Pretreated fucoidan confers neuroprotection against transient global cerebral ischemic injury in the gerbil hippocampal CA1 area via reducing of glial cell activation and oxidative stress

Porphyran Attenuates Neuronal Loss in the Hippocampal CA1 Subregion Induced by Ischemia and Reperfusion in Gerbils by Inhibiting NLRP3 Inflammasome-Mediated Neuroinflammation

Porphyran, a sulfated polysaccharide found in various species of marine red algae, has been demonstrated to exhibit diverse bioactivities, including anti-inflammatory effects. However, the protective effects of porphyran against cerebral ischemia and reperfusion (IR) injury have not been investigated. The aim of this study was to examine the neuroprotective effects of porphyran against brain IR injury and its underlying mechanisms using a gerbil model of transient forebrain ischemia (IR in the forebrain), which results in pyramidal cell (principal neuron) loss in the cornu ammonis 1 (CA1) subregion of the hippocampus on day 4 after IR. Porphyran (25 and 50 mg/kg) was orally administered daily for one week prior to IR. Pretreatment with 50 mg/kg of porphyran, but not 25 mg/kg, significantly attenuated locomotor hyperactivity and protected pyramidal cells located in the CA1 area from IR injury. The pretreatment with 50 mg/kg of porphyran significantly suppressed the IR-induced activation and proliferation of microglia in the CA1 subregion. Additionally, the pretreatment significantly inhibited the overexpressions of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing protein-3 (NLRP3) inflammasome complex, and pro-inflammatory cytokines (interleukin 1 beta and interleukin 18) induced by IR in the CA1 subregion. Overall, our findings suggest that porphyran exerts neuroprotective effects against brain IR injury, potentially by reducing the reaction (activation) and proliferation of microglia and reducing NLRP3 inflammasome-mediated neuroinflammation.

Fucoidan protects CA1 pyramidal neurons of the hippocampus and preserves the cognitive profile of rats subjected to transient forebrain ischemia

Fucoidan, a polysaccharide derived from brown seaweeds, especially Fucus Vesiculosus has been documented as an effective neuroprotectant. This study investigates the efficacy of fucoidan in mitigating the cognitive deficits in the rat model of vascular dementia induced through the 4-vessel occlusions (4VO) method. Male Wistar rats weighing about 250-300 g were randomly assigned into four groups, sham, lesion (4VO), 4VO + F5mg/kg, and 4VO + F50mg/kg. The rats were assessed for cognitive behaviour performance through novel object task, T-maze and Morris water maze, and finally, the hippocampus from the brain was harvested to quantify the profile of CA1 pyramidal neurons through CFV staining and the expression of inflammatory markers and angiogenic markers were quantified through western blot assessment on day7 and 30 of the study period. The rats were treated with fucoidan at a dose of 50 mg/kg. body weight showed improved spatial learning and memory compared to the lesion group and the cytoarchitecture of CA1 pyramidal cells was observed to be well preserved. The expression of IL1β, IL6, TNFα, NFk-B, CD68 and HIFα were found to be down-regulated, while on the contrary the VEGFR2 and angiopoietin-1 were up regulated in the 4VO + F50mg/kg group when compared with the lesion group. In conclusion, this study ascertains the role of fucoidan in support of the cognitive profile of rats subjected to vascular dementia and in preserving the CA1 pyramidal neurons of the hippocampus by regulating the inflammatory and angiogenic factors.

Marine-derived Compounds: A Powerful Platform for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a debilitating form of dementia that primarily affects cholinergic neurons in the brain, significantly reducing an individual's capacity for learning and creative skills and ultimately resulting in an inability to carry out even basic daily tasks. As the elderly population is exponentially increasing, the disease has become a significant concern for society. Therefore, neuroprotective substances have garnered considerable interest in addressing this universal issue. Studies have shown that oxidative damage to neurons contributes to the pathophysiological processes underlying AD progression. In AD, tau phosphorylation and glutamate excitotoxicity may play essential roles, but no permanent cure for AD is available. The existing therapies only manage the early symptoms of AD and often come with numerous side effects and toxicities. To address these challenges, researchers have turned to nature and explored various sources such as plants, animals, and marine organisms. Many historic holy books from different cultures emphasize that adding marine compounds to the regular diet enhances brain function and mitigates its decline. Consequently, researchers have devoted significant time to identifying potentially active neuroprotective substances from marine sources. Marine-derived compounds are gaining recognition due to their abundant supply of diverse chemical compounds with biological and pharmacological potential and unique mechanisms of action. Several studies have reported that plants exhibit multitarget potential in treating AD. In light of this, the current study focuses on marine-derived components with excellent potential for treating this neurodegenerative disease.

Antimetastatic effect of fucoidan against non-small cell lung cancer by suppressing non-receptor tyrosine kinase and extracellular signal-related kinase pathway

BACKGROUND/OBJECTIVES

Fucoidan, a polysaccharide content in brown algae, has been reported to inhibit the growth of cancer cells. The present study aimed to investigate the suppression effects of fucoidan on A549 non-small cell lung cancer cells migration.

MATERIALS/METHODS

The anti-migratory activity of fucoidan in A549 cells was examined by wound healing assay and phalloidin-rhodamine staining in response to fucoidan (0-100 µg/mL) treatment for 48 h. Western blot analysis was performed to clarify the protein expressions relevant to migratory activity.

RESULTS

Fucoidan (25-100 µg/mL) significantly suppressed A549 cells migration together with reduced the intensity of phalloidin-rhodamine which detect filopodia and lamellipodia protrusions at 48 h of treatment. The protein expression indicated that fucoidan significantly suppressed the phosphorylation of focal adhesion kinase (FAK), Src, and extracellular signal-related kinase (ERK). In addition, the phosphorylation of p38 in A549 cells was found to be increased.

CONCLUSIONS

Our data conclude that fucoidan exhibits anti-migratory activities against lung cancer A549 cells mediated by inhibiting ERK1/2 and FAK-Src pathway.

Fucoidan from Fucus vesiculosus prevents the loss of dopaminergic neurons by alleviating mitochondrial dysfunction through targeting ATP5F1a

Parkinson's disease is a neurodegenerative disease that is characterized by the loss of dopaminergic neurons. Fucoidan, which has emerged as a neuroprotective agent, is a marine-origin sulfated polysaccharide enriched in brown algae and sea cucumbers. However, variations in structural characteristics exist among fucoidans derived from different sources, resulting in a wide spectrum of biological effects. It is urgent to find the fucoidan with the strongest neuroprotective effect, and the mechanism needs to be further explored. We isolated and purified four different fucoidan species with different chemical structures and found that Type II fucoidan from Fucus vesiculosus (FvF) significantly improved mitochondrial dysfunction, prevented neuronal apoptosis, reduced dopaminergic neuron loss, and improved motor deficits in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. Further mechanistic investigation revealed that the ATP5F1a protein is a key target responsible for alleviating mitochondrial dysfunction of FvF to exert neuroprotective effects. This study highlights the favorable properties of FvF for neuroprotection, making FvF a promising candidate for the treatment of PD.

