Management of oxidative stress and other pathologies in Alzheimer’s disease

Policosanol protects against Alzheimer's disease-associated spatial cognitive decline in male rats: possible involved mechanisms

RATIONALE

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by cognitive decline and synaptic failure.

OBJECTIVE

The present study was designed to explore the possible protective effects of policosanol (PCO) on spatial cognitive capacity, long-term potentiation (LTP) induction, oxidant/antioxidant status, and Aβ plaques formation in an AD rat model induced by intracerebroventricular (ICV) injection of Aβ_1-40.

METHODS

Healthy adult male Wistar rats were randomly divided into control, sham (ICV injection of 5 µl phosphate-buffered saline), AG (50 mg/kg; P.O., as PCO vehicle), PCO (50 mg/kg; P.O.), AD model (ICV injection of 5 µl Aβ), AD + AG (50 mg/kg; P.O.), and AD + PCO (50 mg/kg; P.O.). Treatments were performed for eight consecutive weeks. At the end of the treatment course, spatial learning and memory functions, hippocampal long-term potentiation (LTP) induction, malondialdehyde (MDA), and total thiol group (TTG) levels, as well as the formation of Aβ plaques, were examined.

RESULTS

The results showed that injection of Aβ reduced spatial learning and memory abilities in the Barnes maze test, which was accompanied by decreases in field excitatory postsynaptic potential (fEPSP) slope, population spike (PS) amplitude, and TTG level and increases in Aβ plaque accumulation and MDA content. In contrast, PCO treatment improved all the above-mentioned changes in the Aβ-infused rats.

CONCLUSIONS

The results suggest that amelioration of hippocampal synaptic plasticity impairment, modulation of oxidant/antioxidant status, and inhibition of Aβ plaque formation by PCO may be the mechanisms behind its protective effect against AD-associated spatial cognitive decline.

Dendrimers in Alzheimer’s Disease: Recent Approaches in Multi-Targeting Strategies

Nanomaterials play an increasingly important role in current medicinal practice. As one of the most significant causes of human mortality, and one that is increasing year by year, Alzheimer’s disease (AD) has been the subject of a very great body of research and is an area in which nanomedicinal approaches show great promise. Dendrimers are a class of multivalent nanomaterials which can accommodate a wide range of modifications that enable them to be used as drug delivery systems. By means of suitable design, they can incorporate multiple functionalities to enable transport across the blood–brain barrier and subsequently target the diseased areas of the brain. In addition, a number of dendrimers by themselves often display therapeutic potential for AD. In this review, the various hypotheses relating to the development of AD and the proposed therapeutic interventions involving dendrimer–base systems are outlined. Special attention is focused on more recent results and on the importance of aspects such as oxidative stress, neuroinflammation and mitochondrial dysfunction in approaches to the design of new treatments.

Nature's Toolbox Against Tau Aggregation: An Updated Review of Current Research

Tau aggregation is a hallmark of several neurodegenerative disorders, such as Alzheimer's disease (AD), frontotemporal dementia, and progressive supranuclear palsy. Hyperphosphorylated tau is believed to contribute to the degeneration of neurons and the development of these complex diseases. Therefore, one potential treatment for these illnesses is to prevent or counteract tau aggregation. In recent years, interest has been increasing in developing nature-derived tau aggregation inhibitors as a potential treatment for neurodegenerative disorders. Researchers have become increasingly interested in natural compounds with multifunctional features, such as flavonoids, alkaloids, resveratrol, and curcumin, since these molecules can interact simultaneously with the various targets of AD. Recent studies have demonstrated that several natural compounds can inhibit tau aggregation and promote the disassembly of pre-formed tau aggregates. Nature-derived tau aggregation inhibitors hold promise as a potential treatment for neurodegenerative disorders. However, it is important to note that more research is needed to fully understand the mechanisms by which these compounds exert their effects and their safety and efficacy in preclinical and clinical studies. Nature-derived inhibitors of tau aggregation are a promising new direction in the research of neurodegenerative complexities. This review focuses on the natural products that have proven to be a rich supply for inhibitors in tau aggregation and their uses in neurodegenerative complexities, including AD.

Do Sleep Disturbances have a Dual Effect on Alzheimer's Disease?

Sleep disturbances and Alzheimer's disease have deleterious effects on various physiological and cognitive functions including synaptic plasticity, oxidative stress, neuroinflammation, and memory. In addition, clock genes expression is significantly altered following sleep disturbances, which may be involved in the pathogenesis of Alzheimer's disease. In this review article, we aimed to discuss the role of sleep disturbances and Alzheimer's disease in the regulation of synaptic plasticity, oxidative stress, neuroinflammation, and clock genes expression. Also, we aimed to find significant relationships between sleep disturbances and Alzheimer's disease in the modulation of these mechanisms. We referred to the controversial effects of sleep disturbances (particularly those related to the duration of sleep deprivation) on the modulation of synaptic function and neuroinflammation. We aimed to know that, do sleep disturbances have a dual effect on the progression of Alzheimer's disease? Although numerous studies have discussed the association between sleep disturbances and Alzheimer's disease, the new point of this study was to focus on the controversial effects of sleep disturbances on different biological functions, and to evaluate the potential dualistic role of sleep disturbances in the pathogenesis of Alzheimer's disease.

Neuroprotective Potentials of Flavonoids: Experimental Studies and Mechanisms of Action

Neurological and neurodegenerative diseases, particularly those related to aging, are on the rise, but drug therapies are rarely curative. Functional disorders and the organic degeneration of nervous tissue often have complex causes, in which phenomena of oxidative stress, inflammation and cytotoxicity are intertwined. For these reasons, the search for natural substances that can slow down or counteract these pathologies has increased rapidly over the last two decades. In this paper, studies on the neuroprotective effects of flavonoids (especially the two most widely used, hesperidin and quercetin) on animal models of depression, neurotoxicity, Alzheimer's disease (AD) and Parkinson's disease are reviewed. The literature on these topics amounts to a few hundred publications on in vitro and in vivo models (notably in rodents) and provides us with a very detailed picture of the action mechanisms and targets of these substances. These include the decrease in enzymes that produce reactive oxygen and ferroptosis, the inhibition of mono-amine oxidases, the stimulation of the Nrf2/ARE system, the induction of brain-derived neurotrophic factor production and, in the case of AD, the prevention of amyloid-beta aggregation. The inhibition of neuroinflammatory processes has been documented as a decrease in cytokine formation (mainly TNF-alpha and IL-1beta) by microglia and astrocytes, by modulating a number of regulatory proteins such as Nf-kB and NLRP3/inflammasome. Although clinical trials on humans are still scarce, preclinical studies allow us to consider hesperidin, quercetin, and other flavonoids as very interesting and safe dietary molecules to be further investigated as complementary treatments in order to prevent neurodegenerative diseases or to moderate their deleterious effects.

