Ameliorative effects of astaxanthin on brain tissues of alzheimer's disease-like model: cross talk between neuronal-specific microRNA-124 and related pathways

Neuroprotective effects of astaxanthin in a scopolamine-induced rat model of Alzheimer's disease through antioxidant/anti-inflammatory pathways and opioid/benzodiazepine receptors: attenuation of Nrf2, NF-κB, and interconnected pathways

Background

Given the complexity of pathological mechanisms behind Alzheimer's disease (AD), there is a pressing need for novel multi-targeting therapeutic agents. Astaxanthin, a natural compound with diverse biological effects, has emerged as a potential candidate in neuronal diseases.

Purpose

This study aimed to evaluate the neuroprotective effects of astaxanthin in a scopolamine-induced rat model of AD.

Materials and methods

In total, 36 male Wistar rats were divided into six groups, including a control group receiving normal saline, a negative control group treated with scopolamine (1 mg/kg), and two groups receiving astaxanthin at doses of 5 and 10 mg/kg. Additionally, two groups were pre-treated with naloxone (0.1 mg/kg) or flumazenil (0.5 mg/kg) to block opioid and benzodiazepine receptors, respectively, followed by receiving the most effective dose of astaxanthin (i.e., 10 mg/kg). Treatments were administered via intraperitoneal injection for 14 consecutive days and behavioral tests were done. Biochemical analyses, zymography, Western blotting, and histopathological examinations were also performed.

Results and discussion

Astaxanthin treatment significantly improved cognitive function, enhanced plasma antioxidant capacity by increasing catalase and glutathione levels, and reduced nitrite levels. It also increased serum activity of matrix metalloproteinase 2 (MMP-2), while decreasing MMP-9, increasing the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2) and decreasing nuclear factor kappa B (NF-κB) in hippocampal tissue. Histopathological findings indicated reduced hippocampal damage after astaxanthin administration. The aforementioned protective effects of astaxanthin were reversed by naloxone and flumazenil.

Conclusion

Astaxanthin demonstrates protective effects against scopolamine-induced AD through its neuroprotective, antioxidant, and anti-inflammatory properties, potentially involving interactions with opioid and benzodiazepine receptors.

Exploring astaxanthin: a comprehensive review on its pharmacokinetics properties and neuroprotective potential

BACKGROUND

Carotenoids are naturally occurring bio-pigments found in microalgae, plants, fungi, bacteria, and various aquatic animals. They are generally classified into carotenes and xanthophylls based on their structural features. Among them, astaxanthin-a xanthophyll carotenoid-has attracted increasing attention due to its potent antioxidant, anti-inflammatory, and anti-apoptotic properties, which contribute to a range of health benefits.

METHOD

This review highlights the structural features, physicochemical properties, pharmacokinetics, and therapeutic potential of astaxanthin, particularly focusing on its neuroprotective effects in neurological disorders. To provide a comprehensive overview, we systematically searched published articles across Scopus, Google Scholar, PubMed, and Medline databases from inception to January 1, 2025.

RESULTS

Recent advancements in drug formulation and delivery technologies have enhanced astaxanthin's ability to cross the blood-brain barrier (BBB), significantly increasing its potential as a therapeutic agent for neurological diseases.

CONCLUSION

With its multifaceted biological effects and growing evidence of neuroprotection, astaxanthin shows great promise in the treatment of neurological disorders, particularly stroke. These findings support its future development and application in pharmaceutical strategies aimed at brain health.

Lycopene alleviates cognitive dysfunctions in an Alzheimer's disease rat model via suppressing the oxidative and neuroinflammatory signaling

