improved spatial and working memory, learning, and emotional behaviours in rodents following capsaicin treatment. Overall, capsaicin showed promise in improving AD-associated molecular, cognitive, and behavioural changes in cellular and animal models, and further investigations are recommended to test the readily available bioactive, capsaicin, to treat AD.

Revisiting the intersection of microglial activation and neuroinflammation in Alzheimer's disease from the perspective of ferroptosis

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by chronic neuroinflammation with amyloid beta-protein deposition and hyperphosphorylated tau protein. The typical clinical manifestation of AD is progressive memory impairment, and AD is considered a multifactorial disease with various etiologies (genetic factors, aging, lifestyle, etc.) and complicated pathophysiological processes. Previous research identified that neuroinflammation and typical microglial activation are significant mechanisms underlying AD, resulting in dysfunction of the nervous system and progression of the disease. Ferroptosis is a novel modality involved in this process. As an iron-dependent form of cell death, ferroptosis, characterized by iron accumulation, lipid peroxidation, and irreversible plasma membrane disruption, promotes AD by accelerating neuronal dysfunction and abnormal microglial activation. In this case, disturbances in brain iron homeostasis and neuronal ferroptosis aggravate neuroinflammation and lead to the abnormal activation of microglia. Abnormally activated microglia release various pro-inflammatory factors that aggravate the dysregulation of iron homeostasis and neuroinflammation, forming a vicious cycle. In this review, we first introduce ferroptosis, microglia, AD, and their relationship. Second, we discuss the nonnegligible role of ferroptosis in the abnormal microglial activation involved in the chronic neuroinflammation of AD to provide new ideas for the identification of potential therapeutic targets for AD.

Effects of Soybean Trypsin Inhibitor on Pancreatic Oxidative Damage of Mice at Different Growth Periods

The bioactive components in soybeans have significant physiological functions. However, the intake of soybean trypsin inhibitor (STI) may cause metabolic disorders. To investigate the effect of STI intake on pancreatic injury and its mechanism of action, a five-week animal experiment was conducted, meanwhile, a weekly monitor on the degree of oxidation and antioxidant indexes in the serum and pancreas of the animals was carried out. The results showed that the intake of STI had irreversible damage to the pancreas, according to the analysis of the histological section. Malondialdehyde (MDA) in the pancreatic mitochondria of Group STI increased significantly and reached a maximum (15.7 nmol/mg prot) in the third week. Meanwhile, the antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), trypsin (TPS), and somatostatin (SST) were decreased and reached minimum values (10 U/mg prot, 87 U/mg prot, 2.1 U/mg prot, 10 pg/mg prot) compared with the Group Control. The RT-PCR results of the expression of SOD, GSH-Px, TPS, and SST genes were consistent with the above. This study demonstrates that STI causes oxidative structural damage and pancreatic dysfunction by inducing oxidative stress in the pancreas, which could increase with time.

Advanced Overview of Biomarkers and Techniques for Early Diagnosis of Alzheimer's Disease

The development of early non-invasive diagnosis methods and identification of novel biomarkers are necessary for managing Alzheimer's disease (AD) and facilitating effective prognosis and treatment. AD has multi-factorial nature and involves complex molecular mechanism, which causes neuronal degeneration. The primary challenges in early AD detection include patient heterogeneity and lack of precise diagnosis at the preclinical stage. Several cerebrospinal fluid (CSF) and blood biomarkers have been proposed to show excellent diagnosis ability by identifying tau pathology and cerebral amyloid beta (Aβ) for AD. Intense research endeavors are being made to develop ultrasensitive detection techniques and find potent biomarkers for early AD diagnosis. To mitigate AD worldwide, understanding various CSF biomarkers, blood biomarkers, and techniques that can be used for early diagnosis is imperative. This review attempts to provide information regarding AD pathophysiology, genetic and non-genetic factors associated with AD, several potential blood and CSF biomarkers, like neurofilament light, neurogranin, Aβ, and tau, along with biomarkers under development for AD detection. Besides, numerous techniques, such as neuroimaging, spectroscopic techniques, biosensors, and neuroproteomics, which are being explored to aid early AD detection, have been discussed. The insights thus gained would help in finding potential biomarkers and suitable techniques for the accurate diagnosis of early AD before cognitive dysfunction.