A Review of the Role of Curcumin in Metal Induced Toxicity

Metal toxicity poses a potential global threat to the environment and living beings. Their numerous agricultural, medical, industrial, domestic, and technological applications result in widespread distribution in the environment which raises concern on the potential effects of metals in terms of health hazards and environmental pollution. Chelation therapy has been the preferred medical treatment for metal poisoning. The chelating agent bounds metal ions to form complex cyclic structures known as 'chelates' to intensify their excretion from the body. The main disadvantage of synthetic chelators is that the chelation process removes vital nutrients along with toxic metals. Natural compounds are widely available, economical, and have minimal adverse effects compared to classical chelators. Herbal preparations can bind to the metal, reduce its absorption in the intestines, and facilitate excretion from the body. Curcumin, a bioactive substance in turmeric, is widely used as a dietary supplement. Most studies have shown that curcumin protects against metal-induced lipid peroxidation and mitigates adverse effects on the antioxidant system. This review article provides an analysis to show that curcumin imparts promising metal toxicity-ameliorative effects that are related to its intrinsic antioxidant activity.

Real-Time Detection and Visualization of Amyloid-β Aggregates Induced by Hydrogen Peroxide in Cell and Mouse Models of Alzheimer's Disease

Oxidative stress, caused by an imbalance between the production and the accumulation of reactive oxygen species (ROS), is a prominent cause of the neurotoxicity induced by aggregated amyloid-β (Aβ) in Alzheimer's disease (AD). Tools that can directly detect and monitor the presence and amount of Aβ-induced ROS are still lacking. We report herein the first Aβ-targeted ratiometric H₂O₂-responsive fluorescent probe for real-time detection and monitoring of the Aβ-induced H₂O₂ level in cell and AD mouse models. The H₂O₂-responsive probe is constructed based on a methylamino-substituted quinolinium-based cyanine as the fluorescence moiety and a phenylboronate ester as the sensing reaction site. This sensing probe exhibits a large emission wavelength shift of ∼87 nm upon reacting with H₂O₂, a high binding selectivity for Aβ, and a faster response toward H₂O₂ in the presence of Aβ, concomitant with an enhanced fluorescence intensity, hence greatly boosting the sensitivity of in-situ H₂O₂ detection. This biocompatible and nontoxic probe is capable of ratiometrically detecting and imaging endogenous H₂O₂ induced by Aβ in a neuronal cell model. Remarkably, this Aβ-targeted H₂O₂-responsive probe is also able to detect, monitor, and differentiate different Aβ-induced H₂O₂ levels in real time in different age groups of transgenic AD mice in which the cerebral H₂O₂ level increases age dependently concomitant with the plaque contents. Therefore, this smart probe can act as a powerful tool to diagnose high-risk subjects and diseased brains of AD and to further study the role of ROS in AD pathology.

Stem Cells and Natural Agents in the Management of Neurodegenerative Diseases: A New Approach

Neurodegenerative diseases refer to a group of neurological disorders as a consequence of various destructive illnesses, that predominantly impact neurons in the central nervous system, resulting in impairments in certain brain functions. Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, and other neurodegenerative disorders represent a major risk to human health. In order to optimize structural and functional recovery, reconstructive methods integrate many approaches now, to address the complex and multivariate pathophysiology of neurodegenerative disorders. Stem cells, with their unique property of regeneration, offer new possibilities in regenerative and reconstructive medicine. Concurrently, there is an important role for natural products in controlling many health sufferings and they can delay or even prevent the onset of various diseases. In addition, due to their therapeutic properties, they have been used as neuroprotective agents to treat neurodegenerative disorders. After decades of intensive research, scientists made advances in treating these disorders so far, but current therapies are still not capable of preventing the illnesses from progressing. Therefore, in this review, we focused on a new perspective combining stem cells and natural products as an innovative therapy option in the management of neurodegenerative diseases.

Effects of Sub-chronic Lead Exposure on Essential Element Levels in Mice

Lead (Pb), a corrosion-resistant heavy non-ferrous metal, is one of the most common environmental neurotoxic metals. The effects of Pb on other essential metal elements are contradictory. Therefore, this in vivo study addressed the effects of sub-chronic Pb exposure on the distribution of other divalent metals, exploring the relationships between Pb levels in blood, teeth, bones, hair, and brain tissues. Thirty-two healthy male C57BL/6 mice received intragastric administration (i.g.) with 0, 12.5, 25, and 50 mg/kg Pb acetate, once a day for 8 weeks. Levels of Pb and other metal elements [including iron(Fe), zinc (Zn), magnesium (Mg), copper (Cu), and calcium(Ca)] in the whole blood, teeth, the right thighbone, hair, and brain tissues (including cortex, hippocampus, striatum, and hypothalamus) were detected with inductively coupled plasma-mass spectrometry (ICP-MS). Pb levels in all detected organs were increased after Pb-exposed for 8 weeks. The results of relationship analysis between Pb levels in the tissues and lifetime cumulative Pb exposure (LCPE) showed that Pb levels in the blood, bone, and hair could indirectly reflect the Pb accumulation in the murine brain. These measures might serve as valuable biomarkers for chronic Pb exposure reflective of the accumulation of Pb in the central nervous system (CNS). Sub-chronic Pb exposure for 8 weeks altered Ca, Cu, Fe, and Zn levels, but no effects were noted on Mg levels in any of the analyzed tissues. Pb decreased Ca in teeth, Cu in thighbone and teeth, Zn in whole blood and hair, and Fe in hair. In contrast, Pb increased Ca levels in corpus striatum and hypothalamus, Cu levels in striatum, Zn levels in teeth, and Fe levels in hippocampus, thighbone, and teeth. The Pb-induced changes in metal ratios in various tissues may serve as valuable biomarkers for chronic Pb exposure as they are closely related to the accumulations of Pb in the murine CNS. The results suggest that altered distribution of several essential metal elements may be involved in Pb-induced neurotoxicity. Additional studies should address the interaction between Pb and essential metal elements in the CNS and other organs.

Octadecaneuropeptide Ameliorates Cognitive Impairments Through Inhibiting Oxidative Stress in Alzheimer's Disease Models

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by amyloid-β peptide (Aβ) deposition. Aβ accumulation induces oxidative stress, leading to mitochondrial dysfunction, apoptosis, and so forth. Octadecaneuropeptide (ODN), a diazepam-binding inhibitor (DBI)-derived peptide, has been reported to have antioxidant properties. However, it is unclear whether ODN has neuroprotective effects in AD.

OBJECTIVE

To profile the potential effects of ODN on AD.

METHODS

We established a mouse model of AD via microinjection of Aβ in the lateral ventricle. Utilizing a combination of western blotting assays, electrophysiological recordings, and behavioral tests, we investigated the neuroprotective effects of ODN on AD.

RESULTS

DBI expression was decreased in AD model mice and cells. Meanwhile, ODN decreased Aβ generation by downregulating amyloidogenic AβPP processing in HEK-293 cells stably expressing human Swedish mutant APP695 and BACE1 (2EB2). Moreover, ODN could inhibit Aβ-induced oxidative stress in primary cultured cells and mice, as reflected by a dramatic increase in antioxidants and a decrease in pro-oxidants. We also found that ODN could reduce oxidative stress-induced apoptosis by restoring mitochondrial membrane potential, intracellular Ca2+ and cleaved caspase-3 levels in Aβ-treated primary cultured cells and mice. More importantly, intracerebroventricular injection of ODN attenuated cognitive impairments as well as long-term potentiation in Aβ-treated mice.