Oxidative stress and neuroinflammation are key contributors to the development of neurodegenerative disorders, including Alzheimer's disease (AD). Lycopene (LYC) has demonstrated effectiveness in inhibiting inflammatory and oxidative stress markers and appears to exert a modulatory impact on several physiological pathways, behavioral manifestations, and cognitive symptoms associated with AD in animal models. In the present study, an AD model was established in male Wistar albino rats through daily oral administration of hydrated aluminum chloride (AlCl₃·6H₂O) at a dose of 75 mg/kg for six weeks. A Morris water maze (MWM) behavioral test was conducted to confirm memory impairment and cognitive deterioration in the treated rats. Animals exhibiting cognitive dysfunction were subsequently treated with LYC (5 mg/kg orally) for an additional six weeks, followed by a second MWM test before sacrifice. The findings revealed that LYC significantly enhanced performance and cognitive function in the AD model rats and markedly (p < 0.001) reduced the accumulation of amyloid β1-42, proinflammatory mediators [interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α)], malondialdehyde (MDA), and nitrite levels. Furthermore, LYC significantly (p < 0.001) decreased the acetylcholine (ACh) concentration, monoamine oxidase (MAO), creatine kinase (CK), and lactate dehydrogenase (LDH) activites. Additionally, LYC significantly (p < 0.001) increased the acetylcholinesterase (AChE) activity, nuclear factor erythroid-2-related factor 2 (Nrf2), serotonin, anti-inflammatory mediators [transforming growth factor beta-1 (TGF-β1) and interleukin-10 (IL-10)] levels, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities. The therapeutic efficacy of LYC was further supported by improvements in the histopathological appearance of brain tissues, significant (p < 0.001) enhancement of synaptophysin immunohistochemical expression, and suppression of the immunohistochemical expression of cell cycle-related proteins (Ki67 and proliferating cell nuclear antigen [PCNA]). In conclusion, LYC may represent a promising therapeutic agent for AD by targeting multiple pathogenic mechanisms.

Evaluation of the Neurotherapeutic Effect of Quercetin on Neuronal miR-124 and β-Site Amyloid Precursor Protein Cleaving Enzyme 1 (BACE1) in an Experimental Alzheimer's Disease Model

Alzheimer's disease (AD) is the most common cause of dementia, a neurodegenerative disorder that progress overtime, which is best known for mood swings and loss of cognitive, behavioral and functional abilities. Quercetin is one of the most consumed flavonoids in the diet and has neuroprotective, anti-inflammatory and antioxidant effects. The purpose of this study was to assess the potential neurotherapeutic effect of quercetin and compare it with donepezil. 40 Wister male rats were used and separated into two main groups: Group I: control group; Group II: AD group, which was divided into four subgroups: Group IIA: untreated AD-rats; Group IIB: quercetin treated AD-rats; Group IIC: donepezil treated AD-rats and Group IID: combined group of quercetin and donepezil. Hydrated aluminum chloride (AlCl3.6H2O) solution (75 mg/kg/day) was administered orally for 6 weeks to induce the AD-like conditions. Morris water maze, behavior test, was used to monitor the cognitive function. Hippocampal tissues were excised for assessment of Alzheimer's parameters and blood samples were obtained for liver and kidney function assessment. According to the final findings, untreated rats presented significantly increased levels of amyloid β1-42; tau protein; malondialdehyde; nuclear factor kappa-B; acetylcholinesterase activity, β-site amyloid precursor protein cleaving enzyme 1 upregulation and miRNA-124 downregulation. The best results of treatment were observed in the combination of donepezil and quercetin, as revealed by histopathological observations via H&E and Congo red stains. This study led to the conclusion that quercetin, by targeting several pathogenic pathways, could be used as an adjuvant drug with donepezil for AD treatment.

Astaxanthin alleviates fipronil-induced neuronal damages in male rats through modulating oxidative stress, apoptosis, and inflammatory markers