LAMP-2A ablation in hippocampal CA1 astrocytes confers cerebroprotection and ameliorates neuronal injury after global brain ischemia

Reactive astrogliosis and neuronal death are major features of brain tissue damage after transient global cerebral ischemia/reperfusion (I/R). The CA1 subfield in the hippocampus is particularly susceptible to cell death after I/R. Recently, attention has focused on the relationship between the autophagy-lysosomal pathway and cerebral ischemia. Lysosomal-associated membrane protein type-2A (LAMP-2A) is a key protein in chaperone-mediated autophagy (CMA). However, LAMP-2A expression in astrocytes of the hippocampus and its influence on brain injury following I/R remain unknown. Here, we show that LAMP-2A is elevated in astrocytes of the CA1 hippocampal subfield after I/R and in primary cultured astrocytes after transient oxygen-glucose deprivation (OGD). Conditional LAMP-2A knockdown in CA1 astrocytes inhibited astrocyte activation and prevented neuronal death by inhibiting the mitochondrial pathway of apoptosis after I/R, suggesting that elevated astrocytic LAMP-2A contributes to regional ischemic vulnerability. Furthermore, astrocytic LAMP-2A ablation ameliorated the spatial learning and memory deficits caused by I/R. Conditional astrocytic LAMP-2A knockdown also prevented the loss of hippocampal synapses and dendritic spines, improved the synaptic ultrastructure, and inhibited the reduced expression of synaptic proteins after ischemia. Thus, our findings demonstrate that astrocytic LAMP-2A expression increases upon I/R and that LAMP-2A ablation specifically in hippocampal astrocytes contributes to cerebroprotection, suggesting a novel neuroprotective strategy for patients with global ischemia.

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.

Polysaccharides from Laminaria japonica protect memory abilities and neurogenesis in mice after cranial irradiation through ameliorating neuroinflammation and collagen IV degradation

BACKGROUND

Radiation-induced brain injury (RIBI) is one of the most common long-term complications for patients with malignant brain tumors after radiotherapy. At present, there is no effective treatment for RIBI. Recent studies have also confirmed that polysaccharides from laminaria japonica (LJP) display potential neuroprotective function. However, its mechanisms of neuroprotection remain unclear.

AIM

In this study, we aimed to explore the effect and underlying mechanism of LJP on neurogenesis in radiation-induced brain injury mice.

METHODS

SPF two-month-old male mice were randomly divided into control group (Con), LJP treatment group (LJP), irradiation group (IR), and irradiation with LJP treatment group (IR + LJP). LJP (40 mg/kg/day) was intraperitoneally injected at one day before radiation for seven consecutive days (once daily). The mice were exposed to 10 Gy × 2 fractionated doses, once every other day, with a total dose of 20 Gy. Changes in cognitive function of mice following radiation were evaluated by the Morris water maze test. Furthermore, body weight and general status of mice were measured throughout the experiment. Immunohistochemical staining for neural proliferating cells (Ki67+ cells) and immature neurons (DCX + cells) was utilized to assay changes of neurogenesis in hippocampus. Microglial activation and collagen IV deposition within the neurogenic microenvironment were observed respectively by immunohistochemical staining for Iba-1 and Collagen IV in the hippocampus. Levels of pro-inflammatory cytokines (TNF-α and IL-1β) in the hippocampus were detected by ELISA kits post-radiation.

RESULTS

Morris water maze test showed that LJP therapy markedly reduced the escape latency and increased the times of crossing platform and percent time of the target quadrant in the radiated mice. In addition, the decrease of the neural proliferating cells (Ki67+ cells) and immature neurons (DCX + cells) in the hippocampus of mice following irradiation was significantly mitigated by the LJP treatment, suggesting that LJP could prevent from neurogenesis damage after irradiation. LJP injection significantly attenuated degradation of collagen IV, activation of microglia, and increase of pro-inflammatory cytokines (TNF-α and IL-1β) levels in the neurogenic microenvironment of the hippocampus after radiation.

CONCLUSION

These findings suggest that LJP early treatment may mitigate radiation-induced cognitive impairments and that its mechanism may relate to its protection of neurogenesis by alleviating neuroinflammation and collagen IV degradation within the neurogenic microenvironment.

Hypothermia Induced by Oxcarbazepine after Transient Forebrain Ischemia Exerts Therapeutic Neuroprotection through Transient Receptor Potential Vanilloid Type 1 and 4 in Gerbils

In the present study, we investigated the neuroprotective effect of post-ischemic treatment with oxcarbazepine (OXC; an anticonvulsant compound) against ischemic injury induced by transient forebrain ischemia and its mechanisms in gerbils. Transient ischemia was induced in the forebrain by occlusion of both common carotid arteries for 5 min under normothermic conditions (37 ± 0.2 °C). The ischemic gerbils were treated with vehicle, hypothermia (whole-body cooling; 33.0 ± 0.2 °C), or 200 mg/kg OXC. Post-ischemic treatments with vehicle and hypothermia failed to attenuate and improve, respectively, ischemia-induced hyperactivity and cognitive impairment (decline in spatial and short-term memory). However, post-ischemic treatment with OXC significantly attenuated the hyperactivity and the cognitive impairment, showing that OXC treatment significantly reduced body temperature (to about 33 °C). When the hippocampus was histopathologically examined, pyramidal cells (principal neurons) were dead (lost) in the subfield Cornu Ammonis 1 (CA1) of the gerbils treated with vehicle and hypothermia on Day 4 after ischemia, but these cells were saved in the gerbils treated with OXC. In the gerbils treated with OXC after ischemia, the expression of transient receptor potential vanilloid type 1 (TRPV1; one of the transient receptor potential cation channels) was significantly increased in the CA1 region compared with that in the gerbils treated with vehicle and hypothermia. In brief, our results showed that OXC-induced hypothermia after transient forebrain ischemia effectively protected against ischemia–reperfusion injury through an increase in TRPV1 expression in the gerbil hippocampal CA1 region, indicating that TRPV1 is involved in OXC-induced hypothermia.

Fucoidan-functionalized polysaccharide submicroparticles loaded with alteplase for efficient targeted thrombolytic therapy

Intravenous administration of fibrinolytic drugs is the standard treatment of acute thrombotic diseases. However, current fibrinolytics exhibit limited clinical efficacy because of their short plasma half-lives and might trigger hemorrhagic transformations. Therefore, it is mandatory to develop innovative nanomedicine-based solutions for more efficient and safer thrombolysis with biocompatible and biodegradable thrombus-targeted nanocarrier. Herein, fucoidan-functionalized hydrogel polysaccharide submicroparticles with high biocompatibility are elaborated by the inverse miniemulsion/crosslinking method. They are loaded with the gold standard fibrinolytic - alteplase - to direct site-specific fibrinolysis due to nanomolar interactions between fucoidan and P-selectin overexpressed on activated platelets and endothelial cells in the thrombus area. The thrombus targeting properties of these particles are validated in a microfluidic assay containing recombinant P-selectin and activated platelets under arterial and venous blood shear rates as well as in vivo. The experiments on the murine model of acute thromboembolic ischemic stroke support this product's therapeutic efficacy, revealing a faster recanalization rate in the middle cerebral artery than with free alteplase, which reduces post-ischemic cerebral infarct lesions and blood-brain barrier permeability. Altogether, this proof-of-concept study demonstrates the potential of a biomaterial-based targeted nanomedicine for the precise treatment of acute thrombotic events, such as ischemic stroke.