CONCLUSION

These results suggest that ODN may exert a potent neuroprotective effect against Aβ-induced neurotoxicity and memory decline via its antioxidant effects, indicating that ODN may be a potential therapeutic agent for AD.

Associations Between Mild Cognitive Impairment and Whole Blood Zinc and Selenium in the Elderly Cohort

Some studies have shown that an imbalance in trace element homeostasis can lead to cognitive dysfunction, but data are lacking. The purpose of this study was to investigate the association between whole blood zinc (Zn), selenium (Se), copper-zinc ratio (Cu/Zn), copper-selenium ratio (Cu/Se), and zinc-selenium ratio (Zn/Se) and mild cognitive impairment (MCI) in elderly Chinese individuals. The study was based on the Elderly Health and Controlled Environmental Factors Cohort in Lu'an, Anhui Province, China, from June to September 2016. The cognitive function of the elderly was determined by the Mini-Mental State Examination (MMSE) and activities of daily living (ADL) scales. The concentrations of Zn, Cu, and Se in the whole blood were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Binary logistic regression was used to analyze the associations between trace elements and MCI. A total of 1006 participants with an average age of 71.70 years old were included in this study. Compared with healthy people, MCI patients had higher whole blood Zn levels and lower Se levels, and Cu/Zn, Cu/Se, and Zn/Se were also significantly different. Binary logistic regression analysis showed that Zn, Cu/Se, and Zn/Se exposure in the third tertile was associated with an increased risk of MCI, while Se exposure in the third tertile was associated with a reduced risk of MCI. After adjustment for sex, age, marital status, BMI, and living status, whole blood Zn, Se, Cu/Zn, Cu/Se, and Zn/Se were significantly associated with MCI risk, especially in elderly women.

Design, Synthesis, Calculation and Biological Activity Studies Based on Privileged Coumarin Derivatives as Multifunctional Anti-AD Lead Compound

Coumarins and their derivatives possessed a variety of biological activities and some of coumarin-based drugs have been approved by the US Food and Drug Administration. Alzheimer's disease (AD) has caused great losses to human society. However, due to its complex pathogenesis, the ideal therapeutic approach has not been found yet. Free radical scavenging activity which is one of the main activities of coumarin core structure is closely related to other anti-AD activities. Therefore, in this work coumarins were chosen as privileged lead compounds for the development of anti-AD drugs based on strategy of multi-target directed ligands (MTDLs). Derivatives 1-3 which could modulate multiple targets simultaneously, including ROS, cholinesterase, βamyloid (Aβ) aggregation, and metal dyshomeostasis were designed and for the first time synthesized. Their anti-AD activities were studied both in vitro and in silico. Results showed that 1-3 possessed potent antioxidant activities and 7-OH group did change the electron distribution of the molecule and enhance the antioxidant activities. They also have good inhibition activities on acetylcholinesterase (AChE) and Aβ aggregation and compound 1 had the strongest AChE inhibitory effect among the three compounds (AChE IC₅₀ =11.15 μM). Compound 1-3 could also selectively chelate with Cu²⁺ and Al³⁺ to regulate the metal homeostasis. In silico simulations, including molecular docking and prediction of ADMET performance, indicated that 1-3 could interact with target proteins and cross the blood brain barrier. In conclusion, 1-3 could be promising MTDLs applied as anti-AD candidate drugs.

Cognitive enhancing effects and anticholinesterase activity of stem bark and leaf extracts of Prunus africana

Alzheimer's disease is ranked among the top five causes of death for old people. Globally, it is approximated that there are 7.7 million new cases of Alzheimer's disease per annum and it is expected that by the year 2050, as many as 1.5% of people will be victims of Alzheimers or other types of dementia. Currently there is no cure for Alzheimer's disease and the conventional therapeutics agents available either have low efficacy or are associated with serious side effects. In the current study, in vivo cognitive advancing and anticholinesterase effects of crude methanol extracts of stem bark and leaf of Prunus africana were investigated in scopolamine treated mice. Passive avoidance task was used to evaluate cognitive enhancing effects of the two plant extracts. Donepezil was used as the standard drug. Scopolamine butylbromide (5 mg/kg bw) was administered intraperitoneally to induce Alzheimer's disease in mice during the study. A completely controlled randomised experimental design was employed in the current study. The two extracts displayed significant anticholinesterase activities and improved cognition in a dose dependent fashion as indicated by escape latency trends. From the current study, it is concluded that methanol extracts of stem bark and leaf of P. africana contain phytochemicals with anticholinesterase activity and cognitive enhancing effects in scopolamine treated mice. The study therefore supports use of leaf and stem bark extracts of P. africana for management of dementia by traditional herbal practitioners.

Synchronous Extraction, Antioxidant Activity Evaluation, and Composition Analysis of Carbohydrates and Polyphenols Present in Artichoke Bud

This study investigated the optimization of ultrasonic-assisted aqueous two-phase synchronous extraction of carbohydrates and polyphenols present in artichoke bud, evaluated their antioxidant activities in vitro, and analyzed the composition of carbohydrates and polyphenols by high-performance liquid chromatography (HPLC). The powder mass, ultrasonic time, ammonium sulfate concentration, and alcohol-water ratio were considered the influencing factors based on the single-factor experiment results, and a dual-response surface model was designed to optimize the synchronous extraction process to extract carbohydrates and polyphenols. The antioxidant activity was evaluated by measuring the scavenging capacity of ABTS⁺· and DPPH· and the reducing capacity of Fe³⁺. The optimal process conditions in this study were as follows: the powder mass of 1.4 g, ammonium sulfate concentration of 0.34 g/mL, alcohol-water ratio of 0.4, and ultrasonic time of 43 min. The polyphenol content in artichoke bud was 5.32 ± 0.13 mg/g, and the polysaccharide content was 74.78 ± 0.11 mg/g. An experiment on in vitro antioxidant activity showed that both carbohydrates and polyphenols had strong antioxidant activities, and the antioxidant activity of polyphenols was stronger than that of carbohydrates. The HPLC analysis revealed that the carbohydrates in artichoke bud were mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, and arabinose, and the molar ratio was 10.77:25.22:2.37:15.74:125.39:48.62:34.70. The polyphenols comprised chlorogenic acid, 4-dicaffeoylquinic acid, caffeic acid, 1,3-dicaffeoylqunic acid, isochlorogenic acid B, isochlorogenic acid A, cynarin, and isochlorogenic acid C, and the contents were 0.503, 0.029, 0.022, 0.017, 0.008, 0.162, 1.621, 0.030 mg/g, respectively. This study also showed that the carbohydrates and polyphenols in artichoke bud could be important natural antioxidants, and the composition analysis of HPLC provided directions for their future research. Carbohydrates and polyphenols in artichoke buds can be separated and enriched using the optimized process technology, and it is an effective means of extracting ingredients from plants.