Fipronil (FPN) is an effective pesticide for veterinary and agricultural use; however, it can induce neurotoxic effects on non-target organisms after accidental exposure. Astaxanthin (AST) is a dark red carotenoid with antioxidant, anti-inflammatory, neuroprotective, and antiapoptotic effects. This study investigated the ameliorative impact of AST against FPN-induced brain damage in rats. Thirty-two adult Wistar rats were allocated into four groups (n = 8): Control, AST (20 mg/kg bwt/day), fipronil (FPN) (20 mg/kg bwt/day), and AST + FPN group. Acetylcholine (ACh), dopamine, malondialdehyde (MDA), and proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and inflammatory cytokine cyclooxygenase-2 (COX2) levels were enhanced in the FPN-administered group relative to the control group. In addition, a substantial reduction of acetylcholine esterase (AchE), gamma-aminobutyric acid (GABA), serotonin, reduced glutathione (GSH) levels, catalase (CAT), and total superoxide dismutase (T-SOD) enzyme activities were determined. FPN induced histopathological alterations in the cerebral and cerebellar tissues. Likewise, the histomorphometric image analysis of H and E-stained tissue sections was constant with FPN-induced neurotoxicity. Immunohistochemically, an intense positive immunohistochemical staining of apoptotic marker caspase-3 and astrocytes activation marker glial fibrillary acidic protein (GFAP) in the examined tissues was noticed. Inversely, the simultaneous administration of AST partially attenuated FPN impacts, ameliorating the severity of FPN-induced neuronal damage. These results were also established with the molecular docking findings. It could be suggested that AST has antioxidant, anti-inflammatory, and anti-apoptotic capabilities against FPN-induced neuronal damage via suppression of oxidative stress and pro-inflammatory cytokines, preservation of the neurotransmitters, and the cerebral and cerebellar histoarchitectures.

Effects of memantine and donepezil on social memory, anxiety-like behavior and the expression levels of microRNA-124, microRNA-125b, and microRNA-132 in scopolamine-induced memory impairment in rats

INTRODUCTION

Almost all physiological processes are modulated by microRNAs, therefore, dysregulation of these small regulatory RNAs is observed in a variety of diseases, including cognitive impairments.

METHODS

In this study, 40 male Wistar rats were randomly divided into five groups of control, scopolamine, donepezil, memantine, and combined administration of donepezil + memantine. Rats in scopolamine, donepezil, memantine, and combined administration of donepezil + memantine groups received scopolamine (1 mg/kg-intraperitoneal) for 7 days. After the last administration of scopolamine, was started injecting donepezil (3 mg/kg-i.p.), memantine (10 mg/kg-i.p.), and combined administration of Donepezil + Memantine (0.5 mg/kg and 5 mg/kg-i.p., respectively), up to 21 days. Twenty-four hours after the last injection, elevated plus-maze, social interaction, open field tests, and gene expression analysis of miR-124, miR-125b, and miR-132 in the hippocampus were carried out.

RESULTS

The results of the behavioral tests indicate that donepezil and memantine significantly prevented Scopolamine-induced anxiety, sociability, and social memory decline. The gene expression of selected microRNAs did not significantly differ between the groups.

DISCUSSION

This study revealed that donepezil and memantine effectively prevent synaptic plasticity disruption and cognitive decline induced by scopolamine. Findings indicated that this treatment is unrelated to the expression of the selected microRNAs. The positive effects of memantine and donepezil depend on age, dosages, cognitive task demands, and possibly the length and timing of the treatment.

Coenzyme Q10 alleviates AlCl3 and D-galactose induced Alzheimer via modulating oxidative burden and TLR-4/MAPK pathways and regulation microRNA in rat brain

Alzheimer's disease (ad) is the most progressive form of neurodegenerative disease resulting in cognitive and non-cognitive deficits. Coenzyme Q10 (CoQ10) is an anti-inflammatory and anti-oxidative stress supplement that can improve inflammation and oxidative stress associated with ad. This study aimed to explore the protective potential of coenzyme Q10 (CoQ10). It also sought to uncover any synergistic effects when combined with donepezil, an acetylcholinesterase inhibitor, in treating Alzheimer's disease in rats, focusing on the modulation of the TLR-4/MAPK pathway and regulation of microRNA. The experiment involved seventy rats categorized into different groups: control, Reference group (donepezil 10 mg/kg/P.O.), CoQ10 alone (1,200 mg/kg/P.O.), ad-model (D-galactose (120 mg/kg/i.p) + Alcl3 (50 mg/kg/P.O.)), donepezil co-treatment, CoQ10 co-treatment, and CoQ10 + donepezil co-treatment. Behavioral parameter was defined using the Morris-Maze test (MMT) and various assessments, such as GABA, oxidative stress, Aβ1-42, ion homeostasis, toll-like receptor-4 (TLR-4), mitogen-activated protein kinase-1 (MAPK-1), micro-RNA (mir-106b, mir-107, and mir-9) were measured. Immunohistological staining was used to assess structural abnormalities in hippocampus. CoQ10 treatment demonstrated memory improvement, enhanced locomotion, and increased neuronal differentiation, mainly through the activation of the TLR-4/MAPK pathway and regulation of mir-106b, mir-107, and mir-9.

