Neuroprotective effects of some seaweeds against Zn - induced neuronal damage in HT-22 cells via modulation of redox imbalance, inhibition of apoptosis and acetylcholinesterase activity

The neuroprotective effects of ferulic acid in toxin-induced models of Parkinson's disease: A review

Parkinson's disease is predominantly caused by dopaminergic neuron loss in the substantia nigra pars compacta and the accumulation of alpha-synuclein protein. Though the general consensus is that several factors, such as aging, environmental factors, mitochondrial dysfunction, accumulations of neurotoxic alpha-synuclein, malfunctions of the lysosomal and proteasomal protein degradation systems, oxidative stress, and neuroinflammation, are involved in the neurodegeneration process of Parkinson's disease, the precise mechanism by which all of these factors are triggered remains unknown. Typically, neurotoxic compounds such as rotenone, 6-hydroxydopamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl 4-phenyl pyridinium (mpp+), paraquat, and maneb are used to Preclinical models of Parkinson's disease Ferulic acid is often referred to by its scientific name, 4-hydroxy-3-methoxycinnamic acid (C10H10O4), and is found naturally in cereals, fruits, vegetables, and bee products. This substance exhibits neuroprotective effects against Parkinson's disease because of its intriguing potential, which includes anti-inflammatory and antioxidant qualities. This review goes into additional detail about Parkinson's disease and the neuroprotective properties of ferulic acid that may help prevent the condition.

Roasted cashew (Anacardium occidentale L.) nut-enhanced diet forestalls cisplatin-initiated brain harm in rats

The incessant dose constraining symptom of the chemotherapeutic agent, cisplatin is neurotoxicity. This examination tried to explore the neuroprotective impact of roasted cashew nut-enhanced diet against brain deficits related with treatment with cisplatin. Rats were separated in to six groups: Control, CIS (cisplatin [7 mg/kg body weight, i.p]), CIS +10% CN (cisplatin plus 10% roasted cashew nut), CIS +20% CN (cisplatin plus 20% roasted cashew nut), 10% CN (10% roasted cashew nut) and 20% CN (20% roasted cashew nut) for 28 days. Key enzymes associated with brain function, including cholinesterases (AChE and BChE), monoaminergic enzyme (MAO), arginase, and adenosine deaminase (ADA), were investigated after the treatment. The following oxidative stress indicators were also measured in the rat brain: glutathione-S-transferase (GST), glutathione peroxidase (GPx), total antioxidant capacity (TAC), total thiol (T-SH), non-protein thiol (NPSH), thiobarbituric acid reactive substances (TBARS), reactive oxygen species (ROS), nitric oxide (NO), superoxide dismutase (SOD). Our outcomes demonstrated that roasted cashew nut enhanced diet showed inhibitory impact on activities of AChE, BChE, ADA, MAO and arginase in cisplatin-induced rats. The roasted cashew nut supplemented diet also boosted redox equilibrium and displayed protection against cispaltin-induced oxidative damage to rats' brains by an increase in SOD, CAT, GST and GPx activities, TAC, T-SH, NPSH and NO levels as well as a considerable drop in ROS and RBARS levels. Roasted cashew nut enhanced diet additionally forestalled neuronal degeneration in rat brain. Thus, roasted cashew nuts could be used as a nutraceutical or functional food to treat cisplatin-induced neurotoxicity.

Practical applications

The results show that increasing roasted cashew nut consumption can significantly improve antioxidant status, reduce lipid peroxidation, and suppress cholinesterase, adenosine deaminase, monoamine oxidase, and arginase activities in the brain under cisplatin-induced circumstances.

Neuroprotective effects of ergosterol against TNF-α-induced HT-22 hippocampal cell injury