Comparison of In Vitro Estrogenic Activity of Polygoni multiflori Radix and Cynanchi wilfordii Radix via the Enhancement of ERα/β Expression in MCF7 Cells

Postmenopausal women experience several symptoms, including inflammation and a sharp rise in oxidative stress caused by estrogen deprivation. Although estrogen replacement therapy (ERT) is generally regarded as an effective treatment for menopause, it has been used less frequently due to some adverse effects and high costs. Therefore, there is an immediate need to develop an effective herbal-based treatment that is affordable for low-income populations. Acordingly, this study explored the estrogen-like properties of methanol extracts from Cynanchum wilfordii (CW) and Poligonum multiflorum (PM), two important medicinal plants in Republic of Korea, Japan, and China. Due to the similar names and morphologies of these two radixes, they are frequently confused in the marketplace. Our previous colleagues discriminated between these two plants. In this study, we investigated the estrogenic activity of PM and CW using several in vitro assays with their possible mechanism of action. First, their phytochemical contents, such as gallic acid, 2,3,5,4'-tetrahydroxystilbene-2-O-glucoside (TSG) and emodin, were quantified using high-performance liquid chromatography (HPLC). Secondly, estrogen-like activity was assessed utilizing the well-known E-screen test and gene expression analysis in estrogen receptor (ER)-positive MCF7 cells. ROS inhibition and anti-inflammatory effects were analyzed using HaCaT and Raw 264.7 cells, respectively. Our findings demonstrate that PM extracts significantly increased the expression of the estrogen-dependent genes (ERα, ERβ, pS2) and boosted MCF7 cell proliferation in comparison to CW extracts. Additionally, PM extract demonstrated a significant reduction in reactive oxygen species (ROS) production as well as an enhanced antioxidant profile compared to the CW extract. Further, the PM extract treatment significantly reduced the generation of nitric oxide (NO) in RAW 264.7 cells, a murine macrophage cell line, demonstrating the anti-inflammatory properties of the extract. Finally, this research offers an experimental foundation for the use of PM as a phytoestrogen to minimize menopausal symptoms.

Recent Overview of Potent Antioxidant Activity of Coordination Compounds

During recent decades, the complexation of organic ligands toward several metal ions of s-p and d-block has been applied as a plan to enhance its antioxidant performance. Due to their wide range of beneficial impacts, coordination compounds are widely used in industries, specifically in the medicinal and pharmaceutical fields. The activity is generally improved by chelation consequently knowing that the characteristics of both ligands and metals can lead to the development of greatly active compounds. Chelation compounds are a substitute for using the traditional synthetic antioxidants, because metal chelates present benefits, including a variety in geometry, oxidation states, and coordination number, that assist and favor the redox methods associated with antioxidant action. As well as understanding the best studied anti-oxidative assets of these compounds, coordination compounds are involved in the free radical scavenging process and protecting human organisms from the opposing effects of these radicals. The antioxidant ability can be assessed by various interrelated systems. The methodological modification offers the most knowledge on the antioxidant property of metal chelates. Colorimetric techniques are the most used, though electron paramagnetic resonance (EPR) is an alternative for metallic compounds, since color does not affect the results. Information about systems, with their benefits, and restrictions, permits a dependable valuation of the antioxidant performance of coordination compounds, as well as assisting application in various states wherever antioxidant drugs are required, such as in food protection, appropriate good-packaged foods, dietary supplements, and others. Because of the new exhaustive analysis of organic ligands, it has become a separate field of research in chemistry. The present investigation will be respected for providing a foundation for the antioxidant properties of organic ligands, future tests on organic ligands, and building high-quality antioxidative compounds.

Protective Actions of α-Tocopherol on Cell Membrane Lipids of Paraquat-Stressed Human Astrocytes Using Microarray Technology, MALDI-MS and Lipidomic Analysis