Neuroprotective and Anti-Inflammatory Effects of Pinus densiflora Bark Extract in Gerbil Hippocampus Following Transient Forebrain Ischemia

Korean red pine (Pinus densiflora) belongs to the Genus Pinus, and its bark contains a great amount of naturally occurring phenolic compounds. Until now, few studies have been conducted to assess the neuroprotective effects of Pinus densiflora bark extract against brain ischemic injury. The aim of this study was to investigate the neuroprotective effects of pre-treatment with the extract in the hippocampus following 5-min transient forebrain ischemia in gerbils. Furthermore, this study examined the anti-inflammatory effect as a neuroprotective mechanism of the extract. Pinus densiflora bark was extracted by pure water (100 °C), and this extract was quantitatively analyzed and contained abundant polyphenols, flavonoids, and proanthocyanidins. The extract (25, 50, and 100 mg/kg) was orally administered once a day for seven days before the ischemia. In the gerbil hippocampus, death of the pyramidal neurons was found in the subfield cornu ammonis 1 (CA1) five days after the ischemia. This death was significantly attenuated by pre-treatment with 100 mg/kg, not 25 or 50 mg/kg, of the extract. The treatment with 100 mg/kg of the extract markedly inhibited the activation of microglia (microgliosis) and significantly decreased the expression of pro-inflammatory cytokines (interleukin 1β and tumor necrosis factor α). In addition, the treatment significantly increased anti-inflammatory cytokines (interleukin 4 and interleukin 13). Taken together, this study clearly indicates that pre-treatment with 100 mg/kg of Pinus densiflora bark extract in gerbils can exert neuroprotection against brain ischemic injury by the attenuation of neuroinflammatory responses.

Differences in the prevention and control of cardiovascular and cerebrovascular diseases

At present, the prevention and control of cardiovascular diseases (CAVDs) has made initial advancements, although the prevention and control of cerebrovascular diseases (CEVDs) has not yet achieved the desired progress. In this paper, we review the prevention and control of CEVDs and CAVDs, and analyze the differences in prevention effects, and the pathological and physiological structures pertaining to CEVDs and CAVDs. Combined with the different effects of low-dose aspirin in the primary prevention of CEVDs and CAVDs by meta-analysis, aspirin plays a more important role in the primary prevention of CAVDs than CEVDs. We recognize the misunderstandings and blind spots concerning prevention and control of CEVDs, which can be summarized as follows: (1) CEVDs and CAVDs can be controlled by the same methods and drugs; (2) considering the same pathological factors for cardiovascular diseases; (3) a lack of understanding of the particularity of CEVDs; (4) a focus on platelets and neglect of cerebrovascular protection. In summary, our research clarifies the differences in the prevention measures and drugs used for CEVDs and CAVDs. Of particular concern is the serious lack of preventive drugs for CEVDs in clinical use. An ideal drug for the prevention of CEVDs should have protective effects on the blood, the vascular endothelium, the blood-brain barrier (BBB), and other related factors. Our review aims to highlight several issues in the current prevention of CEVDs and CAVDs, and to provide an optimized plan for preventive drug discovery.

Fucoidan: a promising agent for brain injury and neurodegenerative disease intervention

Brain injury and neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis are urgent medical problems, which severely threaten the life quality of patients and their carers. However, there are currently no effective therapies. Fucoidan is a natural compound found in brown algae and some animals, which has multiple biological and pharmacological activities, such as antioxidant, anti-tumor, anti-coagulant, anti-thrombotic, immunoregulatory, anti-viral, and anti-inflammatory effects. A growing number of studies have shown that fucoidan also exerts a neuroprotective function. Particularly, recent findings have indicated that fucoidan could slow down the neurodegenerative processes and show protective effects against brain injury, which might be of therapeutic value for intervening in brain injury and neurodegenerative diseases. In this review, we have discussed the pharmacokinetics of fucoidan as well as the molecular mechanisms by which fucoidan exerts its neuroprotective effect on some neurological disorders. Along with this, we have also summarized the potential benefits of fucoidan in combination with other drugs in the treatment of neurodegenerative diseases and brain injury. Although the extraction process of fucoidan has been improved well, more efforts should be devoted to the translational research and clinical trials of fucoidan in the near future.

Neuroprotective Effect for Cerebral Ischemia by Natural Products: A Review

Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. Stroke is a disease with high prevalence and incidence, the pathogenesis is a complex cascade reaction. In recent years, it’s reported that a vast number of natural products have demonstrated beneficial effects on stroke worldwide. Natural products have been discovered to modulate activities with multiple targets and signaling pathways to exert neuroprotection via direct or indirect effects on enzymes, such as kinases, regulatory receptors, and proteins. This review provides a comprehensive summary of the established pharmacological effects and multiple target mechanisms of natural products for cerebral ischemic injury in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications. In addition, the biological activity of natural products is closely related to their structure, and the structure-activity relationship of most natural products in neuroprotection is lacking, which should be further explored in future. Overall, we stress on natural products for their role in neuroprotection, and this wide band of pharmacological or biological activities has made them suitable candidates for the treatment of stroke.

Neuroprotective Effects of Salicin in a Gerbil Model of Transient Forebrain Ischemia by Attenuating Oxidative Stress and Activating PI3K/Akt/GSK3β Pathway

Salicin is a major natural compound of willow bark and displays diverse beneficial biological properties, such as antioxidant activity. However, little information available for the neuroprotective potential of salicin against ischemic brain injury has been reported. Thus, this study was performed to investigate the neuroprotective potential of salicin against ischemia and reperfusion (IR) injury and its mechanisms in the hippocampus using a gerbil model of 5-min transient ischemia (TI) in the forebrain, in which a massive loss (death) of pyramidal neurons cells occurred in the subfield Cornu Ammonis 1 (CA1) among the hippocampal subregions (CA1-3) at 5 days after TI. To examine neuroprotection by salicin, gerbils were pretreated with salicin alone or together with LY294002, which is a phosphatidylinositol 3-kinase (PI3K) inhibitor, once daily for 3 days before TI. Treatment with 20 mg/kg of salicin significantly protected CA1 pyramidal neurons against the ischemic injury. Treatment with 20 mg/kg of salicin significantly reduced the TI-induced increase in superoxide anion generation and lipid peroxidation in the CA1 pyramidal neurons after TI. The treatment also reinstated the TI-induced decrease in superoxide dismutases (SOD1 and SOD2), catalase, and glutathione peroxidase in the CA1 pyramidal cells after TI. Moreover, salicin treatment significantly elevated the levels of phosphorylation of Akt and glycogen synthase kinase-3β (GSK3β), which is a major downstream target of PI3K, in the ischemic CA1. Notably, the neuroprotective effect of salicin was abolished by LY294002. Taken together, these findings clearly indicate that salicin protects against ischemic brain injury by attenuating oxidative stress and activating the PI3K/Akt/GSK3β pathway.