Highlights

Coenzyme Q10 (CoQ10) improved the rats' passive avoidance memory impairment caused by D-gal and AlCl3. ad led to the alteration of the TLR-4/MAPK pathways.CoQ10 as a protective agent, diminishes oxidative burden, improve ion homeostasis.CoQ10 counteracts Alzheimer's disease by enhancing neurotransmitter parameter and regulating the MicroRNA.CoQ10 lowered accumulation of Aβ plaque in the hippocampal neurons of D-Gal and AlCl3-treated rats.One promising therapeutic method was the combination of donepezil and CoQ10 therapy.

Phikud navakot extract acts as an ER stress inhibitor to ameliorate ER stress and neuroinflammation

The prevalence of neurological disorders (NDs) such as Alzheimer's disease (AD) is increasing globally, and the lack of effective pharmacological interventions presents a significant health risk. Multiple mechanisms including the activation of oxidative stress, amyloid pathway, ER stress, and neuroinflammation have been implicated in AD; therefore, multi-targeted agents against these mechanisms may be preferable to single-target agents. Phikud Navakot (PN), a Thai traditional medicine combining nine herbs, has been shown to reduce oxidative stress and neuroinflammation of neuronal and microglia cells and the coculture between them, indicating the promising role of PN extract as anti-AD. This study evaluated the neuroprotective effects of PN extract against oxidative stress, amyloid pathway, endoplasmic reticulum stress (ER stress), and neuroinflammation using neuronal and microglia cells, as well as in a Drosophila model of AD. Results showed that PN extract reduced oxidative stress, lipid peroxidation, pro-inflammatory cytokines, amyloid pathway, and ER stress induced by aluminum chloride (AlCl3, AD-induced agent) or thapsigargin (TG, an ER stress activator) in both neurons and microglia cells. PN extract also reduced oxidative stress, ER-stress-related genes, and neurotoxic peptides (amyloid beta) in a Drosophila model of AD. Data indicated that PN extract may function as an anti-AD agent by targeting multiple mechanisms as described. This research also revealed for the first time that PN extract acted as an ER stress inhibitor.

Epigenetic Mechanisms of Aluminum-Induced Neurotoxicity and Alzheimer's Disease: A Focus on Non-Coding RNAs

Aluminum (Al) is known to induce neurotoxic effects, potentially contributing to Alzheimer's disease (AD) pathogenesis. Recent studies suggest that epigenetic modification may contribute to Al neurotoxicity, although the mechanisms are still debatable. Therefore, the objective of the present study was to summarize existing data on the involvement of epigenetic mechanisms in Al-induced neurotoxicity, especially AD-type pathology. Existing data demonstrate that Al exposure induces disruption in DNA methylation, histone modifications, and non-coding RNA expression in brains. Alterations in DNA methylation following Al exposure were shown to be mediated by changes in expression and activity of DNA methyltransferases (DNMTs) and ten-eleven translocation proteins (TETs). Al exposure was shown to reduce histone acetylation by up-regulating expression of histone deacetylases (HDACs) and impair histone methylation, ultimately contributing to down-regulation of brain-derived neurotrophic factor (BDNF) expression and activation of nuclear factor κB (NF-κB) signaling. Neurotoxic effects of Al exposure were also associated with aberrant expression of non-coding RNAs, especially microRNAs (miR). Al-induced patterns of miR expression were involved in development of AD-type pathology by increasing amyloid β (Aβ) production through up-regulation of Aβ precursor protein (APP) and β secretase (BACE1) expression (down-regulation of miR-29a/b, miR-101, miR-124, and Let-7c expression), increasing in neuroinflammation through NF-κB signaling (up-regulation of miR-9, miR-125b, miR-128, and 146a), as well as modulating other signaling pathways. Furthermore, reduced global DNA methylation, altered histone modification, and aberrant miRNA expression were associated with cognitive decline in Al-exposed subjects. However, further studies are required to evaluate the contribution of epigenetic mechanisms to Al-induced neurotoxicity and/or AD development.