Cellular senescence is one of the main contributors to some neurodegenerative disorders. The early detection of senescent cells or their related effects is a key aspect in treating disease progression. In this functional deterioration, oxidative stress and lipid peroxidation play an important role. Endogenous antioxidant compounds, such as α-tocopherol (vitamin E), can mitigate these undesirable effects, particularly lipid peroxidation, by blocking the reaction between free radicals and unsaturated fatty acid. While the antioxidant actions of α-tocopherol have been studied in various systems, monitoring the specific effects on cell membrane lipids at scales compatible with large screenings has not yet been accomplished. Understanding the changes responsible for this protection against one of the consequences of senescence is therefore necessary. Thus, the goal of this study was to determinate the changes in the lipid environment of a Paraquat-treated human astrocytic cell line, as a cellular oxidative stress model, and the specific actions of the antioxidant, α-tocopherol, using cell membrane microarray technology, MALDI-MS and lipidomic analysis. The stress induced by Paraquat exposure significantly decreased cell viability and triggered membrane lipid changes, such as an increase in certain species of ceramides that are lipid mediators of apoptotic pathways. The pre-treatment of cells with α-tocopherol mitigated these effects, enhancing cell viability and modulating the lipid profile in Paraquat-treated astrocytes. These results demonstrate the lipid modulation effects of α-tocopherol against Paraquat-promoted oxidative stress and validate a novel analytical high-throughput method combining cell cultures, microarray technology, MALDI-MS and multivariate analysis to study antioxidant compounds against cellular senescence.

New Insights into the Gut Microbiota in Neurodegenerative Diseases from the Perspective of Redox Homeostasis

An imbalance between oxidants and antioxidants in the body can lead to oxidative stress, which is one of the major causes of neurodegenerative diseases. The gut microbiota contains trillions of beneficial bacteria that play an important role in maintaining redox homeostasis. In the last decade, the microbiota-gut-brain axis has emerged as a new field that has revolutionized the study of the pathology, diagnosis, and treatment of neurodegenerative diseases. Indeed, a growing number of studies have found that communication between the brain and the gut microbiota can be accomplished through the endocrine, immune, and nervous systems. Importantly, dysregulation of the gut microbiota has been strongly associated with the development of oxidative stress-mediated neurodegenerative diseases. Therefore, a deeper understanding of the relationship between the gut microbiota and redox homeostasis will help explain the pathogenesis of neurodegenerative diseases from a new perspective and provide a theoretical basis for proposing new therapeutic strategies for neurodegenerative diseases. In this review, we will describe the role of oxidative stress and the gut microbiota in neurodegenerative diseases and the underlying mechanisms by which the gut microbiota affects redox homeostasis in the brain, leading to neurodegenerative diseases. In addition, we will discuss the potential applications of maintaining redox homeostasis by modulating the gut microbiota to treat neurodegenerative diseases, which could open the door for new therapeutic approaches to combat neurodegenerative diseases.

Integrated chromatographic approach for the discovery of gingerol antioxidants from Dracocephalum heterophyllum and their potential targets

As a traditional Tibetan medicine, Dracocephalum heterophyllum has many benefits, but due to the complicated procedures of separation and purification of its chemical constituents, there are few reports on gingerols. In this study, four antioxidative gingerols were isolated from Dracocephalum heterophyllum by an integrated chromatographic approach. Antioxidant activity was then determined by in vitro experiments and its potential targets of action were investigated. First, the extract was pretreated using silica gel, MCI GEL®CHP20P, and diol and spherical medium pressure columns, while the antioxidant peaks were identified using an online HPLC-1,1-diphenyl-2-picrylhydrazyl system. Then, the antioxidant peaks were directionally separated and purified by high pressure liquid chromatography to obtain four gingerols with a purity higher than 95%, namely 5-methoxy-6-gingerol, 6-shogaol, 6-paradol, and diacetoxy-6-gingerdiol. Finally, 1,1-diphenyl-2-picrylhydrazyl assays and cellular antioxidant experiments were carried out, and molecular docking was used to explore potential antioxidant targets. The isolated gingerols upregulated the activity of antioxidant enzymes, including superoxide dismutase (SOD), heme oxygenase-1 (HO-1) and NADPH oxidase 2 (NOX2), while they had little effect on the activity of nadph:quinone oxidoreductase-1 (NQO1). This method can efficiently prepare and isolate antioxidative gingerols from Dracocephalum heterophyllum, and it can be extended to isolate antioxidants from other natural products.

Oxidative stress, the immune response, synaptic plasticity, and cognition in transgenic models of Alzheimer disease

INTRODUCTION

Worldwide, approximately 50 million people have dementia, with Alzheimer disease (AD) being the most common type, accounting for 60%-70% of cases. Given its high incidence, it is imperative to design studies to expand our knowledge about its onset and development, and to develop early diagnosis strategies and/or possible treatments. One methodological strategy is the use of transgenic mouse models for the study of the factors involved in AD aetiology, which include oxidative stress and the immune response.