Marine Natural Products: Promising Candidates in the Modulation of Gut-Brain Axis towards Neuroprotection

In recent decades, several neuroprotective agents have been provided in combating neuronal dysfunctions; however, no effective treatment has been found towards the complete eradication of neurodegenerative diseases. From the pathophysiological point of view, growing studies are indicating a bidirectional relationship between gut and brain termed gut-brain axis in the context of health/disease. Revealing the gut-brain axis has survived new hopes in the prevention, management, and treatment of neurodegenerative diseases. Accordingly, introducing novel alternative therapies in regulating the gut-brain axis seems to be an emerging concept to pave the road in fighting neurodegenerative diseases. Growing studies have developed marine-derived natural products as hopeful candidates in a simultaneous targeting of gut-brain dysregulated mediators towards neuroprotection. Of marine natural products, carotenoids (e.g., fucoxanthin, and astaxanthin), phytosterols (e.g., fucosterol), polysaccharides (e.g., fucoidan, chitosan, alginate, and laminarin), macrolactins (e.g., macrolactin A), diterpenes (e.g., lobocrasol, excavatolide B, and crassumol E) and sesquiterpenes (e.g., zonarol) have shown to be promising candidates in modulating gut-brain axis. The aforementioned marine natural products are potential regulators of inflammatory, apoptotic, and oxidative stress mediators towards a bidirectional regulation of the gut-brain axis. The present study aims at describing the gut-brain axis, the importance of gut microbiota in neurological diseases, as well as the modulatory role of marine natural products towards neuroprotection.

Anti-cerebral ischemia reperfusion injury of polysaccharides: A review of the mechanisms

Cerebral ischemia-reperfusion injury can lead to a series of serious brain diseases and cause death or different degrees of disability. Polysaccharide is a kind of biological macromolecule with multiple pharmacological activities and has been proven that it may be used for the treatment of cerebral I/R injury in the future. By sorting out all relevant research from 2000 to 2020, we selected 74 references and identified 22 kinds of polysaccharides. Almost all of these polysaccharides are extracted from traditional Chinese medicine. Research shows that these polysaccharides can improve cerebral ischemia-reperfusion injury through anti-oxidative stress, inhibiting the neuroinflammation, glutamate neurotoxicity and neuronal apoptosis, and exerting neurotrophic effect. The specific mechanisms include clearing ROS and RNS, inhibiting the expression of inflammatory factors, maintaining mitochondrial homeostasis and blocking caspase cascade, regulating NMDA receptor and promoting angiogenesis. We hoped this review is instructive for researchers to design, research and develop polysaccharides.

Experimental pretreatment with YES-10®, a plant extract rich in scutellarin and chlorogenic acid, protects hippocampal neurons from ischemia/reperfusion injury via antioxidant role

Erigeron annuus (L.) PERS. (EALP) and Clematis mandshurica RUPR. (CMR) have been used in traditional remedies due to their medicinal effects. Recently, we reported that pretreatment with 200 mg/kg of YES-10^® (a combination of extracts from leaves of EALP and CMR) displayed neuroprotective effects against brain ischemia and reperfusion injury. The present study analyzed the major ingredients of YES-10^® and investigated whether neuroprotection from YES-10^® was dependent upon antioxidant effects in the cornu ammonis 1 (CA1) field in the gerbil hippocampus, after transient forebrain ischemia for 5 min. YES-10^® was demonstrated to predominantly contain scutellarin and chlorogenic acid. Pretreatment with YES-10^® significantly increased protein levels and the immunoreactivity of copper/zinc-superoxide dismutase (SOD1) and manganese-superoxide dismutase (SOD2) was in the pyramidal neurons of the hippocampal CA1 field when these were examined prior to transient ischemia induction. The increased SODs in CA1 pyramidal neurons following YES-10^® treatment were maintained after ischemic injury. In this case, the CA1 pyramidal neurons were protected from ischemia-reperfusion injury. Oxidative stress was significantly attenuated in the CA1 pyramidal neurons, and this was determined by 4-hydroxy-2-nonenal immunohistochemistry and dihydroethidium histofluorescence staining. Taken together, the results indicated that YES-10^® significantly attenuated transient ischemia-induced oxidative stress and may be utilized for developing a protective agent against ischemic insults.

Physical Stress Induced Reduction of Proliferating Cells and Differentiated Neuroblasts Is Ameliorated by Fermented Laminaria japonica Extract Treatment

Laminaria japonica is widely cultivated in East Asia, including South Korea. Fucoidan, a main component of L. japonica, protects neurons from neurological disorders such as ischemia and traumatic brain injury. In the present study, we examined the effects of extract from fermented L. japonica on the reduction of proliferating cells and neuroblasts in mice that were physically (with electric food shock) or psychologically (with visual, auditory and olfactory sensation) stressed with the help of a communication box. Vehicle (distilled water) or fermented L. japonica extract (50 mg/kg) were orally administered to the mice once a day for 21 days. On the 19th day of the treatment, physical and psychological stress was induced by foot shock using a communication box and thereafter for three days. Plasma corticosterone levels were significantly increased after exposure to physical stress and decreased Ki67 positive proliferating cells and doublecortin immunoreactive neuroblasts. In addition, western blot analysis demonstrated that physical stress as well as psychological stress decreased the expression levels of brain-derived neurotrophic factor (BDNF) and the number of phosphorylated cAMP response element binding protein (pCREB) positive nuclei in the dentate gyrus. Fermentation of L. japonica extract significantly increased the contents of reduced sugar and phenolic compounds. Supplementation with fermented L. japonica extract significantly ameliorated the increases of plasma corticosterone revels and decline in the proliferating cells, neuroblasts, and expression of BDNF and pCREB in the physically stressed mice. These results indicate that fermented L. japonica extract has positive effects in ameliorating the physical stress induced reduction in neurogenesis by modulating BDNF and pCREB expression in the dentate gyrus.

Pycnogenol® Supplementation Attenuates Memory Deficits and Protects Hippocampal CA1 Pyramidal Neurons via Antioxidative Role in a Gerbil Model of Transient Forebrain Ischemia

Pycnogenol^® (an extract of the bark of French maritime pine tree) is used for dietary supplement and known to have excellent antioxidative efficacy. However, there are few reports on neuroprotective effect of Pycnogenol^® supplementation and its mechanisms against ischemic injury following transient forebrain ischemia (TFI) in gerbils. Now, we examined neuroprotective effect and its mechanisms of Pycnogenol^® in the gerbils with 5-min TFI, which evokes a significant death (loss) of pyramidal cells located in the cornu ammonis (CA1) region of gerbil hippocampus from 4-5 days post-TFI. Gerbils were pretreated with 30, 40, and 50 mg/kg of Pycnogenol^® once a day for 7 days before TFI surgery. Treatment with 50 mg/kg, not 30 or 40 mg/kg, of Pycnogenol^® potently protected learning and memory, as well as CA1 pyramidal cells, from ischemic injury. Treatment with 50 mg/kg Pycnogenol^® significantly enhanced immunoreactivity of antioxidant enzymes (superoxide dismutases and catalase) in the pyramidal cells before and after TFI induction. Furthermore, the treatment significantly reduced the generation of superoxide anion, ribonucleic acid oxidation and lipid peroxidation in the pyramidal cells. Moreover, interestingly, its neuroprotective effect was abolished by administration of sodium azide (a potent inhibitor of SODs and catalase activities). Taken together, current results clearly indicate that Pycnogenol^® supplementation can prevent neurons from ischemic stroke through its potent antioxidative role.