Neuroinflammation is a brain pathology that involves the expression of high levels of pro-inflammatory mediators, including tumor necrosis factor-alpha (TNF-α). An excessive TNF-α expression could result in neuronal cell death and subsequently lead to neurodegeneration. Auricularia polytricha (AP; an edible mushroom) has been reported as a rich source of ergosterol with several medicinal benefits. The current study reports on the neuroprotective effects of AP extracts and ergosterol against the TNF-α-induced HT-22 hippocampal cell injury. The hexane extract of AP (APH) demonstrated a neuroprotective effect against the TNF-α-induced HT-22 cell toxicity, taking place through the activation of the antioxidant pathway. Ergosterol, a major component of APH, could attenuate the toxicity of TNF-α on HT-22 cells, by increasing the expression of a major antioxidant enzyme (superoxide dismutase-1) and by facilitating the scavenging of reactive oxygen species through antioxidant signaling. Moreover, an antibody array was performed to screen the possible molecular targets of ergosterol in HT-22 cells exposed to TNF-α. Based on the antibody array, the phospho-Akt was activated in the presence of ergosterol, and this finding was also supported by Western blotting analysis. Furthermore, ergosterol inhibited the transcriptional expressions of the glutamate ionotropic receptor N-methyl-D-aspartate (NMDA) type subunit 2B gene (Grin2b) through an early growth response-1 (EGR-1) overexpression in TNF-α-treated HT-22 cells. Our findings suggest that a novel therapeutic effect of AP and ergosterol against neuroinflammation, that it is mediated by an NMDA gene modulation occurring through the overexpression of the EGR-1 transcription factor.

Biological Potential, Gastrointestinal Digestion, Absorption, and Bioavailability of Algae-Derived Compounds with Neuroprotective Activity: A Comprehensive Review

Currently, there is no known cure for neurodegenerative disease. However, the available therapies aim to manage some of the symptoms of the disease. Human neurodegenerative diseases are a heterogeneous group of illnesses characterized by progressive loss of neuronal cells and nervous system dysfunction related to several mechanisms such as protein aggregation, neuroinflammation, oxidative stress, and neurotransmission dysfunction. Neuroprotective compounds are essential in the prevention and management of neurodegenerative diseases. This review will focus on the neurodegeneration mechanisms and the compounds (proteins, polyunsaturated fatty acids (PUFAs), polysaccharides, carotenoids, phycobiliproteins, phenolic compounds, among others) present in seaweeds that have shown in vivo and in vitro neuroprotective activity. Additionally, it will cover the recent findings on the neuroprotective effects of bioactive compounds from macroalgae, with a focus on their biological potential and possible mechanism of action, including microbiota modulation. Furthermore, gastrointestinal digestion, absorption, and bioavailability will be discussed. Moreover, the clinical trials using seaweed-based drugs or extracts to treat neurodegenerative disorders will be presented, showing the real potential and limitations that a specific metabolite or extract may have as a new therapeutic agent considering the recent approval of a seaweed-based drug to treat Alzheimer’s disease.

Role of Cholinergic Signaling in Alzheimer's Disease

Acetylcholine, a neurotransmitter secreted by cholinergic neurons, is involved in signal transduction related to memory and learning ability. Alzheimer’s disease (AD), a progressive and commonly diagnosed neurodegenerative disease, is characterized by memory and cognitive decline and behavioral disorders. The pathogenesis of AD is complex and remains unclear, being affected by various factors. The cholinergic hypothesis is the earliest theory about the pathogenesis of AD. Cholinergic atrophy and cognitive decline are accelerated in age-related neurodegenerative diseases such as AD. In addition, abnormal central cholinergic changes can also induce abnormal phosphorylation of ttau protein, nerve cell inflammation, cell apoptosis, and other pathological phenomena, but the exact mechanism of action is still unclear. Due to the complex and unclear pathogenesis, effective methods to prevent and treat AD are unavailable, and research to explore novel therapeutic drugs is various and active in the world. This review summaries the role of cholinergic signaling and the correlation between the cholinergic signaling pathway with other risk factors in AD and provides the latest research about the efficient therapeutic drugs and treatment of AD.

Natural Polysaccharides as Preventive and Therapeutic Horizon for Neurodegenerative Diseases

Neurodegenerative diseases are a serious and widespread global public health burden amongst aging populations. The total estimated worldwide global cost of dementia was US$818 billion in 2015 and has been projected to rise to 2 trillion US$ by 2030. While advances have been made to understand different neurodegenerative disease mechanisms, effective therapeutic strategies do not generally exist. Several drugs have been proposed in the last two decades for the treatment of different types of neurodegenerative diseases, with little therapeutic benefit, and often with severe adverse and side effects. Thus, the search for novel drugs with higher efficacy and fewer drawbacks is an ongoing challenge in the treatment of neurodegenerative disease. Several natural compounds including polysaccharides have demonstrated neuroprotective and even therapeutic effects. Natural polysaccharides are widely distributed in plants, animals, algae, bacterial and fungal species, and have received considerable attention for their wide-ranging bioactivity, including their antioxidant, anti-neuroinflammatory, anticholinesterase and anti-amyloidogenic effects. In this review, we summarize different mechanisms involved in neurodegenerative diseases and the neuroprotective effects of natural polysaccharides, highlighting their potential role in the prevention and therapy of neurodegenerative disease.