DEVELOPMENT

We searched the PubMed, Scopus, and Google Scholar databases for original articles and reviews published between 2013 and 2019. In this review, we address two factors that have been studied independently, oxidative stress and the immune response, in transgenic models of AD, and discuss the relationship between these factors and their impact on the loss of synaptic and structural plasticity, resulting in cognitive impairment.

CONCLUSION

This review describes possible mechanisms by which oxidative stress and the immune response participate in the molecular, cellular, and behavioural effects of AD, observing a close relationship between these factors, which lead to cognitive impairment.

A Comprehensive Review on Beneficial Effects of Catechins on Secondary Mitochondrial Diseases

Mitochondria are the main sites for oxidative phosphorylation and synthesis of adenosine triphosphate in cells, and are known as cellular power factories. The phrase "secondary mitochondrial diseases" essentially refers to any abnormal mitochondrial function other than primary mitochondrial diseases, i.e., the process caused by the genes encoding the electron transport chain (ETC) proteins directly or impacting the production of the machinery needed for ETC. Mitochondrial diseases can cause adenosine triphosphate (ATP) synthesis disorder, an increase in oxygen free radicals, and intracellular redox imbalance. It can also induce apoptosis and, eventually, multi-system damage, which leads to neurodegenerative disease. The catechin compounds rich in tea have attracted much attention due to their effective antioxidant activity. Catechins, especially acetylated catechins such as epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), are able to protect mitochondria from reactive oxygen species. This review focuses on the role of catechins in regulating cell homeostasis, in which catechins act as a free radical scavenger and metal ion chelator, their protective mechanism on mitochondria, and the protective effect of catechins on mitochondrial deoxyribonucleic acid (DNA). This review highlights catechins and their effects on mitochondrial functional metabolic networks: regulating mitochondrial function and biogenesis, improving insulin resistance, regulating intracellular calcium homeostasis, and regulating epigenetic processes. Finally, the indirect beneficial effects of catechins on mitochondrial diseases are also illustrated by the warburg and the apoptosis effect. Some possible mechanisms are shown graphically. In addition, the bioavailability of catechins and peracetylated-catechins, free radical scavenging activity, mitochondrial activation ability of the high-molecular-weight polyphenol, and the mitochondrial activation factor were also discussed.

Zingiber officinale and Vernonia amygdalina Infusions Improve Redox Status in Rat Brain

The study investigated the effects of Zingiber officinale root and Vernonia amygdalina leaf on the brain redox status of Wistar rats. Twenty-four (24) rats weighing 160 ± 20 g were randomly assigned into four (4) groups, each with six (6) rats. Animals in Group 1 (control) were orally administered distilled water (1 mL), while the test groups were orally administered 5 mg/mL of either Z. officinale, V. amygdalina infusion, or a combination of both, respectively, for 7 days. The rats were sacrificed at the end of treatments and blood and tissue were harvested and prepared for biochemical assays. Results showed that administration of V. amygdalina and Z. officinale, as well as their coadministration, reduced the levels of malondialdehyde (MDA), nitric oxide (NO), acetylcholinesterase (AChE), and myeloperoxidase (MPO) in rat brain tissue compared with the control group. Conversely, coadministration of V. amygdalina and Z. officinale increased the levels of reduced glutathione (GSH) in rat brain tissue compared with the control group. However, the administration of the infusions singly, as well as the combination of both infusions, did not have any effect on the rat brain levels of glutathione peroxidase (GPx) and catalase (CAT) antioxidant enzymes compared to the control. Taken together, the findings indicate that the V. amygdalina and Z. officinale tea infusions have favorable antioxidant properties in the rat brain. The findings are confirmatory and contribute to deepening our understanding of the health-promoting effects of V. amygdalina and Z. officinale tea infusions.

Synthesis and application of phosphorylated saccharides in researching carbohydrate-based drugs

Phosphorylated saccharides are valuable targets in glycochemistry and glycobiology, which play an important role in various physiological and pathological processes. The current research on phosphorylated saccharides primarily focuses on small molecule inhibitors, glycoconjugate vaccines and novel anti-tumour targeted drug carrier materials. It can maximise the pharmacological effects and reduce the toxicity risk caused by nonspecific off-target reactions of drug molecules. However, the number and types of natural phosphorylated saccharides are limited, and the complexity and heterogeneity of their structures after extraction and separation seriously restrict their applications in pharmaceutical development. The increasing demands for the research on these molecules have extensively promoted the development of carbohydrate synthesis. Numerous innovative synthetic methodologies have been reported regarding the continuous expansion of the potential building blocks, catalysts, and phosphorylation reagents. This review summarizes the latest methods for enzymatic and chemical synthesis of phosphorylated saccharides, emphasizing their breakthroughs in yield, reactivity, regioselectivity, and application scope. Additionally, the anti-bacterial, anti-tumour, immunoregulatory and other biological activities of some phosphorylated saccharides and their applications were also reviewed. Their structure-activity relationship and mechanism of action were discussed and the key phosphorylation characteristics, sites and extents responsible for observed biological activities were emphasised. This paper will provide a reference for the application of phosphorylated saccharide in the research of carbohydrate-based drugs in the future.