Experimental Pretreatment with Chlorogenic Acid Prevents Transient Ischemia-Induced Cognitive Decline and Neuronal Damage in the Hippocampus through Anti-Oxidative and Anti-Inflammatory Effects

Chlorogenic acid (CGA), an ester of caffeic acid and quinic acid, is among the phenolic acid compounds which can be naturally found in green coffee extract and tea. CGA has been studied since it displays significant pharmacological properties. The aim of this study was to investigate the effects of CGA on cognitive function and neuroprotection including its mechanisms in the hippocampus following transient forebrain ischemia in gerbils. Memory and learning following the ischemia was investigated by eight-arm radial maze and passive avoidance tests. Neuroprotection was examined by immunohistochemistry for neuronal nuclei-specific protein and Fluoro-Jade B histofluorescence staining. For mechanisms of the neuroprotection, alterations in copper, zinc-superoxide dismutase (SOD1), SOD2 as antioxidant enzymes, dihydroethidium and 4-hydroxy-2-nonenal as indicators for oxidative stress, and anti-inflammatory cytokines (interleukin (IL)-4 and IL-13) and pro-inflammatory cytokines (tumor necrosis factor α (TNF-α) and IL-2) were examined by Western blotting and/or immunohistochemistry. As a result, pretreatment with 30 mg/kg CGA attenuated cognitive impairment and displayed a neuroprotective effect against transient forebrain ischemia (TFI). In Western blotting, the expression levels of SOD2 and IL-4 were increased due to pretreatment with CGA and, furthermore, 4-HNE production and IL-4 expressions were inhibited by CGA pretreatment. Additionally, pretreated CGA enhanced antioxidant enzymes and anti-inflammatory cytokines and, in contrast, attenuated oxidative stress and pro-inflammatory cytokine expression. Based on these results, we suggest that CGA can be a useful neuroprotective material against ischemia-reperfusion injury due to its antioxidant and anti-inflammatory efficacies.

Brain Factor-7® improves learning and memory deficits and attenuates ischemic brain damage by reduction of ROS generation in stroke in vivo and in vitro

Brain Factor-7® (BF-7), silk fibroin peptide, is known to be effective in improvement of memory and learning ability. In this study, the effects of BF-7 (10 mg/kg, p.o., pre-treatment for 7 days and post-treatment for 7 days) on neuroprotection and memory and learning functions were investigated in a rat model of transient focal cerebral ischemia and a gerbil model of transient global forebrain ischemia. Furthermore, to find the mechanism of BF-7, we examined the neuroprotective and antioxidative effects of BF-7 in vitro using neuroblastoma (SH-SY5Y) cells. In vivo model, treatment with BF-7 significantly reduced the number of errors in 8-arm maze test and significantly increased latency time in passive avoidance test at 7 days after focal ischemia compared to those in the vehicle-treated group. In addition, treatment with BF-7 significantly decreased the infarct size or neuronal death at 7 day following transient ischemia compared to that in the vehicle-treated group. In vitro model, 10 or 20 μg/ml of BF-7 treatment significantly increased cell viability in dose-dependent manner. In addition, oxidative stress was significantly attenuated in the ischemic cells, showing that 10 or 20 μg/ml of BF-7 treatment significantly reduced the generation of reactive oxygen species (ROS) compared to that in the ischemic cells. These results indicate that BF-7 treatment can attenuate ischemic damages and improve memory deficits via reduction of ROS generation.

Neuroprotective Potentials of Marine Algae and Their Bioactive Metabolites: Pharmacological Insights and Therapeutic Advances

Beyond their significant contribution to the dietary and industrial supplies, marine algae are considered to be a potential source of some unique metabolites with diverse health benefits. The pharmacological properties, such as antioxidant, anti-inflammatory, cholesterol homeostasis, protein clearance and anti-amyloidogenic potentials of algal metabolites endorse their protective efficacy against oxidative stress, neuroinflammation, mitochondrial dysfunction, and impaired proteostasis which are known to be implicated in the pathophysiology of neurodegenerative disorders and the associated complications after cerebral ischemia and brain injuries. As was evident in various preclinical studies, algal compounds conferred neuroprotection against a wide range of neurotoxic stressors, such as oxygen/glucose deprivation, hydrogen peroxide, glutamate, amyloid β, or 1-methyl-4-phenylpyridinium (MPP+) and, therefore, hold therapeutic promise for brain disorders. While a significant number of algal compounds with promising neuroprotective capacity have been identified over the last decades, a few of them have had access to clinical trials. However, the recent approval of an algal oligosaccharide, sodium oligomannate, for the treatment of Alzheimer's disease enlightened the future of marine algae-based drug discovery. In this review, we briefly outline the pathophysiology of neurodegenerative diseases and brain injuries for identifying the targets of pharmacological intervention, and then review the literature on the neuroprotective potentials of algal compounds along with the underlying pharmacological mechanism, and present an appraisal on the recent therapeutic advances. We also propose a rational strategy to facilitate algal metabolites-based drug development.

Marine Biocompounds for Neuroprotection-A Review

While terrestrial organisms are the primary source of natural products, recent years have witnessed a considerable shift towards marine-sourced biocompounds. They have achieved a great scientific interest due to the plethora of compounds with structural and chemical properties generally not found in terrestrial products, exhibiting significant bioactivity ten times higher than terrestrial-sourced molecules. In addition to the antioxidant, anti-thrombotic, anti-coagulant, anti-inflammatory, anti-proliferative, anti-hypertensive, anti-diabetic, and cardio-protection properties, marine-sourced biocompounds have been investigated for their neuroprotective potential. Thus, this review aims to describe the recent findings regarding the neuroprotective effects of the significant marine-sourced biocompounds.

Potential Beneficial Actions of Fucoidan in Brain and Liver Injury, Disease, and Intoxication-Potential Implication of Sirtuins

Increased interest in natural antioxidants has brought to light the fucoidans (sulfated polysaccharides present in brown marine algae) as highly valued nutrients as well as effective and safe therapeutics against several diseases. Based on their satisfactory in vitro antioxidant potency, researchers have identified this molecule as an efficient remedy for neuropathological as well as metabolic disorders. Some of this therapeutic activity is accomplished by upregulation of cytoprotective molecular pathways capable of restoring the enzymatic antioxidant activity and normal mitochondrial functions. Sirtuin-3 has been discovered as a key player for achieving the neuroprotective role of fucoidan by managing these pathways, whose ultimate goal is retrieving the entirety of the antioxidant response and preventing apoptosis of neurons, thereby averting neurodegeneration and brain injuries. Another pathway whereby fucoidan exerts neuroprotective capabilities is by interactions with P-selectin on endothelial cells, thereby preventing macrophages from entering the brain proper. Furthermore, beneficial influences of fucoidan have been established in hepatocytes after xenobiotic induced liver injury by decreasing transaminase leakage and autophagy as well as obtaining optimal levels of intracellular fiber, which ultimately prevents fibrosis. The hepatoprotective role of this marine polysaccharide also includes a sirtuin, namely sirtuin-1 overexpression, which alleviates obesity and insulin resistance through suppression of hyperglycemia, reducing inflammation and stimulation of enzymatic antioxidant response. While fucoidan is very effective in animal models for brain injury and neuronal degeneration, in general, it is accepted that fucoidan shows somewhat limited potency in liver. Thus far, it has been used in large doses for treatment of acute liver injuries. Thus, it appears that further optimization of fucoidan derivatives may establish enhanced versatility for treatments of various disorders, in addition to brain injury and disease.

