Astaxanthin reduces ischemic brain injury in adult rats

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.

Independent and combined effects of astaxanthin and omega-3 on behavioral deficits and molecular changes in a prenatal valproic acid model of autism in rats

Objectives: Autism is a devastating neurodevelopmental disorder and recent studies showed that omega-3 or astaxanthin might reduce autistic symptoms due to their anti-inflammatory properties. Therefore, we investigated the effects of omega-3 and astaxanthin on the VPA-induced autism model of rats.Material and Methods: Female Wistar albino pups (n = 40) were grouped as control, autistic, astaxanthin (2 mg/kg), omega-3 (200 mg/kg), and astaxanthin (2 mg/kg)+omega-3 (200 mg/kg). All groups except the control were prenatally exposed to VPA. Astaxanthin and omega-3 were orally administered from the postnatal day 41 to 68 and behavioral tests were performed between day 69 and 73. The rats were decapitated 24 h after the behavioral tests and hippocampal and prefrontal cytokines and 5-HT levels were analyzed by ELISA.Results: VPA rats have increased grooming behavior while decreased sociability (SI), social preference index (SPI), discrimination index (DI), and prepulse inhibition (PPI) compared to control. Additionally, IL-1β, IL-6, TNF-α, and IFN-γ levels increased while IL-10 and 5-HT levels decreased in both brain regions. Astaxanthin treatment raised SI, SPI, DI, PPI, and prefrontal IL-10 levels. It also raised 5-HT levels and decreased IL-6 levels in both brain regions. Omega-3 and astaxanthin + omega-3 increased the SI, SPI, DI, and PPI and decreased grooming behavior. Moreover, they increased IL-10 and 5-HT levels whereas decreased IL-1β, IL-6, TNF-α, IFN-γ levels in both brain regions.Conclusions: Our results showed that VPA administration mimicked the behavioral and molecular changes of autism in rats. Single and combined administration of astaxanthin and omega-3 improved the autistic-like behavioral and molecular changes in the VPA model of rats.

Chronic Stress as a Risk Factor for Type 2 Diabetes: Endocrine, Metabolic, and Immune Implications

BACKGROUND

Chronic stress is a condition of pressure on the brain and whole body, which in the long term may lead to a frank disease status, even including type 2 diabetes (T2D). Stress activates the hypothalamus-pituitary-adrenal axis with release of glucocorticoids (GCs) and catecholamines, as well as activation of the inflammatory pathway of the immune system, which alters glucose and lipid metabolism, ultimately leading to beta-cell destruction, insulin resistance and T2D onset. Alteration of the glucose and lipid metabolism accounts for insulin resistance and T2D outcome. Furthermore, stress-related subversion of the intestinal microbiota leads to an imbalance of the gut-brain-immune axis, as evidenced by the stress-related depression often associated with T2D. A condition of generalized inflammation and subversion of the intestinal microbiota represents another facet of stress-induced disease. In fact, chronic stress acts on the gut-brain axis with multiorgan consequences, as evidenced by the association between depression and T2D. Oxidative stress with the production of reactive oxygen species and cytokine-mediated inflammation represents the main hallmarks of chronic stress. ROS production and pro-inflammatory cytokines represent the main hallmarks of stress-related disorders, and therefore, the use of natural antioxidant and anti-inflammatory substances (nutraceuticals) may offer an alternative therapeutic approach to combat stress-related T2D. Single or combined administration of nutraceuticals would be very beneficial in targeting the neuro-endocrine-immune axis, thus, regulating major pathways involved in T2D onset. However, more clinical trials are needed to establish the effectiveness of nutraceutical treatment, dosage, time of administration and the most favorable combinations of compounds. Therefore, in view of their antioxidant and anti-inflammatory properties, the use of natural products or nutraceuticals for the treatment of stress-related diseases, even including T2D, will be discussed. Several evidences suggest that chronic stress represents one of the main factors responsible for the outcome of T2D.