Comprehensive physiological, transcriptomic, and metabolomic analyses reveal the synergistic mechanism of Bacillus pumilus G5 combined with silicon alleviate oxidative stress in drought-stressed Glycyrrhiza uralensis Fisch

Glycyrrhiza uralensis Fisch. is often cultivated in arid, semi-arid, and salt-affected regions that suffer from drought stress, which leads to the accumulation of reactive oxygen species (ROS), thus causing oxidative stress. Plant growth-promoting bacteria (PGPB) and silicon (Si) have been widely reported to be beneficial in improving the tolerance of plants to drought stress by maintaining plant ROS homeostasis. Herein, combining physiological, transcriptomic, and metabolomic analyses, we investigated the response of the antioxidant system of G. uralensis seedlings under drought stress to Bacillus pumilus (G5) and/or Si treatment. The results showed that drought stress caused the overproduction of ROS, accompanied by the low efficiency of antioxidants [i.e., superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), the ascorbate (AsA)-glutathione (GSH) pool, total carotenoids, and total flavonoids]. Inversely, supplementation with G5 and/or Si enhanced the antioxidant defense system in drought-stressed G. uralensis seedlings, and the complex regulation of the combination of G5 and Si differed from that of G5 or Si alone. The combination of G5 and Si enhanced the antioxidant enzyme system, accelerated the AsA-GSH cycle, and triggered the carotenoid and flavonoid metabolism, which acted in combination via different pathways to eliminate the excess ROS induced by drought stress, thereby alleviating oxidative stress. These findings provide new insights into the comparative and synergistic roles of PGPB and Si in the antioxidant system of plants exposed to drought and a guide for the application of PGPB combined with Si to modulate the tolerance of plants to stress.

Therapeutic approaches of nutraceuticals in the prevention of Alzheimer's disease

Alzheimer's disease (AD) is a neurological illness that causes memory loss over time. Currently, available pharmaceutical medicines and products are limited, and they have side effects at a higher price. Researchers and scientists have observed significant effects of nutraceuticals. Various preclinical and clinical studies were investigated for the Anti-Alzheimer's activity of nutraceuticals. The increasing ability of the pathogenesis of AD has led to the analysis of novel therapeutic targets, including the pathophysiological mechanisms and distinct cascades. So, current improvement will show the most adequate and prominent nutraceuticals and suggested concise mechanisms involving autophagy regulation, anti-inflammatory, antioxidant, mitochondrial homeostasis, and others. The effects of nutraceuticals cannot be ignored; it is important to investigate high-quality clinical trials. Given the potential of nutraceuticals to battle AD as multi-targeted therapies, it's vital to evaluate them as viable lead compounds for drug discovery and development. To the best of the authors 'knowledge, modification of blood-brain barrier permeability, bioavailability, and aspects of randomized clinical trials should be considered in prospective investigations. PRACTICAL APPLICATIONS: Advancements in molecular diagnostic and fundamentals have implemented particular usefulness for drug evaluation. An excess of experimental knowledge occurs regarding the effect of nutraceuticals on AD. There are various preclinical and clinical studies that have been done on nutraceuticals. In addition, various substitute inhibit and enhance some pathophysiological levels associated with AD. Nutraceuticals are easily available and have fewer side effects with cost-effective advantages. However, further investigations and clinical trials are required to encourage its effect on disease.

The AMPK-SIRT1-FoxO1-NF-κB signaling pathway participates in hesperetin-mediated neuroprotective effects against traumatic brain injury via the NLRP3 inflammasome

BACKGROUND

Traumatic brain injury (TBI) induces inflammations that lead to secondary damage. Hesperetin (Hes) exerts anti-inflammatory activities against central nervous system (CNS) diseases. This article probes the possible neuroprotective effect and mechanism of Hes on TBI-induced acute cerebral damage.

METHODS

Male C57BL/6J mice were subjected to controlled cortical impingement (CCI) and Hes (50 mg/kg) treatment after the surgery. Short-term neurological deficits were assessed with the modified neurological severity score (mNSS) and the Rota-rod test. The brain edema was tested by the wet/dry method. Neuron apoptosis was evaluated by Nissl staining and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. The blood-brain barrier (BBB) integrity was measured by Evans' blue staining, and immunohistochemistry (IHC) was conducted to study BV2 microglial activation. BV2 microglia and HT22 neuronal cells were stimulated by oxygen-glucose deprivation followed by recovery (OGD/R) and processed with Hes. Quantitative real-time-polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were implemented to gauge the expression of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-β (IL-1-β) and interleukin-6 (IL-6). Western blot (WB) was performed to check AMPK-SIRT1-FoxO1 both in vitro and in vivo.

RESULTS

Hes eased neurological deficits, cerebral edema, and neuronal apoptosis in mice following TBI. Hes hampered microglial activation and pro-inflammatory cytokines production. Hes promoted AMPK and SIRT1 expression, whereas repressed the phosphorylation of FoxO1-NF-κB, and inhibited NLRP3 expression. The AMPK inhibitor Compound C markedly reversed Hes-mediated anti-inflammatory and neuron-protective effects.

CONCLUSION

Hes curbs microglial activation-mediated inflammation via the AMPK-SIRT1-FoxO1-NF-κB axis, thereby improving neurobehavioral function after TBI.

Novel Dual AChE and ROCK2 Inhibitor Induces Neurogenesis via PTEN/AKT Pathway in Alzheimer's Disease Model

Alzheimer's disease (AD) is a progressive and complex neurodegenerative disease. Acetylcholinesterase inhibitors (AChEIs) are a major class of drugs used in AD therapy. ROCK2, another promising target for AD, has been associated with the induction of neurogenesis via PTEN/AKT. This study aimed to characterize the therapeutic potential of a novel donepezil-tacrine hybrid compound (TA8Amino) to inhibit AChE and ROCK2 protein, leading to the induction of neurogenesis in SH-SY5Y cells. Experiments were carried out with undifferentiated and neuron-differentiated SH-SY5Y cells submitted to treatments with AChEIs (TA8Amino, donepezil, and tacrine) for 24 h or 7 days. TA8Amino was capable of inhibiting AChE at non-cytotoxic concentrations after 24 h. Following neuronal differentiation for 7 days, TA8Amino and donepezil increased the percentage of neurodifferentiated cells and the length of neurites, as confirmed by β-III-tubulin and MAP2 protein expression. TA8Amino was found to participate in the activation of PTEN/AKT signaling. In silico analysis showed that TA8Amino can stably bind to the active site of ROCK2, and in vitro experiments in SH-SY5Y cells demonstrate that TA8Amino significantly reduced the expression of ROCK2 protein, contrasting with donepezil and tacrine. Therefore, these results provide important information on the mechanism underlying the action of TA8Amino with regard to multi-target activities.