A marine-derived antioxidant astaxanthin as a potential neuroprotective and neurotherapeutic agent: A review of its efficacy on neurodegenerative conditions

Astaxanthin is a potent lipid-soluble carotenoid produced by several different freshwater and marine microorganisms, including microalgae, bacteria, fungi, and yeast. The proven therapeutic effects of astaxanthin against different diseases have made this carotenoid popular in the nutraceutical market and among consumers. Recently, astaxanthin is also receiving attention for its effects in the co-adjuvant treatment or prevention of neurological pathologies. In this systematic review, studies evaluating the efficacy of astaxanthin against different neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, cerebrovascular diseases, and spinal cord injury are analyzed. Based on the current literature, astaxanthin shows potential biological activity in both in vitro and in vivo models. In addition, its preventive and therapeutic activities against the above-mentioned diseases have been emphasized in studies with different experimental designs. In contrast, none of the 59 studies reviewed reported any safety concerns or adverse health effects as a result of astaxanthin supplementation. The preventive or therapeutic role of astaxanthin may vary depending on the dosage and route of administration. Although there is a consensus in the literature regarding its effectiveness against the specified diseases, it is important to determine the safe intake levels of synthetic and natural forms and to determine the most effective forms for oral intake.

Natural Antioxidants: An Effective Strategy for the Treatment of Alzheimer's Disease at the Early Stage

The critical role of oxidative stress in Alzheimer's disease (AD) has been recognized by researchers recently, and natural antioxidants have been demonstrated to have anti-AD activity in animal models, such as Ginkgo biloba extract, soy isoflavones, lycopene, and so on. This paper summarized these natural antioxidants and points out that natural antioxidants always have multiple advantages which are help to deal with AD, such as clearing free radicals, regulating signal transduction, protecting mitochondrial function, and synaptic plasticity. Based on the available data, we have created a relatively complete pathway map of reactive oxygen species (ROS) and AD-related targets and concluded that oxidative stress caused by ROS is the core of AD pathogenesis. In the prospect, we introduced the concept of a combined therapeutic strategy, termed "Antioxidant-Promoting Synaptic Remodeling," highlighting the integration of antioxidant interventions with synaptic remodeling approaches as a novel avenue for therapeutic exploration.

Astaxanthin alleviates ganglioside metabolism disorder in the cortex of Alzheimer's disease mice

The present study analyzed the amelioration effect and mechanism of two kinds of astaxanthin (AST), including free-AST (F-AST) and docosahexaenoic acid-acylated AST monoester (AST-DHA), on ganglioside (GLS) metabolism in the cortex of APP/PS1 mice using the LC-MS strategy in combination with molecular biology. Water maze and immunohistochemical experiments demonstrated that AST significantly improved the cognitive level of APP/PS1 mice and reduced Aβ deposition in the cortex. After the dietary intake of AST, the composition and level of 84 GLS molecular species in the mouse cortex were determined using the LC-MS strategy. The results showed that the total GLS was reduced, most complex GLS was decreased, and simple GLS (GM3 and GM1a) was increased in the APP/PS1 mouse cortex. Notably, F-AST mainly regulated complex GLS (p < 0.001), whereas AST-DHA primarily reacted with simple GLS (p < 0.001). OAc-GQ1a(38:1), OAc-GQ1a(36:1), GD1a(36:1), and GM3(38:1) decreased 3.73, 2.31, and 2.29-fold and increased 3.54-fold, respectively, and were identified as potential AD biomarkers in the cortices of APP/PS1 mice. Additionally, the AST diet significantly upregulated the mRNA expression of GLS synthesizing genes (st3gal5, st8sia1, b3galt4, st3fal2, and soat) and siae (p < 0.05) and down-regulated that of the GLS catabolizing gene hexa (p < 0.01). In conclusion, improving GLS homeostasis in the AD mouse cortex might be a critical pathway to explain the AD-preventing effect of AST.