The Effect of Antioxidant Astaxanthin on Intestinal Ischemia Reperfusion Damage in Rats

BACKGROUND

Mesenteric ischemia is a frequently encountered disease in surgical clinics, difficult to diagnose, and very mortal if not treated. Our study investigated the effects of astaxanthin, which is known to have potent antioxidant properties and is also known to have anti-inflammatory effects on ischemia-reperfusion (I/R) injury.

METHODS

A total of 32 healthy Wistar albino female rats were used in our study. Subjects were randomized and equally divided into 4 groups; control (laparotomy group only), I/R (transient mesenteric ischemia group only), astaxanthin 1 mg/kg and 10 mg/kg doses. The transient ischemia time was 60 minutes and the reperfusion time was 120 minutes. Tissue samples were taken from intracardiac blood and terminal ileum after reperfusion. Superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) from blood samples, interleukin-1 (IL-1), IL-6, tumor necrosis factor-α (TNFα), Caspase-3, P53 tests from terminal ileum were studied. Tissue samples were also taken for histopathological evaluation.

RESULTS

At the end of the study, both doses of astaxanthin were found to significantly reduce MDA level, CAT, and SOD enzymatic activity, whereas higher doses of astaxanthin significantly reduced MDA level, CAT, and SOD enzyme activities. In addition, cytokines such as TNFα, IL-1 and IL-6 were found to be reduced at both doses of astaxanthin, but only significantly inhibited at higher doses. We observed that inhibition of apoptosis reduced caspase-3 activity and P53 and deoxyribonucleic acid (DNA) fragmentation.

CONCLUSION

Astaxanthin, a potent antioxidant, and anti-inflammatory, significantly reduces ischemia and reperfusion injury, especially when used at a dose of 10 mg/kg. These data need to be confirmed by larger animal series and clinical studies.

Biological interactions and attenuation of MPTP-induced toxicity in Drosophila melanogaster by Trans-astaxanthin

Trans-astaxanthin (TA) is a carotenoid with amphipathic chemical structure found in yeast, and aquatic organisms. It is known to possess both antioxidative and anti-inflammatory properties. This study was carried out to investigate the ameliorative action of TA on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced toxicity in Drosophila melanogaster (Fruit fly). The flies were orally treated with TA (2.5 mg/10 g diet) and/or MPTP (500 µM) for 5 days. Thereafter, we evaluated selected biomarkers of locomotor deficits (acetylcholinesterase (AChE) and negative geotaxis), oxidative stress (hydrogen peroxide (H2O2), protein carbonyls (PC)), antioxidants (total thiols (T-SH), non-protein thiols, glutathione-S-transferase (GST) and catalase), and inflammation (nitric oxide (nitrite/nitrate) in the flies. Furthermore, we investigated molecular docking analysis of TA against Kelch-like ECH-associated protein 1 (Keap1)) of Homo sapiens and D. melanogaster. The results indicated that TA increased MPTP-induced decreased activities of AChE, GST, and catalase, as well as levels of non-protein thiols and T-SH compared with MPTP-treated flies (p < 0.05). Furthermore, TA attenuated inflammation, and improved locomotor deficit in the flies. The molecular docking data showed that TA had docking scores for binding both the Human and Drosophila Keap1, nearly closer to or higher than the standard inhibitor. The attenuating effects of TA against MPTP-induced toxicity could arise from its antioxidative and anti-inflammatory properties as well as its chemical structure.