Laminarin Pretreatment Provides Neuroprotection against Forebrain Ischemia/Reperfusion Injury by Reducing Oxidative Stress and Neuroinflammation in Aged Gerbils

Laminarin is a polysaccharide isolated from brown algae that has various biological and pharmacological activities, such as antioxidant and anti-inflammatory properties. We recently reported that pretreated laminarin exerted neuroprotection against transient forebrain ischemia/reperfusion (IR) injury when we pretreated with 50 mg/kg of laminarin once a day for seven days in adult gerbils. However, there have been no studies regarding a neuroprotective effect of pretreated laminarin against IR injury in aged animals and its related mechanisms. Therefore, in this study, we intraperitoneally inject laminarin (50 mg/kg) once a day to aged gerbils for seven days before IR (5-min transient ischemia) surgery and examine the neuroprotective effect of laminarin treatment and the mechanisms in the gerbil hippocampus. IR injury in vehicle-treated gerbils causes loss (death) of pyramidal neurons in the hippocampal CA1 field at five days post-IR. Pretreatment with laminarin effectively protects the CA1 pyramidal neurons from IR injury. Regarding the laminarin-treated gerbils, production of superoxide anions, 4-hydroxy-2-nonenal expression and pro-inflammatory cytokines [interleukin(IL)-1β and tumor necrosis factor-α] expressions are significantly decreased in the CA1 pyramidal neurons after IR. Additionally, laminarin treatment significantly increases expressions of superoxide dismutase and anti-inflammatory cytokines (IL-4 and IL-13) in the CA1 pyramidal neurons before and after IR. Taken together, these findings indicate that laminarin can protect neurons from ischemic brain injury in an aged population by attenuating IR-induced oxidative stress and neuroinflammation.

Protective potential effects of fucoidan in hepatic cold ischemia-rerfusion injury in rats

The necessity to increase the efficiency of organ preservation has pushed physicians to consider the use of pharmacological additives in preservation solutions to minimize ischemia reperfusion injury. Here, we evaluated the effect of fucoidan, sulfated polysaccharide from brown seaweed, as an additive to IGL-1 (Institut Georges Lopez) preservation solution. Livers from Wistar rats were preserved for 24 h at 4 °C in IGL-1 solution, enriched or not with fucoidan (100 mg/L). Thereafter, they were subjected to reperfusion (2 h, at 37 °C) using an isolated perfused rat liver model. The addition of fucoidan to IGL-1 solution reduced hepatic injury (AST, ALT) and improved liver function compared to IGL-1 solution without fucoidan. In addition, we noted a significant increase in the phosphorylation of AMPK, AKT protein kinase and GSK3-β, leading to a reduction in VDAC phosphorylation, as well as a reduction in apoptosis (caspase 3), mitochondrial damage, oxidative stress and endoplasmic reticulum (ER) stress markers. Furthermore, ERK1/2 and P38 MAPKs phosphorylation significantly decreased after supplementation of IGL-1 solution with fucoidan. In conclusion, the supplementation of IGL-1 solution with fucoidan maintained liver graft integrity and function through the prevention of the ER stress, oxidative stress and mitochondrial dysfunction. Fucoidan could be considered as potential natural therapeutic agent to alleviate graft injury.

Evaluation of the effects of pycnogenol (French maritime pine bark extract) supplementation on inflammatory biomarkers and nutritional and clinical status in traumatic brain injury patients in an intensive care unit: A randomized clinical trial protocol

Background

Traumatic brain injury (TBI) is one of the major health and socioeconomic problems in the world. Immune-enhancing enteral formula has been proven to significantly reduce infection rate in TBI patients. One of the ingredients that can be used in immunonutrition formulas to reduce inflammation and oxidative stress is pycnogenol.

Objective

The objective of this work is to survey the effect of pycnogenol on the clinical, nutritional, and inflammatory status of TBI patients.

Methods

This is a double-blind, randomized controlled trial. Block randomization will be used. An intervention group will receive pycnogenol supplementation of 150 mg for 10 days and a control group will receive a placebo for the same duration. Inflammatory status (IL-6, IL- 1β, C-reactive protein) and oxidative stress status (malondialdehyde, total antioxidant capacity), at the baseline, at the 5th day, and at the end of the study (10th day) will be measured. Clinical and nutritional status will be assessed three times during the intervention. The Sequential Organ Failure Assessment (SOFA) questionnaire for assessment of organ failure will be filled out every other day. The mortality rate will be calculated within 28 days of the start of the intervention. Weight, body mass index, and body composition will be measured. All analyses will be conducted by an initially assigned study arm in an intention-to-treat analysis.

Discussion

We expect that supplementation of 150 mg pycnogenol for 10 days will improve clinical and nutritional status and reduce the inflammation and oxidative stress of the TBI patients.

Trial registration

This trial is registered at clinicaltrials.gov (ref: NCT03777683) at 12/13/2018.

YES-10, A Combination of Extracts from Clematis mandshurica RUPR. and Erigeron annuus (L.) PERS., Prevents Ischemic Brain Injury in A Gerbil Model of Transient Forebrain Ischemia

: Clematis mandshurica RUPR. (CMR) and Erigeron annuus (L.) PERS. (EALP) have pharmacological effects including anti-inflammatory activity and been used in traditional medicines in Asia. However, neuroprotective effects of CMR and/or EALP extracts against brain ischemic insults have never been addressed. Thus, the aim of this study was to examine neuroprotective effects of YES-10, a combination of extracts from CMR and EALP (combination ratio, 1:1), in the hippocampus following ischemia/reperfusion in gerbils. Protection of neurons was investigated by cresyl violet staining, fluoro-jade B histofluorescence staining and immunohistochemistry for neuronal nuclei. In addition, attenuation of gliosis was studied by immunohistochemistry for astrocytic and microglial markers. Treatments with 50 or 100 mg/kg YES-10 failed to protect neurons in the hippocampus after ischemia/reperfusion injury. However, administration of 200 mg/kg YES-10 protected neurons from ischemia/reperfusion injury and attenuated reactive gliosis. These findings strongly suggest that a combination of extracts from CMR and EALP can be used as a prevention approach/drug against brain ischemic damage.