Astaxanthin impact on brain: health potential and market perspective

Nowadays, there is an emergent interest in new trend-driven biomolecules to improve health and wellbeing, which has become an interesting and promising field, considering their high value and biological potential. Astaxanthin is one of these promising biomolecules, with impressive high market growth, especially in the pharmaceutical and food industries. This biomolecule, obtained from natural sources (i.e., microalgae), has been reported in the literature to have several beneficial health effects due to its biological properties. These benefits seem to be mainly associated with Astaxanthin's high antioxidant and anti-inflammatory properties, which may act on several brain issues, thus attenuating symptoms. In this sense, several studies have demonstrated the impact of astaxanthin on a wide range of diseases, namely on brain disorders (such as Alzheimer's disease, Parkinson, depression, brain stroke and autism). Therefore, this review highlights its application in mental health and illness. Furthermore, a S.W.O.T. analysis was performed to display an approach from the market/commercial perspective. However, to bring the molecule to the market, there is still a need for more studies to increase deep knowledge regarding the real impact and mechanisms in the human brain.HIGHLIGHTSAstaxanthin has been mainly extracted from the algae Haematococcus pluvialisAstaxanthin, bioactive molecule with high antioxidant and anti-inflammatory propertiesAstaxanthin has an important protective effect on brain disordersAstaxanthin is highly marketable, mainly for food and pharmaceutical industries.

Natural antioxidants that act against Alzheimer's disease through modulation of the NRF2 pathway: a focus on their molecular mechanisms of action

Characterized by a complex pathophysiology that includes the intraneuronal formation of neurofibrillary tangles and the extracellular deposition of β-amyloid plaques, Alzheimer's disease (AD) is a terminal neurodegenerative disease that causes dementia in older adults. Oxidative stress in the brain is considered as one of the contributing factors to the pathogenesis of AD, and thus, antioxidants have attracted much interest as potential therapeutic agents against the disorder. Natural antioxidants are typically characterized by low acute and chronic toxicity, which facilitates their potential therapeutic application. One important molecular target for the beneficial effects of natural antioxidants is the nuclear factor erythroid-derived 2-related factor 2 (NFE2L2/NRF2). NRF2 is a key transcription factor that orchestrates the cellular antioxidant response through regulating the expression of oxidative stress-related genes harboring the antioxidant response element (ARE) in their promoters. Indeed, in the case of excessive oxidative damage, NRF2 migrates to the nucleus and binds to ARE, activating the transcription of antioxidant protector genes. There is increasing evidence that NRF2 is implicated in AD pathology through dysfunction and altered localization, which renders it as a potential therapeutic target for AD. Thus, this review summarizes the most recent (2018-2023) advances on the NRF2-modulating activity of natural antioxidants observed in vitro and in AD animal models. This information will help elucidate the molecular mechanisms governing the antioxidant activity of such phytochemicals to highlight their therapeutic potential against common neurodegenerative diseases, such as AD.

Nose to Brain Delivery of Astaxanthin–Loaded Nanostructured Lipid Carriers in Rat Model of Alzheimer’s Disease: Preparation, in vitro and in vivo Evaluation

Background

Astaxanthin (AST) is a second-generation antioxidant with anti-inflammatory and neuroprotective properties and could be a promising candidate for Alzheimer's disease (AD) therapy, but is shows poor oral bioavailability due to its high lipophilicity.

Purpose

This study aimed to prepare and evaluate AST-loaded nanostructured lipid carriers (NLCs), for enhanced nose-to-brain drug delivery to improve its therapeutic efficacy in rat model of AD.

Methods

AST-NLCs were prepared using hot high-pressure homogenization technique, and processing parameters such as total lipid-to-drug ratio, solid lipid-to-liquid lipid ratio, and concentration of surfactant were optimized.