Enhancing the neuroprotective effect of squid outer skin astaxanthin against rotenone-induced neurotoxicity in in-vitro model for Parkinson's disease

Rotenone is a widely used organic pesticide that induces neurotoxicity via inhibition of mitochondrial complex I and oxidative stress actions for the most of dopaminergic neurons as that occurring in Parkinsonism disease (PD). Astaxanthin (ASX) is a natural pigment (carotenoids) and a potent therapeutic compound due to its antioxidant and anti-inflammatory properties. The commercially important cephalopod Doryteuthis singhalensis is widely distributed in tropical and subtropical waters in World Ocean. D. singhalensis is an important source of astaxanthin that contains valuable biological active compounds with many valuable pharmacological effects. The present study evaluated the effect of astaxanthin in preventing rotenone-induced toxicity of SK-N-SH human neuroblastoma cells in an in vitro model of experimental Parkinsonism. The results revealed the strongly significant antioxidant capability of extracted squid astaxanthin in 1,1- diphenyl- 2- picrylhydrazyl (DPPH) radical scavenging activity. In addition, astaxanthin treatment based on dose dependent manner significantly attenuated rotenone induced cytotoxicity, mitochondrial dysfunction and oxidative stress in SKN- SH cells. It is concluded that the marine squid derived astaxanthin could be used as a potential neuroprotector against rotenone induced toxicity due to its antioxidant, and anti-apoptotic properties. Consequently, it could be a supportive remedy for neurodegenerative diseases like Parkinson's disease.

Protective Effect of Beta-Carotene against Myeloperoxidase- Mediated Oxidative Stress and Inflammation in Rat Ischemic Brain Injury

Oxidative stress and inflammatory reaction play critical roles in ischemia/reperfusion (I/R) injury in the brain. β-carotene (βCAR) is a naturally occurring pigment present in fruits and vegetables that expresses antioxidant and anti-inflammatory activities. This study was conducted to investigate the involvement of Bcl2/Bax and NF-κB signaling pathways in the potential protective role of βCAR against brain injury in a middle cerebral artery occlusion (MCAO) rat model. A focal brain ischemia model was created for 2 h, followed by reperfusion. Rats were given 10 and 20 mg/kg of βCAR for 7 days orally before induction of ischemia, at the start of reperfusion, and 3 days after ischemia. Scores of neurological deficit were rated 24 h after induction of ischemia. Motor coordination and spontaneous coordinate activities were assessed using rotarod and activity cage, respectively. After 2 h of the last dose, the animals were killed and their brains were extracted for further examinations. The results of the study show that βCAR diminished the score of neurological deficits and ameliorated motor coordination, balance, and locomotor activity in the I/R control group. Further, βCAR resulted in diminution of malondialdehyde (MDA) and augmentation of reduced glutathione (GSH) contents, as well as the elevation of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) enzyme activities in the brain homogenates of I/R rats. βCAR treatment significantly reduced nuclear factor kappa B (NF-κB) brain content and myeloperoxidase (MPO) activity and ameliorated the histological alterations in the brain tissues. βCAR significantly suppressed Bcl-2-associated X protein (Bax) and caspase-3 expression, as well as upregulated B-cell lymphoma-2 (Bcl-2) expression, suggesting a neuroprotective potential via downregulating NF-kB and protecting the rat brain against the I/R-associated apoptotic injury.

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.

Health benefits of astaxanthin against age-related diseases of multiple organs: A comprehensive review