Post-treatment with oxcarbazepine confers potent neuroprotection against transient global cerebral ischemic injury by activating Nrf2 defense pathway

Oxcarbazepine (OXC), a voltage-gated sodium channel blocker, is an antiepileptic medication and used for the bipolar disorders treatment. Some voltage-gated sodium channel blockers have been demonstrated to display strong neuroprotective properties in models of cerebral ischemia. However, neuroprotective effects and mechanisms of OXC have not yet been reported. Here, we investigated the protective effect of OXC and its mechanisms in the cornu ammonis 1 subfield (CA1) of gerbils subjected to 5 min of transient global cerebral ischemia (tGCI). tGCI led to death of most pyramidal neurons in CA1 at 5 days after ischemia. OXC (100 and 200 mg/kg) was intraperitoneally administered once at 30 min after tGCI. Treatment with 200 mg/kg, not 100 mg/kg OXC, significantly protected CA1 pyramidal neurons from tGCI-induced injury. OXC treatment significantly decreased superoxide anion production, 4-hydroxy-2-nonenal and 8-hydroxyguanine levels in ischemic CA1 pyramidal neurons. In addition, the treatment restored levels of superoxide dismutases, catalase, and glutathione peroxidase. Furthermore, the treatment distinctly inhibited tGCI-induced microglia activation and significantly reduced levels of pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-α). In particular, OXC treatment significantly enhanced expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream protein heme oxygenase-1 in ischemic CA1. The neuroprotective effects of OXC were abolished by brusatol (an inhibitor of Nrf2). Taken together, these results indicate that post-treatment of OXC can display neuroprotection against brain injuries following ischemic insults. This neuroprotection may be displayed by attenuation of oxidative stress and neuroinflammation, which can be mediated by activation of Nrf2 pathway.

Pre-Treatment with Laminarin Protects Hippocampal CA1 Pyramidal Neurons and Attenuates Reactive Gliosis Following Transient Forebrain Ischemia in Gerbils

Transient brain ischemia triggers selective neuronal death/loss, especially in vulnerable regions of the brain including the hippocampus. Laminarin, a polysaccharide originating from brown seaweed, has various pharmaceutical properties including an antioxidant function. To the best of our knowledge, few studies have been conducted on the protective effects of laminarin against ischemic injury induced by ischemic insults. In this study, we histopathologically investigated the neuroprotective effects of laminarin in the Cornu Ammonis 1 (CA1) field of the hippocampus, which is very vulnerable to ischemia-reperfusion injury, following transient forebrain ischemia (TFI) for five minutes in gerbils. The neuroprotective effect was examined by cresyl violet staining, Fluoro-Jade B histofluorescence staining and immunohistochemistry for neuronal-specific nuclear protein. Additionally, to study gliosis (glial changes), we performed immunohistochemistry for glial fibrillary acidic protein to examine astrocytes, and ionized calcium-binding adaptor molecule 1 to examine microglia. Furthermore, we examined alterations in pro-inflammatory M1 microglia by using double immunofluorescence. Pretreatment with 10 mg/kg laminarin failed to protect neurons in the hippocampal CA1 field and did not attenuate reactive gliosis in the field following TFI. In contrast, pretreatment with 50 or 100 mg/kg laminarin protected neurons, attenuated reactive gliosis and reduced pro-inflammatory M1 microglia in the CA1 field following TFI. Based on these results, we firmly propose that 50 mg/kg laminarin can be strategically applied to develop a preventative against injuries following cerebral ischemic insults.

Therapeutic Hypothermia Improves Hind Limb Motor Outcome and Attenuates Oxidative Stress and Neuronal Damage in the Lumbar Spinal Cord Following Cardiac Arrest

Hypothermia enhances outcomes of patients after resuscitation after cardiac arrest (CA). However, the underlying mechanism is not fully understood. In this study, we investigated effects of hypothermic therapy on neuronal damage/death, microglial activation, and changes of endogenous antioxidants in the anterior horn in the lumbar spinal cord in a rat model of asphyxial CA (ACA). A total of 77 adult male Sprague–Dawley rats were randomized into five groups: normal, sham ACA plus (+) normothermia, ACA + normothermia, sham ACA + hypothermia, and ACA + hypothermia. ACA was induced for 5 min by injecting vecuronium bromide. Therapeutic hypothermia was applied after return of spontaneous circulation (ROSC) via rapid cooling with isopropyl alcohol wipes, which was maintained at 33 ± 0.5 °C for 4 h. Normothermia groups were maintained at 37 ± 0.2 °C for 4 h. Neuronal protection, microgliosis, oxidative stress, and changes of endogenous antioxidants were evaluated at 12 h, 1 day, and 2 days after ROSC following ACA. ACA resulted in neuronal damage from 12 h after ROSC and evoked obvious degeneration/loss of spinal neurons in the ventral horn at 1 day after ACA, showing motor deficit of the hind limb. In addition, ACA resulted in a gradual increase in microgliosis with time after ACA. Therapeutic hypothermia significantly reduced neuronal loss and attenuated hind limb dysfunction, showing that hypothermia significantly attenuated microgliosis. Furthermore, hypothermia significantly suppressed ACA-induced increases of superoxide anion production and 8-hydroxyguanine expression, and significantly increased superoxide dismutase 1 (SOD1), SOD2, catalase, and glutathione peroxidase. Taken together, hypothermic therapy was found to have a substantial impact on changes in ACA-induced microglia activation, oxidative stress factors, and antioxidant enzymes in the ventral horn of the lumbar spinal cord, which closely correlate with neuronal protection and neurological performance after ACA.

Altered Nurr1 protein expression in the hippocampal CA1 region following transient global cerebral ischemia

Nuclear receptor related 1 protein (Nurr1), a member of the nuclear receptor 4 family of orphan nuclear receptors, has been reported to display anti‑inflammatory properties. The present study investigated the alteration of Nurr1 immunoreactivity in the gerbil hippocampus proper following 5 min of transient global cerebral ischemia. In sham operated gerbils, Nurr1 immunoreactivity was observed in pyramidal neurons in all cornu ammonis 1‑3 (CA1‑3) subfields of the hippocampus proper. In ischemia‑operated gerbils, Nurr1 immunoreactivity was altered in the CA1 subfield. Nurr1 immunoreactivity in CA1 pyramidal neurons gradually decreased until 2 days post‑ischemia, and, at 4 days post‑ischemia, Nurr1 immunoreactivity was concentrated in CA1 pyramidal neurons. Additionally, Nurr1 immunoreactivity was newly expressed in microglia in the CA1 subfield at 4 days post‑ischemia. Conversely, in the CA2/3 subfield, time‑dependent alteration of Nurr1 immunoreactivity was not identified at any time following ischemia. These results indicated that the alteration of Nurr1 expression in the CA1 subfield in the hippocampus may be associated with the death of CA1 pyramidal neurons.

Transduced Tat-aldose Reductase Protects Hippocampal Neuronal Cells against Oxidative Stress-induced Damage

Aldose reductase (AR) protein, a member of the NADPH-dependent aldo-keto reductase family, reduces a wide range of aldehydes and enhances cell survival by inhibition of oxidative stress. Oxidative stress is known as one of the major pathological factor in ischemia. Since the precise function of AR protein in ischemic injury is fully unclear, we examined the function of AR protein in hippocampal neuronal (HT-22) cells and in an animal model of ischemia in this study. Cell permeable Tat-AR protein was produced by fusion of protein transduction domain in Tat for delivery into the cells. Tat-AR protein transduced into HT-22 cells and significantly inhibited cell death and regulated the mitogen-activate protein kinases (MAPKs), Bcl-2, Bax, and Caspase-3 under oxidative stress condition. In an ischemic animal model, Tat-AR protein transduced into the brain tissues through the blood-brain barrier (BBB) and drastically decreased neuronal cell death in hippocampal CA1 region. These results indicate that transduced Tat-AR protein has protective effects against oxidative stress-induced neuronal cell death in vitro and in vivo, suggesting that Tat-AR protein could be used as potential therapeutic agent in ischemic injury.