Clinical implications of lipid peroxides levels in plasma and tumor tissue in breast cancer patients

Oxidative stress can promote the oxidation of lipoproteins and polyunsaturated fatty acids present in cell membranes; an event known as lipid peroxidation (LPO). LPO has been associated with carcinogenesis and cancer progression, however, its meaning concerning the clinicopathological aspects of human breast cancer is not clear. This study investigated LPO profiles in tumor and plasma samples from breast cancer patients (n = 140) considering their clinicopathological features (age at diagnosis, menopausal status, body mass index, tumor histological grade, tumor size, ki-67 proliferation index, presence of metastasis, chemotherapy response, the molecular subtype of cancer and overall survival status). LPO levels were estimated by tert-butyl hydroperoxide-initiated chemiluminescence. High LPO levels were found regarding poor prognosis parameters as young age at diagnosis (p = 0.006 in tissue), premenopausal patients (p = 0.012 in tissue), high-grade tumors (p = 0.010 in tissue and p = 0.002 in plasma), metastatic disease (p = 0.046 in tissue), chemoresistant tumors (p = 0.041 in tissue), disease relapse (p = 0.018 in tissue and p = 0.009 in plasma) and overall survival status (p = 0.001 in plasma). Our findings point out the clinical meaning of LPO and highlight it as an oxidative stress event linked to poor prognosis and disease aggressiveness in breast cancer patients.

Investigation of coenzyme Q10 status, serum amyloid-β, and tau protein in patients with dementia

Objectives

Dementia is an oxidative stress-related disease. Coenzyme Q10 is a nutrient that occurs naturally in the human body and acts as an antioxidant. The purpose of this study was to investigate the relationships of coenzyme Q10 status, biomarkers for dementia (amyloid β and tau protein), and antioxidant capacity in patients with dementia.

Methods

Eighty dementia patients aged ≥60 years and with a mini mental state examination (MMSE) score ≤ 26 were enrolled. The levels of coenzyme Q10, total antioxidant capacity (TAC), amyloid β, and tau protein were measured.

Results

A total of 73% of patients had a low coenzyme Q10 status. Patients with low coenzyme Q10 status had a significantly higher level of serum amyloid β-42 and amyloid β-42/40 ratio (p < 0.05). Coenzyme Q10 status was significantly correlated with the values of TAC, MMSE score, amyloid β-42, and amyloid β-42/40 ratio (p < 0.05) but not with tau protein. Additionally, a high proportion of moderate dementia patients were found to have low coenzyme Q10 status (p = 0.07).

Conclusion

Patients with dementia suffered from coenzyme Q10 deficiency, and the degree of deficiency was related to the level of amyloid-β and antioxidant capacity. Since adequate level of coenzyme Q10 may delay the progression of dementia, monitoring coenzyme Q10 status in patients with dementia is necessary.

The Prophylactic and Multimodal Activity of Two Isatin Thiosemicarbazones against Alzheimer's Disease In Vitro

Alzheimer’s disease (AD) is a multifactorial disorder strongly involving the formation of amyloid-β (Aβ) oligomers, which subsequently aggregate into the disease characteristic insoluble amyloid plaques, in addition to oxidative stress, inflammation and increased acetylcholinesterase activity. Moreover, Aβ oligomers interfere with the expression and activity of Glycogen synthase kinase-3 (GSK3) and Protein kinase B (PKB), also known as AKT. In the present study, the potential multimodal effect of two synthetic isatin thiosemicarbazones (ITSCs), which have been previously shown to prevent Aβ aggregation was evaluated. Both compounds resulted in fully reversing the Aβ-mediated toxicity in SK-NS-H cells treated with exogenous Aβ peptides at various pre-incubation time points and at 1 μM. Cell survival was not recovered when compounds were applied after Aβ cell treatment. The ITSCs were non-toxic against wild type and 5xFAD primary hippocampal cells. They reversed the inhibition of Akt and GSK-3β phosphorylation in 5xFAD cells. Finally, they exhibited good antioxidant potential and moderate lipoxygenase and acetylcholinesterase inhibition activity. Overall, these results suggest that isatin thiosemicarbazone is a suitable scaffold for the development of multimodal anti-AD agents.