Dual prophylactic/therapeutic potential of date seed, and nigella and olive oils-based nutraceutical formulation in rats with experimentally-induced Alzheimer's disease: A mechanistic insight

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with a multifactorial etiology and significantly increasing incidence during the last decade. Hence, developing an effective therapy is crucial for public health. The current study aimed to examine the dual prophylactic/therapeutic potential of a nutraceutical formula based on aqueous extract of roasted date seeds, and nigella and virgin-olive oils against experimentally-induced Alzheimer's disease in rats. Alzheimer's disease-like pathology was induced in male Wistar rats using oral CuSO₄ (200 mg/Kg/day for two months). The nutraceutical formula was given orally to experimental animals (10 mL/kg/d) for 14 days before (as prophylaxis) and after Alzheimer's disease induction and its therapeutic effect in both cases is tested in comparison to donepezil (0.5 mg/kg/d). The nutraceutical formula was found to ameliorate the CuSO₄-induced neuronal damage and regenerate the affected hippocampus tissue and significantly improvemed in learning ability. The formula was also effective in decreasing brain amyloid-β, tau protein, TNF-α level, iNOS level in hippocampus, oxidative stress level, and inhibiting acetylcholinesterase activity and expression in brain and hippocampus, respectively. Further, an increase in GSH levels, activities of SOD, and GST and levels of hippocampus ADAM 17 and brain phospholipids was observed. In conclusion, the studied nutraceutical formula is proved to be effective in ameliorating Alzheimer's neurodegenerative progression with added-prophylactic potential.

Sulfated polysaccharides of some seaweeds exhibit neuroprotection via mitigation of oxidative stress, cholinergic dysfunction and inhibition of Zn - induced neuronal damage in HT-22 cells

Background

Sulfated polysaccharides from marine algae are known to possess antioxidative activities, however, their therapeutic role in metal-induced neurodegeneration has not been explored. In this study, the neuroprotective potentials of sulfated polysaccharides isolated from Ecklonia maxima (PKPM), Gelidium pristoides (PMNP), Ulva lactuca (PULV), Ulva rigida (PURL) and Gracilaria gracilis (PGCL) against Zn-induced neurodegeneration in rats’ hippocampal neuronal cells (HT-22) were assessed.

Methods

Cells were cultured and maintained at 37 °C. Control cells did not contain Zinc sulphate (ZnSO₄) while other experimental groups contain Zn (50 μM) alone or in combination with sulfated polysaccharides (0.4 or 0.8 mg/mL). Cell viability was assessed using MTT assay while apoptotic assay was also determined using acridine orange and ethidium bromide staining technique. Oxidative stress parameters (superoxide dismutase and catalase activities, glutathione and nitric oxide levels) and acetylcholinesterase activity were also assessed in neuronal cells treated with or without Zn.

Results

Zn significantly reduced cell viability to about 50%. However, sulfated polysaccharides improved cell viability to about 95%. The sulfated polysaccharides also prevented late apoptosis and necrosis triggered by Zn. Furthermore, superoxide dismutase and catalase activities including glutathione content were significantly low in cells induced with Zn. Treatment with sulfated polysaccharides triggered a significant increase in antioxidant enzymes and glutathione content as well as a decrease in the activity of acetylcholinesterase in cells treated with Zn.

Conclusion

PKPM, PGCL, PURL, PULV and PMNP exhibit neuroprotective effects against neuronal damage induced by Zn and this may be attributed to inhibition of apoptosis, oxidative damage and acetylcholinesterase activity. These polysaccharides may be good therapeutic agents to protect neuronal cells against Zn - induced pathological processes associated with Alzheimer’s disease.