Amyloid Beta in Aging and Alzheimer's Disease

Alzheimer's disease (AD), is a progressive neurodegenerative disease that affects behavior, thinking, learning, and memory in elderly individuals. AD occurs in two forms, early onset familial and late-onset sporadic; genetic mutations in PS1, PS2, and APP genes cause early onset familial AD, and a combination of lifestyle, environment and genetic factors causes the late-onset sporadic form of the disease. However, accelerated disease progression is noticed in patients with familial AD. Disease-causing pathological changes are synaptic damage, and mitochondrial structural and functional changes, in addition to increased production and accumulation of phosphorylated tau (p-tau), and amyloid beta (Aβ) in the affected brain regions in AD patients. Aβ is a peptide derived from amyloid precursor protein (APP) by proteolytic cleavage of beta and gamma secretases. APP is a glycoprotein that plays a significant role in maintaining neuronal homeostasis like signaling, neuronal development, and intracellular transport. Aβ is reported to have both protective and toxic effects in neurons. The purpose of our article is to summarize recent developments of Aβ and its association with synapses, mitochondria, microglia, astrocytes, and its interaction with p-tau. Our article also covers the therapeutic strategies that reduce Aβ toxicities in disease progression and discusses the reasons for the failures of Aβ therapeutics.

Essential metals in health and disease

In total, twenty elements appear to be essential for the correct functioning of the human body, half of which are metals and half are non-metals. Among those metals that are currently considered to be essential for normal biological functioning are four main group elements, sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca), and six d-block transition metal elements, manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn) and molybdenum (Mo). Cells have developed various metallo-regulatory mechanisms for maintaining a necessary homeostasis of metal-ions for diverse cellular processes, most importantly in the central nervous system. Since redox active transition metals (for example Fe and Cu) may participate in electron transfer reactions, their homeostasis must be carefully controlled. The catalytic behaviour of redox metals which have escaped control, e.g. via the Fenton reaction, results in the formation of reactive hydroxyl radicals, which may cause damage to DNA, proteins and membranes. Transition metals are integral parts of the active centers of numerous enzymes (e.g. Cu,Zn-SOD, Mn-SOD, Catalase) which catalyze chemical reactions at physiologically compatible rates. Either a deficiency, or an excess of essential metals may result in various disease states arising in an organism. Some typical ailments that are characterized by a disturbed homeostasis of redox active metals include neurological disorders (Alzheimer's, Parkinson's and Huntington's disorders), mental health problems, cardiovascular diseases, cancer, and diabetes. To comprehend more deeply the mechanisms by which essential metals, acting either alone or in combination, and/or through their interaction with non-essential metals (e.g. chromium) function in biological systems will require the application of a broader, more interdisciplinary approach than has mainly been used so far. It is clear that a stronger cooperation between bioinorganic chemists and biophysicists - who have already achieved great success in understanding the structure and role of metalloenzymes in living systems - with biologists, will access new avenues of research in the systems biology of metal ions. With this in mind, the present paper reviews selected chemical and biological aspects of metal ions and their possible interactions in living systems under normal and pathological conditions.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia–reperfusion (I–R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I–R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

Role of Reactive Oxygen Species in Aging and Age-Related Diseases: A Review

Research on the role of reactive oxygen species (ROS) in the aging process has advanced significantly over the last two decades. In light of recent findings, ROS takes part in the aging process of cells along with contributing to various physiological signaling pathways. Antioxidants being cells' natural defense mechanism against ROS-mediated alteration, play an imperative role to maintain intracellular ROS homeostasis. Although the complete understanding of the ROS regulated aging process is yet to be fully comprehended, current insights into various sources of cellular ROS and their correlation with the aging process and age-related diseases are portrayed in this review. In addition, results on the effect of antioxidants on ROS homeostasis and the aging process as well as their advances in clinical trials are also discussed in detail. The future perspective in ROS-antioxidant dynamics on antiaging research is also marshaled to provide future directions for ROS-mediated antiaging research fields.

Development and validation of immune-based biomarkers and deep learning models for Alzheimer’s disease

Background: Alzheimer’s disease (AD) is the most common form of dementia in old age and poses a severe threat to the health and life of the elderly. However, traditional diagnostic methods and the ATN diagnostic framework have limitations in clinical practice. Developing novel biomarkers and diagnostic models is necessary to complement existing diagnostic procedures.

Methods: The AD expression profile dataset GSE63060 was downloaded from the NCBI GEO public database for preprocessing. AD-related differentially expressed genes were screened using a weighted co-expression network and differential expression analysis, and functional enrichment analysis was performed. Subsequently, we screened hub genes by random forest, analyzed the correlation between hub genes and immune cells using ssGSEA, and finally built an AD diagnostic model using an artificial neural network and validated it.

Results: Based on the random forest algorithm, we screened a total of seven hub genes from AD-related DEGs, based on which we confirmed that hub genes play an essential role in the immune microenvironment and successfully established a novel diagnostic model for AD using artificial neural networks, and validated its effectiveness in the publicly available datasets GSE63060 and GSE97760.

Conclusion: Our study establishes a reliable model for screening and diagnosing AD that provides a theoretical basis for adding diagnostic biomarkers for the AD gene.

Serotonin 5-HT6 Receptor Ligands and Butyrylcholinesterase Inhibitors Displaying Antioxidant Activity-Design, Synthesis and Biological Evaluation of Multifunctional Agents against Alzheimer's Disease

Neurodegeneration leading to Alzheimer’s disease results from a complex interplay of a variety of processes including misfolding and aggregation of amyloid beta and tau proteins, neuroinflammation or oxidative stress. Therefore, to address more than one of these, drug discovery programmes focus on the development of multifunctional ligands, preferably with disease-modifying and symptoms-reducing potential. Following this idea, herein we present the design and synthesis of multifunctional ligands and biological evaluation of their 5-HT₆ receptor affinity (radioligand binding assay), cholinesterase inhibitory activity (spectroscopic Ellman’s assay), antioxidant activity (ABTS assay) and metal-chelating properties, as well as a preliminary ADMET properties evaluation. Based on the results we selected compound 14 as a well-balanced and potent 5-HT₆ receptor ligand (K_i = 22 nM) and human BuChE inhibitor (IC₅₀ = 16 nM) with antioxidant potential expressed as a reduction of ABTS radicals by 35% (150 μM). The study also revealed additional metal-chelating properties of compounds 15 and 18. The presented compounds modulating Alzheimer’s disease-related processes might be further developed as multifunctional ligands against the disease.

Benefits and limitations of nanomedicine treatment of brain cancers and age-dependent neurodegenerative disorders

The treatment of central nervous system (CNS) malignancies, including brain cancers, is limited by a number of obstructions, including the blood-brain barrier (BBB), the heterogeneity and high invasiveness of tumors, the inaccessibility of tissues for early diagnosis and effective surgery, and anti-cancer drug resistance. Therapies employing nanomedicine have been shown to facilitate drug penetration across the BBB and maintain biodistribution and accumulation of therapeutic agents at the desired target site. The application of lipid-, polymer-, or metal-based nanocarriers represents an advanced drug delivery system for a growing group of anti-cancer chemicals. The nanocarrier surface is designed to contain an active ligand (cancer cell marker or antibody)-binding structure which can be modified to target specific cancer cells. Glioblastoma, ependymoma, neuroblastoma, medulloblastoma, and primary CNS lymphomas were recently targeted by easily absorbed nanocarriers. The metal- (such as transferrin drug-loaded systems), polymer- (nanocapsules and nanospheres), or lipid- (such as sulfatide-containing nanoliposomes)-based nano-vehicles were loaded with apoptosis- and/or ferroptosis-stimulating agents and demonstrated promising anti-cancer effects. This review aims to discuss effective nanomedicine approaches designed to overcome the current limitations in the therapy of brain cancers and age-dependent neurodegenerative disorders. To accent current obstacles for successful CNS-based cancer therapy, we discuss nanomedicine perspectives and limitations of nanodrug use associated with the specificity of nervous tissue characteristics and the effects nanocarriers have on cognition.