Altered Metabolism in Alzheimer Disease Brain: Role of Oxidative Stress

Significance: Alzheimer disease (AD) is an all-too-common condition in the aging population. However, aging does not automatically equal neurodegeneration and memory decline. Recent Advances: This review article involves metabolic changes in the AD brain that are related to oxidative stress. Selected pathways are identified as potential targets for intervention in AD. Critical Issues: One of the main factors of AD is the oxidative imbalance within the central nervous system, causing a disruption in metabolic processes. Reactive oxygen species (ROS) are a natural consequence of many cellular processes, especially those associated with mitochondria, such as the electron transport chain. Some ROS, when kept under control and maintained at reasonable levels, often play roles in cell signaling. The cellular damage of ROS arises when oxidative imbalance occurs, in which case ROS are not controlled, leading to a myriad of alterations in cellular metabolic processes. These altered pathways include, among others, dysfunctional glycolysis, calcium regulation, lipid metabolism, mitochondrial processes, and mammalian target of rapamycin pathway dysregulation. Future Directions: Understanding how ROS can lead to these alterations can, ideally, elucidate therapeutic options for retarding AD progression in the aging population. Antioxid. Redox Signal. 36, 1289-1305.

Functional Deficits of 5×FAD Neural Stem Cells Are Ameliorated by Glutathione Peroxidase 4

Alzheimer's disease (AD) is the most common cause of dementia affecting millions of people around the globe. Impaired neurogenesis is reported in AD as well as in AD animal models, although the underlying mechanism remains unclear. Elevated lipid peroxidation products are well-documented in AD. In current study, the role of lipid peroxidation on neural stem cell (NSCs) function is tested. Neural stem cells (NSCs) from 5×FAD mice, a widely used AD model with impaired neurogenesis, were observed to have increased levels of lipid reactive oxygen species compared to NSCs from control WT mice. 5×FAD NSCs exhibited altered differentiation potential as revealed by their propensity to differentiate into astrocytic lineage instead of neuronal lineage compared to WT NSCs. In addition, 5×FAD NSCs showed a reduced level of Gpx4, a key enzyme in reducing hydroperoxides in membrane lipids, and this reduction appeared to be caused by enhanced autophagy-lysosomal degradation of Gpx4 protein. To test if increasing Gpx4 could restore differentiation potential, NSCs from 5×FAD and Gpx4 double transgenic mice, i.e., 5×FAD/GPX4 mice were studied. Remarkably, upon differentiation, neuronal linage cells increased significantly in 5×FAD/GPX4 cultures compared to 5×FAD cultures. Taken together, the findings suggest that deficiency of lipid peroxidation defense contributes to functional decline of NSCs in AD.

PPAR-α Agonist GW7647 Protects Against Oxidative Stress and Iron Deposit via GPx4 in a Transgenic Mouse Model of Alzheimer's Diseases

Alzheimer's disease (AD) is a neurodegenerative disease caused by lipid peroxidation and iron hemostasis of the brain. PPAR-α is regarded as the most encouraging therapeutic approach of several neurodegenerative and metabolic disorders, due to its potent regulatory effects. In this study, we examined the ameliorative effect and the mechanisms of a PPAR-α agonist, GW7647, on the established AD models using APP/PS1 mice and APPsw/SH-SY5Y cells. Through Aβ quantification and behavioral test, we found that GW7647 reduced Aβ burden and improved cognitive defect in APP/PS1 mice. Liquid chromatography-mass spectrometry analysis indicated that GW7647 could enter the brain after oral administration. Neuronal cell death and iron deposit were inhibited, accompanied by decreased lipid peroxidation and inflammation. In an in vitro study of APPsw cells, we found that PPAR-α directly bound with GPx4 intron3 to promote GPx4 transcription and reduced the iron transport capability. Our data suggested that activation of PPAR-α by GW7647 improved the disruption of iron homeostasis in the brain of APP/PS1 mice and alleviated neuronal inflammation and lipid peroxidation, which was possibly related to the upregulated transcription of GPx4 mediated by the interaction of GPx4 noncoding region and the PPAR-α.