Neuroprotective Effect of Carotenoid-Rich Enteromorpha prolifera Extract via TrkB/Akt Pathway against Oxidative Stress in Hippocampal Neuronal Cells

In this study, we found that E. prolifera extract (EAEP) exhibits neuroprotective effects in oxidative stress-induced neuronal cells. EAEP improved cell viability as well as attenuated the formation of intracellular reactive oxygen species (ROS) and apoptotic bodies in glutamate-treated hippocampal neuronal cells (HT-22). Furthermore, EAEP improved the expression of brain-derived neurotrophic factor (BDNF) and antioxidant enzymes such as heme oxygenase-1 (HO-1), NAD(P)H quinine oxidoreductase-1 (NQO-1), and glutamate-cysteine ligase catalytic subunit (GCLC) via the tropomyosin-related kinase receptor B/ protein kinase B (TrkB/Akt) signaling pathway. In contrast, the pre-incubation of K252a, a TrkB inhibitor, or MK-2206, an Akt-selective inhibitor, ameliorated the neuroprotective effects of EAEP in oxidative stress-induced neuronal cells. These results suggest that EAEP protects neuronal cells against oxidative stress-induced apoptosis by upregulating the expression of BDNF and antioxidant enzymes via the activation of the TrkB/Akt pathway. In conclusion, such an effect of EAEP, which is rich in carotenoid-derived compounds, may justify its application as a food supplement in the prevention and treatment of neurodegenerative disorders.

Curcumin Administration Mitigates Cyclophosphamide-Induced Oxidative Damage and Restores Alteration of Enzymes Associated with Cognitive Function in Rats' Brain

The use of chemotherapeutic drugs is associated with oxidative damage, cognitive dysfunction, and brain damage. This study sought to investigate the neuroprotective effect of curcumin against cognitive problems associated with treatment with cyclophosphamide via assessment of biomolecules associated with cognitive function in rats' brain homogenates. Rats were divided in to five groups: Control (vehicle), CUR (curcumin [20 mg/kg]), CPA (cyclophosphamide [150 mg/kg]), CUR1 + CPA (curcumin [20 mg/kg] and cyclophosphamide [150 mg/kg]), and CPA + CUR2 (cyclophosphamide [150 mg/kg] and curcumin [20 mg/kg]). After the treatment, cognitive behavior was assessed and enzymes [cholinesterases, purinergic enzymes, arginase, and angiotensin I-converting enzyme] associated with cognitive function were examined. Oxidative stress parameters [total thiol, non-protein thiol, malondialdehyde, and nitric oxide] including the expression of caspase-3 were also assessed in rats' brain. Our results showed that curcumin improved cognitive behavior, attenuated cholinergic deficit as revealed by the inhibition of cholinesterases, and improved purinergic signaling in cyclophosphamide-treated rats. Furthermore, curcumin reduced angiotensin-I-converting enzyme and arginase activities before and after treatment with cyclophosphamide. Curcumin also improved redox balance and showed protection against cyclophosphamide-induced oxidative damage to rats' brain via an increase in protein and non-protein thiols and nitric oxide levels as well as a significant reduction in malondialdehyde levels. Curcumin also prevented neuronal degeneration in different brain regions and reduced caspase-3 expression. Hence this study suggests that pre and post-treatment with curcumin improved neurobehavior, modulates some biomarkers associated with cognitive function and exhibit neuroprotection against cyclophosphamide-induced neurotoxicity in rats.

Macroalgae as a Valuable Source of Naturally Occurring Bioactive Compounds for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a neurological condition that affects mostly aged individuals. Evidence suggests that pathological mechanisms involved in the development of AD are associated with cholinergic deficit, glutamate excitotoxicity, beta-amyloid aggregation, tau phosphorylation, neuro-inflammation, and oxidative damage to neurons. Currently there is no cure for AD; however, synthetic therapies have been developed to effectively manage some of the symptoms at the early stage of the disease. Natural products from plants and marine organisms have been identified as important sources of bioactive compounds with neuroprotective potentials and less adverse effects compared to synthetic agents. Seaweeds contain several kinds of secondary metabolites such as phlorotannins, carotenoids, sterols, fucoidans, and poly unsaturated fatty acids. However, their neuroprotective effects and mechanisms of action have not been fully explored. This review discusses recent investigations and/or updates on interactions of bioactive compounds from seaweeds with biomarkers involved in the pathogenesis of AD using reports in electronic databases such as Web of science, Scopus, PubMed, Science direct, Scifinder, Taylor and Francis, Wiley, Springer, and Google scholar between 2015 and 2019. Phlorotannins, fucoidans, sterols, and carotenoids showed strong neuroprotective potentials in different experimental models. However, there are no data from human studies and/or clinical trials.