Targeting Microglia in Alzheimer’s Disease: From Molecular Mechanisms to Potential Therapeutic Targets for Small Molecules

Alzheimer’s disease (AD) is a common, progressive, and devastating neurodegenerative disorder that mainly affects the elderly. Microglial dysregulation, amyloid-beta (Aβ) plaques, and intracellular neurofibrillary tangles play crucial roles in the pathogenesis of AD. In the brain, microglia play roles as immune cells to provide protection against virus injuries and diseases. They have significant contributions in the development of the brain, cognition, homeostasis of the brain, and plasticity. Multiple studies have confirmed that uncontrolled microglial function can result in impaired microglial mitophagy, induced Aβ accumulation and tau pathology, and a chronic neuroinflammatory environment. In the brain, most of the genes that are associated with AD risk are highly expressed by microglia. Although it was initially regarded that microglia reaction is incidental and induced by dystrophic neurites and Aβ plaques. Nonetheless, it has been reported by genome-wide association studies that most of the risk loci for AD are located in genes that are occasionally uniquely and highly expressed in microglia. This finding further suggests that microglia play significant roles in early AD stages and they be targeted for the development of novel therapeutics. In this review, we have summarized the molecular pathogenesis of AD, microglial activities in the adult brain, the role of microglia in the aging brain, and the role of microglia in AD. We have also particularly focused on the significance of targeting microglia for the treatment of AD.

On the reactions of Cu(II/I)ATP complexes with methyl radicals

The Cu^I/IIATP react with methyl radicals to form methane and methanol, where Cu^IATP reacts with ^•CH₃ in a process that is surprisingly slow. The low-rate constant of this process is attributed to the significant rearrangement of the chelating ligand required for the transient's formation. These results were corroborated by DFT calculations of the relevant compounds.

Protective effects of Persea americana fruit and seed extracts against chemically induced liver cancer in rats by enhancing their antioxidant, anti-inflammatory, and apoptotic activities

This study aims to explore the chemopreventive mechanisms of hydroethanolic extracts from avocado (Persea Americana) in diethylnitrosamine (DEN)/2-acetylaminofluorene (2AAF)-induced hepatocarcinogenesis. Chemical induction of hepatocarcinogenesis was induced by intraperitoneal injection of DEN at 150 mg/kg body weight (b.w.) twice a week for a fortnight, followed by oral administration of 2AAF at 20 mg/kg b.w. four times a week for 3 weeks. Rats administered DEN/2AAF were orally treated with hydroethanolic extracts of avocado fruits and seeds at a dose of 50 mg/kg b.w. every other day for 20 weeks. Moreover, rats administered DEN/2AAF and treated with avocado extracts revealed a marked decrease in liver enzyme activities, total bilirubin levels, and elevated liver tumor markers, but revealed an increase in total protein and albumin levels. The hepatocytes with hyperchromatic and bile duct cystadenoma observed in the liver of rats administered DEN/2AAF were reduced due to treatment with avocado extracts. Furthermore, the treatments prevented the elevation of lipid peroxidation levels and ameliorated the lowered glutathione peroxidase, glutathione-S-transferase, superoxide dismutase activities, and glutathione content in the liver tissues. Also, antigen Ki-67, cyclooxygenase-2, and nuclear factor kappa-B expression levels were decreased, but of the suppressor proteins p53 and BAX levels were increased in the liver of rats administered DEN/2AAF and treated with avocado extracts. In conclusion, the current results demonstrated that avocado extracts could abate hepatocarcinogenesis in rats administered DEN/2AAF through activation of antioxidant, anti-inflammatory, and apoptotic properties.

Hesperetin, a Citrus Flavonoid, Ameliorates Inflammatory Cytokine-Mediated Inhibition of Oligodendroglial Cell Morphological Differentiation

Oligodendrocytes (oligodendroglial cells) are glial cells that wrap neuronal axons with their differentiated plasma membranes called myelin membranes. In the pathogenesis of inflammatory cytokine-related oligodendroglial cell and myelin diseases such as multiple sclerosis (MS), typical inflammatory cytokines tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) are thought to contribute to the degeneration and/or progression of the degeneration of oligodendroglial cells and, in turn, the degeneration of naked neuronal cells in the central nervous system (CNS) tissues. Despite the known involvement of these inflammatory cytokines in disease progression, it has remained unclear whether and how TNFα or IL-6 affects the oligodendroglial cells themselves or indirectly. Here we show that TNFα or IL-6 directly inhibits morphological differentiation in FBD-102b cells, which are differentiation models of oligodendroglial cells. Their phenotype changes were supported by the decreased expression levels of oligodendroglial cell differentiation and myelin marker proteins. In addition, TNFα or IL-6 decreased phosphorylation levels of Akt kinase, whose upregulation has been associated with promoting oligodendroglial cell differentiation. Hesperetin, a flavonoid mainly contained in citrus fruit, is known to have neuroprotective effects. Hesperetin might also be able to resolve pre-illness conditions, including the irregulated secretion of cytokines, through diet. Notably, the addition of hesperetin into cells recovered TNFα- or IL-6-induced inhibition of differentiation, as supported by increased levels of marker protein expression and phosphorylation of Akt kinase. These results suggest that TNFα or IL-6 itself contributes to the inhibitory effects on the morphological differentiation of oligodendroglial cells, possibly providing information not only on their underlying pathological effects but also on flavonoids with potential therapeutic effects at the molecular and cellular levels.

Butyrylcholinesterase inhibitors as potential anti-Alzheimer's agents: an updated patent review (2018-present)

INTRODUCTION

Alzheimer's disease (AD) constitutes one of the most complex and devastating diseases, with an extraordinarily high increase expected for the next few years. Despite the numerous efforts accomplished so far there is still no cure but just palliative treatments.

AREAS COVERED

The main topic covered herein has been the development of butyrylcholinesterase (BuChE) inhibitors with the aim of increasing the levels of the neurotransmitter acetylcholine (ACh). Two main groups of compounds have been considered: multitarget and non-multitarget ligands, depending if the structural design is focused or not on other key targets and pathogenic factors of the disease. Seventeen patents regarding multitarget-directed ligands (MTDLs), twelve for not multitarget derivatives, and three for miscellaneous uses have been covered in the period 2018‒2021.

EXPERT OPINION

BuChE is an attractive target in the treatment of AD for many reasons. It is the most prevalent cholinesterase within more advanced stages of the disease, so drugs inhibiting it would be suitable for the treatment of mid- to severe Alzheimer's patients. Moreover, BuChE has been proved to be connected with some other key hallmarks of the disease, like amyloidogenesis; hybridization of a BuChE-targeting pharmacophore with other scaffolds designed for other therapeutic targets is quite a promising design for potential anti-Alzheimer's drugs.