Results

The optimized AST-NLCs had a mean particle size of 142.8 ± 5.02 nm, polydispersity index of 0.247 ± 0.016, zeta potential of -32.2 ± 7.88 mV, entrapment efficiency of 94.1 ± 2.46%, drug loading of 23.5 ± 1.48%, and spherical morphology as revealed by transmission electron microscopy. Differential scanning calorimetry showed that AST was molecularly dispersed in the NLC matrix in an amorphous state, whereas Fourier transform infrared spectroscopy indicated that there is no interaction between AST and lipids. AST displayed a biphasic release pattern from NLCs; an initial burst release followed by sustained release for 24 h. AST-NLCs were stable at 4-8 ±2°C for six months. Intranasal treatment of AD-like rats with the optimized AST-NLCs significantly decreased oxidative stress, amyloidogenic pathway, neuroinflammation and apoptosis, and significantly improved the cholinergic neurotransmission compared to AST-solution. This was observed by the significant decline in the levels of malondialdehyde, nuclear factor-kappa B, amyloid beta (Aβ_1‑42), caspase-3, acetylcholinesterase, and β-site amyloid precursor protein cleaving enzyme-1 expression, and significant increase in the contents of acetylcholine and glutathione after treatment with AST-NLCs.

Conclusion

NLCs enhanced the intranasal delivery of AST and significantly improved its therapeutic properties.

Molecular Mechanisms Involved in the Regulation of Neurodevelopment by miR-124

miR-124 is a miRNA predominantly expressed in the nervous system and accounts for more than a quarter of the total miRNAs in the brain. It regulates neurogenesis, neuronal differentiation, neuronal maturation, and synapse formation and is the most important miRNA in the brain. Furthermore, emerging evidence has suggested miR-124 may be associated with the pathogenesis of various neurodevelopmental and neuropsychiatric disorders. Here, we provide an overview of the role of miR-124 in neurodevelopment and the underling mechanisms, and finally, we prospect the significance of miR-124 research to the field of neuroscience.

Multiple roles of fucoxanthin and astaxanthin against Alzheimer's disease: Their pharmacological potential and therapeutic insights

Alzheimer's disease (AD) is the most devastating neurodegenerative disorder affecting the elderly. The exact pathology of AD is not yet fully understood and several hallmarks such as the deposition of amyloid-β, tau hyperphosphorylation, and neuroinflammation, as well as mitochondrial, metal ions, autophagy, and cholinergic dysfunctions are known as pathologic features of AD. Since no definitive treatment has been proposed to target AD to date, many natural products have shown promising preventive potentials and contributed to slowing down the disease progression. Algae is a promising source of novel bioactive substances known to prevent neurodegenerative disorders including AD. In this context, fucoxanthin and astaxanthin, natural carotenoids abundant in algae, has shown to possess neuroprotective properties through antioxidant, and anti-inflammatory characteristics in modulating the symptoms of AD. Fucoxanthin and astaxanthin exhibit anti-AD activities by inhibition of AChE, BuChE, BACE-1, and MAO, suppression of Aβ accumulation. Also, fucoxanthin and astaxanthin inhibit apoptosis induced by Aβ_1-42 and H₂O₂-induced cytotoxicity, and modulate the antioxidant enzymes (SOD and CAT), through inhibition of the ERK pathway. Moreover, cellular and animal studies on the beneficial effects of fucoxanthin and astaxanthin against AD were also reviewed. The potential role of fucoxanthin and astaxanthin exhibits great efficacy for the management of AD by acting on multiple targets.

Targeting Novel microRNAs in Developing Novel Alzheimer's Disease Treatments

Alzheimer's disease (AD) is considered a multifactorial disease and a significant cause of dementia during aging. This neurodegenerative disease process is classically divided into two different pathologies cerebral accumulation of amyloid-β and hyperphosphorylated neurofibrillary tau tangles. In recent years, massive efforts have been made to treat AD by decreasing amyloid-β and tau in the brains of patients with AD, with no success. The dysfunction of a wide range of microRNAs promotes the generation and insufficient clearance of amyloid-β (Aβ) and increases tau plaques which are the pathophysiological markers of AD. Disturbance of these microRNAs is associated with mitochondrial dysfunction, oxidative damage, inflammation, apolipoprotein E4 (APOE4) pathogenic process, synaptic loss, and cognitive deficits induced by AD. Targeting a specific microRNA to restore AD-induced impairments at multiple stages might provide a promising approach for developing new drugs and therapeutic strategies for patients with AD. This review focuses on different mechanisms of microRNAs in AD pathophysiology.