Therapies from Fucoidan: New Developments

Since our last review in 2015, the study and use of fucoidan has extended in several research areas. Clinical use of fucoidan for the treatment of renal disease has become available and human safety studies have been undertaken on radiolabeled fucoidan for the purpose of imaging thrombi. Fucoidan has been incorporated into an increasing number of commercially available supplements and topical treatments. In addition, new measuring techniques are now available to assess the biologically relevant uptake of fucoidans and to assist in production. Microbiome modulation and anti-pathogenic effects are increasingly promising applications for fucoidans, due to the need for alternative approaches to antibiotic use in the food chain. This review outlines promising new developments in fucoidan research, including potential future therapeutic use.

Efficacy of a low-dose melatonin pretreatment in protecting against the neurobehavioral consequences of chronic hypoperfusion in middle-aged female rats

Mild cognitive impairment (MCI) is characterized by a reduction in cerebral blood flow. Permanent ligation of the common carotid arteries (2VO) in the rat mimics the chronic decrease in CBF that characterizes aMCI. The current study determined if melatonin (a pineal hormone with neuroprotective properties) can attenuate the neurobehavioral consequences of 2VO using middle-aged female rats. Two weeks following 2VO or sham surgery, rats were tested on various learning and memory tasks. 2VO resulted in hyperlocomotion on the open field. Melatonin attenuated this 2VO-induced hyperactivity. 2VO impaired visual memory however this was not attenuated by melatonin administration. Neither 2VO nor melatonin affected spatial memory performance on the MWM or spatial recognition task. Y-maze testing revealed 2VO rats exhibited a lower spontaneous alternation pattern and performed a greater number of alternate arm returns compared to 2VO rats treated with melatonin. 2VO resulted in a significant loss of CA1 hippocampal neurons which was attenuated with melatonin treatment. Chronic melatonin was found to attenuate the neuronal consequences of chronic cerebral hypoperfusion but only conferred partial behavioral protection in middle-aged female rats. Our results demonstrate that inclusion of older rodents is important in neuroprotection studies as neuroprotective agents may act differently in an aged brain.

Effects of Crude Fucus distichus Subspecies evanescens Fucoidan Extract on Retinal Pigment Epithelium Cells-Implications for Use in Age-Related Macular Degeneration

Fucoidan extracts may have beneficial effects in age-related macular degeneration(AMD). Over-the-counter fucoidan preparations are generally undefined, crude extracts. In thisstudy, we investigated the effect of a crude fucoidan extract from Fucus distichus subspeciesevanescens (Fe) on the retinal pigment epithelium (RPE). Fe extract was investigated for chemicalcomposition and molar mass. It was tested in primary RPE and RPE cell line ARPE19. Oxidativestress was induced with tert-butyl hydroperoxide, cell viability evaluated with MTT assay, VEGFsecretion assessed in ELISA. Phagocytosis was evaluated in a fluorescence microscopic assay.Wound healing ability was tested in a scratch assay. Additionally, the inhibition of elastase andcomplement system by Fe extract was studied. The Fe extract contained about 61.9% fucose andhigh amounts of uronic acids (26.2%). The sulfate content was not as high as expected (6.9%). It wasnot toxic and not protective against oxidative stress. However, Fe extract was able to reduce VEGFsecretion in ARPE19. Phagocytosis was also reduced. Concerning wound healing, a delay could beobserved in higher concentrations. While some beneficial effects could be found, it seems tointerfere with RPE function, which may reduce its beneficial effects in AMD treatment.

Effects of Fucoidans from Five Different Brown Algae on Oxidative Stress and VEGF Interference in Ocular Cells

BACKGROUND

Fucoidans are interesting for potential usage in ophthalmology, and especially age-related macular degeneration. However, fucoidans from different species may vary in their effects. Here, we compare fucoidans from five algal species in terms of oxidative stress protection and vascular endothelial growth factor (VEGF) interference in ocular cells.

METHODS

Brown algae (Fucus vesiculosus, Fucus distichus subsp. evanescens, Fucus serratus, Laminaria digitata, Saccharina latissima) were harvested and fucoidans isolated by hot-water extraction. Fucoidans were tested in several concentrations (1, 10, 50, and 100 µg/mL). Effects were measured on a uveal melanoma cell line (OMM-1) (oxidative stress), retinal pigment epithelium (RPE) cell line ARPE19 (oxidative stress and VEGF), and primary RPE cells (VEGF). Oxidative stress was induced by H2O2 or tert-Butyl hydroperoxide (TBHP). Cell viability was investigated with methyl thiazolyl tetrazolium (MTT or MTS) assay, and VEGF secretion with ELISA. Affinity to VEGF was determined by a competitive binding assay.

RESULTS

All fucoidans protected OMM-1 from oxidative stress. However, in ARPE19, only fucoidan from Saccharina latissima was protective. The affinity to VEGF of all fucoidans was stronger than that of heparin, and all reduced VEGF secretion in ARPE19. In primary RPE, only the fucoidan from Saccharina latissima was effective.

CONCLUSION

Among the fucoidans from five different species, Saccharina latissima displayed the most promising results concerning oxidative stress protection and reduction of VEGF secretion.

Antioxidant Properties of Fucoidan Alleviate Acceleration and Exacerbation of Hippocampal Neuronal Death Following Transient Global Cerebral Ischemia in High-Fat Diet-Induced Obese Gerbils

Fucoidan, a natural sulfated polysaccharide, displays various biological activities including antioxidant properties. We examined the neuroprotective effect of fucoidan against transient global cerebral ischemia (tGCI) in high-fat diet (HFD)-induced obese gerbils and its related mechanisms. Gerbils received HFD for 12 weeks and fucoidan (50 mg/kg) daily for the last 5 days during HFD exposure, and they were subjected to 5-min tGCI. Pyramidal cell death was observed only in the CA 1 area (CA1) of the hippocampus in non-obese gerbils 5 days after tGCI. However, in obese gerbils, pyramidal cell death in the CA1 and CA2/3 occurred at 2 days and 5 days, respectively, after tGCI. In the obese gerbils, oxidative stress indicators (dihydroethidium, 8-hydroxyguanine and 4-hydroxy-2-nonenal) were significantly enhanced and antioxidant enzymes (SOD1 and SOD2) were significantly reduced in pre- and post-ischemic phases compared to the non-obese gerbils. Fucoidan treatment attenuated acceleration and exacerbation of tGCI-induced neuronal death in the CA1–3, showing that oxidative stress was significantly reduced, and antioxidant enzymes were significantly increased in pre- and post-ischemic phases. These findings indicate that pretreated fucoidan can relieve the acceleration and exacerbation of ischemic brain injury in an obese state via the attenuation of obesity-induced severe oxidative damage.