An Overview of Oxidative Stress, Neuroinflammation, and Neurodegenerative Diseases

Oxidative stress has been linked with a variety of diseases, being involved in the debut and/or progress of several neurodegenerative disorders. This review intends to summarize some of the findings that correlate the overproduction of reactive oxygen species with the pathophysiology of Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. Oxidative stress was also noted to modify the inflammatory response. Even though oxidative stress and neuroinflammation are two totally different pathological events, they are linked and affect one another. Nonetheless, there are still several mechanisms that need to be understood regarding the onset and the progress of neurodegenerative diseases in order to develop efficient therapies. As antioxidants are a means to alter oxidative stress and slow down the symptoms of these neurodegenerative diseases, the most common antioxidants, enzymatic as well as non-enzymatic, have been mentioned in this paper as therapeutic options for the discussed disorders.

Chemical Composition, Antioxidant and Anti-Enzymatic Activity of Golden Root (Rhodiola rosea L.) Commercial Samples

The aim of the study was to compare the chemical composition of the water and hydromethanolic extracts of R. rosea commercial samples in relation to their biological activity. For this purpose, the HPLC method was used for the determination of eleven phenolic compounds and AAS/AES was used for determination of five essential elements. Moreover, the contents of total phenolic, total flavonoid, total phenolic acids, and L(+)-ascorbic acid were determined. The antioxidant activity was assessed by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS radical scavenging activity, ferric-reducing/antioxidant power (FRAP), and cupric-reducing antioxidant capacity (CUPRAC) assays, while the inhibitory activity against AChE and BChE enzymes was determined using Ellman’s method. The results showed that the hydromethanolic extracts of R. rosea were richer in phenolic compounds and showed higher antioxidant and neurobiological activity than the water extracts. However, the water extracts gave higher contents of determined elements. Among the individual phenolic compounds gallic acid (2.33 mg/g DW) and sinapic acid (386.44 µg/g DW) had the highest concentrations in the hydromethanolic and water extracts, respectively. Moreover, the most extracts were observed to be more efficient on BChE. Moreover, the correlation analysis indicated a high positive relationship between chemical composition and biological activity in both extracts of R. rosea.

Multiple Roles of Paeoniflorin in Alzheimer's Disease

Alzheimer's disease (AD) is a geriatric disease with the morbidity and mortality continuing to grow, partly due to the aging of the world population. As one of the most common types of primary neurodegenerative dementia, it is mainly due to environmental, epigenetic, immunological, and genetic factors. Paeoniflorin (PF), the main component of paeony extract, plays a more and more important role in the prevention and treatment of AD, including regulating protein, anti-inflammation, antioxidation, and antiapoptosis, protecting glial cells, regulating neurotransmitters and related enzymes and receptors, and inhibiting or activating related signal pathways. This article summarizes the latest researches on the multiple effects and the mechanisms of PF in the treatment to cure AD, providing new insights and research basis for further clinical application of traditional Chinese medicine (TCM) in the treatment of AD.

Rutin Inhibits Cardiac Apoptosis and Prevents Sepsis-Induced Cardiomyopathy

Rutin is a flavanol-type polyphenol that consists of flavanol quercetin and the disaccharide rutinose, which has been reported to exert various biological effects such as antioxidant and anti-inflammatory activities. It is not clear whether rutin has a protective effect on sepsis-induced cardiomyopathy (SIC). In this study, we used male C57BL/6 mice and cecal ligation and puncture (CLP) surgery to establish the model of SIC. Rutin was precautionarily treated (50, 100, 200 mg/kg per day, 7 days) before CLP. The results showed that rutin pretreatment (100, 200 mg/kg per day, 7 days) reduced the mortality of murine sepsis. We chose the 100 mg/kg dose for further studies. Mice were pretreatment with rutin (100 mg/kg per day, 7 days) before subjected to CLP, and myocardial tissue and blood samples were collected 24 h after CLP. Serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and cTNT decreased, while interleukin-10 (IL-10) increased with rutin pretreatment. The cardiomyocytes apoptosis and mitochondrial dysfunction were also alleviated with rutin pretreatment. In conclusion, this study confirmed the efficacy of rutin-enriched diet in the prophylaxis of cardiac apoptosis and cardiac injury induced by CLP in mouse model. It provides a potential new approach on SIC prophylaxis in sepsis.

Uncommon Noninvasive Biomarkers for the Evaluation and Monitoring of the Etiopathogenesis of Alzheimer's Disease

Background:

Alzheimer´s disease (AD) is the most widespread dementia in the world, followed by vascular dementia. Since AD is a heterogeneous disease that shows several varied phenotypes, it is not easy to make an accurate diagnosis, so it arises when the symptoms are clear and the disease is already very advanced. Therefore, it is important to find out biomarkers for AD early diagnosis that facilitate treatment or slow down the disease. Classic biomarkers are obtained from cerebrospinal fluid and plasma, along with brain imaging by positron emission tomography. Attempts have been made to discover uncommon biomarkers from other body fluids, which are addressed in this update.

Objective:

This update aims to describe recent biomarkers from minimally invasive body fluids for the patients, such as saliva, urine, eye fluid or tears.

Methods:

Biomarkers were determined in patients versus controls by single tandem mass spectrometry, and immunoassays. Metabolites were identified by nuclear magnetic resonance, and microRNAs with genome-wide high-throughput real-time polymerase chain reaction-based platforms.

Results:

Biomarkers from urine, saliva, and eye fluid were described, including peptides/proteins, metabolites, and some microRNAs. The association with AD neuroinflammation and neurodegeneration was analyzed, highlighting the contribution of matrix metalloproteinases, the immune system and microglia, as well as the vascular system.

Conclusion:

Unusual biomarkers have been developed, which distinguish each stage and progression of the disease, and are suitable for the early AD diagnosis. An outstanding relationship of biomarkers with neuroinflammation and neurodegeneration was assessed, clearing up concerns of the etiopathogenesis of AD.

Tau Toxicity in Neurodegeneration

Tau is a microtubule-associated protein widely distributed in the central nervous system (CNS). The main function of tau is to promote the assembly of microtubules and stabilize their structure. After a long period of research on neurodegenerative diseases, the function and dysfunction of the microtubule-associated protein tau in neurodegenerative diseases and tau neurotoxicity have attracted increasing attention. Tauopathies are a series of progressive neurodegenerative diseases caused by pathological changes in tau, such as abnormal phosphorylation. The pathological features of tauopathies are the deposition of abnormally phosphorylated tau proteins and the aggregation of tau proteins in neurons. This article first describes the normal physiological function and dysfunction of tau proteins and then discusses the enzymes and proteins involved in tau phosphorylation and dephosphorylation, the role of tau in cell dysfunction, and the relationships between tau and several neurodegenerative diseases. The study of tau neurotoxicity provides new directions for the treatment of tauopathies.