The Putative Role of Astaxanthin in Neuroinflammation Modulation: Mechanisms and Therapeutic Potential

Neuroinflammation is a protective mechanism against insults from exogenous pathogens and endogenous cellular debris and is essential for reestablishing homeostasis in the brain. However, excessive prolonged neuroinflammation inevitably leads to lesions and disease. The use of natural compounds targeting pathways involved in neuroinflammation remains a promising strategy for treating different neurological and neurodegenerative diseases. Astaxanthin, a natural xanthophyll carotenoid, is a well known antioxidant. Mounting evidence has revealed that astaxanthin is neuroprotective and has therapeutic potential by inhibiting neuroinflammation, however, its functional roles and underlying mechanisms in modulating neuroinflammation have not been systematically summarized. Hence, this review summarizes recent progress in this field and provides an update on the medical value of astaxanthin. Astaxanthin modulates neuroinflammation by alleviating oxidative stress, reducing the production of neuroinflammatory factors, inhibiting peripheral inflammation and maintaining the integrity of the blood-brain barrier. Mechanistically, astaxanthin scavenges radicals, triggers the Nrf2-induced activation of the antioxidant system, and suppresses the activation of the NF-κB and mitogen-activated protein kinase pathways. With its good biosafety and high bioavailability, astaxanthin has strong potential for modulating neuroinflammation, although some outstanding issues still require further investigation.

Discovery of New 1,3,4-Oxadiazoles with Dual Activity Targeting the Cholinergic Pathway as Effective Anti-Alzheimer Agents

Finding an effective anti-Alzheimer agent is quite challenging due to its multifactorial nature. As such, multitarget directed ligands (MTDLs) could be a promising paradigm for finding potential therapeutically effective new small-molecule bioactive agents against Alzheimer's disease (AD). We herein present the design, synthesis, and biological evaluation of a new series of compounds based on a 5-pyrid-3-yl-1,3,4-oxadiazole scaffold. Our synthesized compounds displayed excellent in vitro enzyme inhibitory activity at nanomolar (nM) concentrations against two major AD disease-modifying targets, i.e., acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Among our compounds, 5e was considered the best dual inhibitor of both AChE (IC50 = 50.87 nM) and BuChE (IC50 = 4.77 nM), where these values surpassed those of rivastagmine (the only FDA-approved dual AChE and BuChE inhibitor) in our study. Furthermore, in vivo and ex vivo testing of the hit compound 5e highlighted its significant AD-biotargeting effects including reducing the elevated levels of lipid peroxidation and glutathione (GSH), normalizing levels of 8-OHdG, and, most importantly, decreasing the levels of the well-known AD hallmark β-amyloid protein. Finally, the binding ability of 5e to each of our targets, AChE and BuChE, was confirmed through additional molecular docking and molecular dynamics (MD) simulations that reflected good interactions of 5e to the active site of both targets. Hence, we herein present a series of new 1,3,4-oxadiazoles that are promising leads for the development of dual-acting AChE and BuChE inhibitors for the management of AD.

Molecular Mechanisms of Astaxanthin as a Potential Neurotherapeutic Agent

Neurological disorders are diseases of the central and peripheral nervous system that affect millions of people, and the numbers are rising gradually. In the pathogenesis of neurodegenerative diseases, the roles of many signaling pathways were elucidated; however, the exact pathophysiology of neurological disorders and possible effective therapeutics have not yet been precisely identified. This necessitates developing multi-target treatments, which would simultaneously modulate neuroinflammation, apoptosis, and oxidative stress. The present review aims to explore the potential therapeutic use of astaxanthin (ASX) in neurological and neuroinflammatory diseases. ASX, a member of the xanthophyll group, was found to be a promising therapeutic anti-inflammatory agent for many neurological disorders, including cerebral ischemia, Parkinson's disease, Alzheimer's disease, autism, and neuropathic pain. An effective drug delivery system of ASX should be developed and further tested by appropriate clinical trials.