Oxidative stress, the immune response, synaptic plasticity, and cognition in transgenic models of Alzheimer disease

INTRODUCTION

Worldwide, approximately 50 million people have dementia, with Alzheimer disease (AD) being the most common type, accounting for 60%-70% of cases. Given its high incidence, it is imperative to design studies to expand our knowledge about its onset and development, and to develop early diagnosis strategies and/or possible treatments. One methodological strategy is the use of transgenic mouse models for the study of the factors involved in AD aetiology, which include oxidative stress and the immune response.

DEVELOPMENT

We searched the PubMed, Scopus, and Google Scholar databases for original articles and reviews published between 2013 and 2019. In this review, we address 2 factors that have been studied independently, oxidative stress and the immune response, in transgenic models of AD, and discuss the relationship between these factors and their impact on the loss of synaptic and structural plasticity, resulting in cognitive impairment.

CONCLUSION

This review describes possible mechanisms by which oxidative stress and the immune response participate in the molecular, cellular, and behavioural effects of AD, observing a close relationship between these factors, which lead to cognitive impairment.

Ferroptosis, a Potential Therapeutic Target in Alzheimer's Disease

Cell death is a common phenomenon in the progression of Alzheimer’s disease (AD). However, the mechanism of triggering the death of neuronal cells remains unclear. Ferroptosis is an iron-dependent lipid peroxidation-driven cell death and emerging evidences have demonstrated the involvement of ferroptosis in the pathological process of AD. Moreover, several hallmarks of AD pathogenesis were consistent with the characteristics of ferroptosis, such as excess iron accumulation, elevated lipid peroxides, and reactive oxygen species (ROS), reduced glutathione (GSH), and glutathione peroxidase 4 (GPX4) levels. Besides, some ferroptosis inhibitors can relieve AD-related pathological symptoms in AD mice and exhibit potential clinical benefits in AD patients. Therefore, ferroptosis is gradually being considered as a distinct cell death mechanism in the pathogenesis of AD. However, direct evidence is still lacking. In this review, we summarize the features of ferroptosis in AD, its underlying mechanisms in AD pathology, and review the application of ferroptosis inhibitors in both AD clinical trials and mice/cell models, to provide valuable information for future treatment and prevention of this devastating disease.

From Menopause to Neurodegeneration-Molecular Basis and Potential Therapy

The impacts of menopause on neurodegenerative diseases, especially the changes in steroid hormones, have been well described in cell models, animal models, and humans. However, the therapeutic effects of hormone replacement therapy on postmenopausal women with neurodegenerative diseases remain controversial. The steroid hormones, steroid hormone receptors, and downstream signal pathways in the brain change with aging and contribute to disease progression. Estrogen and progesterone are two steroid hormones which decline in circulation and the brain during menopause. Insulin-like growth factor 1 (IGF-1), which plays an import role in neuroprotection, is rapidly decreased in serum after menopause. Here, we summarize the actions of estrogen, progesterone, and IGF-1 and their signaling pathways in the brain. Since the incidence of Alzheimer’s disease (AD) is higher in women than in men, the associations of steroid hormone changes and AD are emphasized. The signaling pathways and cellular mechanisms for how steroid hormones and IGF-1 provide neuroprotection are also addressed. Finally, the molecular mechanisms of potential estrogen modulation on N-methyl-d-aspartic acid receptors (NMDARs) are also addressed. We provide the viewpoint of why hormone therapy has inconclusive results based on signaling pathways considering their complex response to aging and hormone treatments. Nonetheless, while diagnosable AD may not be treatable by hormone therapy, its preceding stage of mild cognitive impairment may very well be treatable by hormone therapy.

Phosphorylation of polysaccharides: A review on the synthesis and bioactivities

Polysaccharides are macromolecules obtained from a wide range of sources and are known to have diverse biological activities. The biological activities of polysaccharides depend on their structure and physicochemical properties, including water solubility, monosaccharide composition, degree of branching, molecular structure, and molecular weight. Phosphorylation is a commonly used chemical modification method that improves the physicochemical properties of native polysaccharides, thus enhancing their biological activity, or even imparting novel biological activity. Therefore, phosphorylated polysaccharides have attracted increasing attention owing to their antioxidant, antitumor, antiviral, immunomodulatory, and hepatoprotective effects. In this review, we have discussed recent advances in the phosphorylation of polysaccharides, and the methods used for phosphorylation, structural characterization, and determination of biological activities, to provide a theoretical basis for the use of polysaccharides. The structure-activity relationship of phosphorylated polysaccharides and their use in the food and pharmaceutical industries needs to be further studied.