Phytochemical Characterization, and Antioxidant and Antimicrobial Properties of Agitated Cultures of Three Rue Species: Ruta chalepensis, Ruta corsica, and Ruta graveolens

The in vitro cultures of the following three species of the genus Ruta were investigated: R. chalepensis, R. corsica, and R. graveolens. The dynamics of biomass growth and accumulation of secondary metabolites in the 3-, 4-, 5-, 6-, and 7-week growth cycle were analysed. The antioxidant capacity of the methanol extracts obtained from the biomass of the in vitro cultures was also assessed by different in vitro assays: 1,1-diphenyl-2-picrylhydrazil (DPPH), reducing power, and Fe²⁺ chelating activity assays. Moreover, a preliminary screening of the antimicrobial potential of the extracts was performed. The extracts were phytochemically characterized by high-performance liquid chromatography (HPLC), which highlighted the presence of linear furanocoumarins (bergapten, isoimperatorin, isopimpinellin, psoralen, and xanthotoxin) and furoquinoline alkaloids (γ-fagarine, 7-isopentenyloxy-γ-fagarine, and skimmianine). The dominant group of compounds in all the cultures was coumarins (maximum content 1031.5 mg/100 g DW (dry weight), R. chalepensis, 5-week growth cycle). The results of the antioxidant tests showed that the extracts of the three species had varied antioxidant capacity: in particular, the R. chalepensis extract exhibited the best radical scavenging activity (IC₅₀ = 1.665 ± 0.009 mg/mL), while the R. graveolens extract displayed the highest chelating property (IC₅₀ = 0.671 ± 0.013 mg/mL). Finally, all the extracts showed good activity against Staphylococcus aureus with MIC values of 250 μg/mL for the R. corsica extract and 500 μg/mL for both R. graveolens and R. chalepensis extracts.

(±)-Catechin—A Mass-Spectrometry-Based Exploration Coordination Complex Formation with FeII and FeIII

Catechin is an extensively investigated plant flavan-3-ol with a beneficial impact on human health that is often associated with antioxidant activities and iron coordination complex formation. The aim of this study was to explore these properties with FeII and FeIII using a combination of nanoelectrospray-mass spectrometry, differential pulse voltammetry, site-specific deoxyribose degradation assay, FeII autoxidation assay, and brine shrimp mortality assay. Catechin primarily favored coordination complex formation with Fe ions of the stoichiometry catechin:Fe in the ratio of 1:1 or 2:1. In the detected Fe–catechin coordination complexes, FeII prevailed. Differential pulse voltammetry, the site-specific deoxyribose degradation, and FeII autoxidation assays proved that coordination complex formation affected catechin’s antioxidant effects. In situ formed Fe–catechin coordination complexes showed no toxic activities in the brine shrimp mortality assay. In summary, catechin has properties for the possible treatment of pathological processes associated with ageing and degeneration, such as Alzheimer’s and Parkinson’s diseases.

Inhibitory activities of grape bioactive compounds against enzymes linked with human diseases

A quest for identification of novel, safe and efficient natural compounds, as additives in the modern food and cosmetic industries, has been prompted by concerns about toxicity and side effects of synthetic products. Plant phenolic compounds are one of the most documented natural products due to their multifarious biological applications. Grape (Vitis vinifera) is an important source of phenolic compounds such as phenolic acids, tannins, quinones, coumarins and, most importantly, flavonoids/flavones. This review crisply encapsulates enzyme inhibitory activities of various grape polyphenols towards different key human-ailment-associated enzymes: xanthine oxidase (gout), tyrosinase (hyperpigmentation), α-amylase and α-glucosidase (diabetes mellitus), pancreatic lipase (obesity), cholinesterase (Alzheimer's disease), angiotensin i-converting enzymes (hypertension), α-synuclein (Parkinson's disease) and histone deacetylase (various diseases). The review also depicts the enzyme inhibitory mechanism of various grape polyphenols and briefly discusses their stature as potential therapeutic and drug development candidates. KEY POINTS: • Nineteen major bioactive polyphenols from the grape/grape products and their disease targets are presented • Sixty-two important polyphenols as enzyme inhibitors from grape/grape products are presented • A thorough description and graphical presentation of biological significance of polyphenols against various diseases.

Beneficial Effects of a Combination of Curcuma longa L. and Citrus junos Against Beta-Amyloid Peptide-Induced Neurodegeneration in Mice

Both Curcuma longa (CL) and Citrus junos Tanaka (CJ) have been used to treat various diseases due to their anti-inflammatory and antioxidative stress activities. In this study, we investigated the ameliorative effect of the combination of CL extract and CJ extract (CCC) against beta-amyloid (Aβ) peptide-induced neurological damage. CCC prevented neurocytotoxicity in vitro. In addition, it was confirmed that abnormal alternation behavior and memory impairment caused by Aβ peptide were reversed by treatment with CCC. Furthermore, CCC treatment led to recovery of the cholinergic system and reactive oxygen species (ROS) oxidative damage defense system. CCC induced expressions of cyclic-adenosine monophosphate response element-binding protein (CREB)-responsive element-binding protein and brain-derived neurotrophic factor were confirmed as was the significantly improved processing in the hippocampus of the mouse Aβ peptides. Accordingly, these results suggest that CCC can prevent and/or reverse neurocytotoxicity and cognitive deficits in a mouse model of Alzheimer's disease.

Protection against Amyloid-β Oligomer Neurotoxicity by Small Molecules with Antioxidative Properties: Potential for the Prevention of Alzheimer’s Disease Dementia

Soluble oligomeric assemblies of amyloid β-protein (Aβ), called Aβ oligomers (AβOs), have been recognized as primary pathogenetic factors in the molecular pathology of Alzheimer’s disease (AD). AβOs exert neurotoxicity and synaptotoxicity and play a critical role in the pathological progression of AD by aggravating oxidative and synaptic disturbances and tau abnormalities. As such, they are important therapeutic targets. From a therapeutic standpoint, it is not only important to clear AβOs or prevent their formation, it is also beneficial to reduce their neurotoxicity. In this regard, recent studies have reported that small molecules, most with antioxidative properties, show promise as therapeutic agents for reducing the neurotoxicity of AβOs. In this mini-review, we briefly review the significance of AβOs and oxidative stress in AD and summarize studies on small molecules with AβO-neurotoxicity-reducing effects. We also discuss mechanisms underlying the effects of these compounds against AβO neurotoxicity as well as their potential as drug candidates for the prevention and treatment of AD.

New uses of Melatonin as a Drug, a Review

Melatonin is a simple compound with a proper chemical name N-acetyl-5-methoxy tryptamine and known as a hormone controlling circadian rhythm. Humans produce melatonin at night which is the reason for sleeping in the night and awakening over the day. Melatonin interacts with melatonin receptors MT1 and MT2 but it was also revealed that melatonin is a strong antioxidant and it also has a role in regulation of cell cycle. Currently, melatonin is used as a drug for some types of sleep disorder but the recent research points to the fact that melatonin can also serve for the other purposes including prophylaxis or therapy of lifestyle diseases, cancer, neurodegenerative disorders and exposure to chemicals. This review summarizes basic facts and direction of the current research on melatonin. The actual literature was scrutinized for the purpose of this review.