Nutrigenomics of Dietary Lipids

Dietary lipids have a major role in nutrition, not only for their fuel value, but also as essential and bioactive nutrients. This narrative review aims to describe the current evidence on nutrigenomic effects of dietary lipids. Firstly, the different chemical and biological properties of fatty acids contained both in plant- and animal-based food are illustrated. A description of lipid bioavailability, bioaccessibility, and lipotoxicity is provided, together with an overview of the modulatory role of lipids as pro- or anti-inflammatory agents. Current findings concerning the metabolic impact of lipids on gene expression, epigenome, and gut microbiome in animal and human studies are summarized. Finally, the effect of the individual’s genetic make-up on lipid metabolism is described. The main goal is to provide an overview about the interaction between dietary lipids and the genome, by identifying and discussing recent scientific evidence, recognizing strengths and weaknesses, to address future investigations and fill the gaps in the current knowledge on metabolic impact of dietary fats on health.

Mechanistic Biomarkers in Toxicology

Biomarkers are important parameters that are reliable, applicable, reproducible, and generally inexpensive. All biomarkers have a significant role in human health, especially mechanistic biomarkers, which are the most important for the prevention of toxic effects and diseases. They demonstrate the possibility of diagnosis, prognosis, recurrence, and spread of disease. Furthermore, they show the exposure levels to numerous chemical, biological, and physical agents. To date, the development and application of biomarkers require the knowledge of mechanisms underlying their production. Therefore, the present study focused on the possible mechanistic biomarkers.

Chinese bayberry Jiaosu fermentation – changes of mycobiota composition and antioxidant properties

The aim of the study was to investigate the dynamic changes of mycobiota community, and the resultant effects on the antioxidant properties during the Chinese bayberry Jiaosu fermentation. The structure and composition of mycobiota during the Chinese bayberry Jiaosu fermentation were significantly changed (p < 0.001) and clearly clustered into two distinct phases (Phase 1: Day 5–20; Phase 2: Day 30–60, p < 0.001). From Phase 1 to Phase 2, the dominant fungi gradually changed from Saccharomycetales fam Incertae sedis to Saccharomyces cerevisiae. The antioxidative properties (total polyphenols, 1,1-diphenyl-2-picrylhydrazyl [DPPH], superoxide and 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulphonate) [ABTS] radical scavenging) of Chinese bayberry Jiaosu were significantly increased by 250.4, 73.9, 25.3 and 40.0% respectively (p < 0.001). Co-occurrence network analysis revealed that Saccharomyces cerevisiae contributed to the increase of antioxidative properties in the Chinese bayberry Jiaosu fermentation. Our research indicates that fermentation into Chinese bayberry Jiaosu is an effective and new method for high-valued utilization of Chinese bayberry.

Antioxidant Effect of Soymilk Fermented by Lactobacillus plantarum HFY01 on D-Galactose-Induced Premature Aging Mouse Model

The antioxidant effect of soymilk fermented by Lactobacillus plantarum HFY01 (screened from yak yogurt) was investigated on mice with premature aging induced by D-galactose. In vitro antioxidant results showed that L. plantarum HFY01-fermented soymilk (LP-HFY01-DR) had better ability to scavenge the free radicals 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) than unfermented soymilk and Lactobacillus bulgaricus-fermented soymilk. Histopathological observation showed that LP-HFY01-DR could protect the skin, spleen and liver, reduce oxidative damage and inflammation. Biochemical results showed that LP-HFY01-DR could effectively upregulate glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) levels and decrease malondialdehyde (MDA) content in the liver, brain, and serum. Real-time quantitative reverse transcription polymerase chain reaction further showed that LP-HFY01-DR could promote the relative expression levels of the genes encoding for cuprozinc superoxide dismutase (Cu/Zn-SOD, SOD1), manganese superoxide dismutase (Mn-SOD, SOD2), CAT, GSH, and GSH-Px in the liver, spleen, and skin. High-performance liquid chromatography results revealed daidzin, glycitin, genistin, daidzein, glycitein, and genistein in LP-HFY01-DR. In conclusion, LP-HFY01-DR could improve the antioxidant capacity in mice with premature aging induced by D-galactose.