Age-related diseases are associated with increased morbidity in the past few decades and the cost associated with the treatment of these age-related diseases exerts a substantial impact on social and health care expenditure. Anti-aging strategies aim to mitigate, delay and reverse aging-associated diseases, thereby improving quality of life and reducing the burden of age-related pathologies. The natural dietary antioxidant supplementation offers substantial pharmacological and therapeutic effects against various disease conditions. Astaxanthin is one such natural carotenoid with superior antioxidant activity than other carotenoids, as well as well as vitamins C and E, and additionally, it is known to exhibit a plethora of pharmacological effects. The present review summarizes the protective molecular mechanisms of actions of astaxanthin on age-related diseases of multiple organs such as Neurodegenerative diseases [Alzheimer's disease (AD), Parkinson's disease (PD), Stroke, Multiple Sclerosis (MS), Amyotrophic lateral sclerosis (ALS), and Status Epilepticus (SE)], Bone Related Diseases [Osteoarthritis (OA) and Osteoporosis], Cancers [Colon cancer, Prostate cancer, Breast cancer, and Lung Cancer], Cardiovascular disorders [Hypertension, Atherosclerosis and Myocardial infarction (MI)], Diabetes associated complications [Diabetic nephropathy (DN), Diabetic neuropathy, and Diabetic retinopathy (DR)], Eye disorders [Age related macular degeneration (AMD), Dry eye disease (DED), Cataract and Uveitis], Gastric Disorders [Gastritis, Colitis, and Functional dyspepsia], Kidney Disorders [Nephrolithiasis, Renal fibrosis, Renal Ischemia reperfusion (RIR), Acute kidney injury (AKI), and hyperuricemia], Liver Diseases [Nonalcoholic fatty liver disease (NAFLD), Alcoholic Liver Disease (AFLD), Liver fibrosis, and Hepatic Ischemia-Reperfusion (IR) Injury], Pulmonary Disorders [Pulmonary Fibrosis, Acute Lung injury (ALI), and Chronic obstructive pulmonary disease (COPD)], Muscle disorders (skeletal muscle atrophy), Skin diseases [Atopic dermatitis (ATD), Skin Photoaging, and Wound healing]. We have also briefly discussed astaxanthin's protective effects on reproductive health.

Protective capacity of carotenoid trans-astaxanthin in rotenone-induced toxicity in Drosophila melanogaster

Trans-astaxanthin (TA), a keto-carotenoid found in aquatic invertebrates, possesses anti-oxidative and anti-inflammatory activities. Rotenone is used to induce oxidative stress-mediated Parkinson’s disease (PD) in animals. We probed if TA would protect against rotenone-induced toxicity in Drosophila melanogaster. Trans-astaxanthin (0, 0.1, 0.5, 1.0, 2.5, 10, and 20 mg/10 g diet) and rotenone (0, 250 and 500 μM) were separately orally exposed to flies in the diet to evaluate longevity and survival rates, respectively. Consequently, we evaluated the ameliorative actions of TA (1.0 mg/10 g diet) on rotenone (500 μM)-induced toxicity in Drosophila after 7 days’ exposure. Additionally, we performed molecular docking of TA against selected pro-inflammatory protein targets. We observed that TA (0.5 and 1.0 mg/10 g diet) increased the lifespan of D. melanogaster by 36.36%. Moreover, TA (1.0 mg/10 g diet) ameliorated rotenone-mediated inhibition of Catalase, Glutathione-S-transferase and Acetylcholinesterase activities, and depletion of Total Thiols and Non-Protein Thiols contents. Trans-astaxanthin prevented behavioural dysfunction and accumulation of Hydrogen Peroxide, Malondialdehyde, Protein Carbonyls and Nitric Oxide in D. melanogaster (p < 0.05). Trans-astaxanthin showed higher docking scores against the pro-inflammatory protein targets evaluated than the standard inhibitors. Conclusively, the structural features of TA might have contributed to its protective actions against rotenone-induced toxicity.

Nanotechnology-Abetted Astaxanthin Formulations in Multimodel Therapeutic and Biomedical Applications

Astaxanthin (AXT) is one of the most important fat-soluble carotenoids that have abundant and diverse therapeutic applications namely in liver disease, cardiovascular disease, cancer treatment, protection of the nervous system, protection of the skin and eyes against UV radiation, and boosting the immune system. However, due to its intrinsic reactivity, it is chemically unstable, and therefore, the design and production processes for this compound need to be precisely formulated. Nanoencapsulation is widely applied to protect AXT against degradation during digestion and storage, thus improving its physicochemical properties and therapeutic effects. Nanocarriers are delivery systems with many advantages─ease of surface modification, biocompatibility, and targeted drug delivery and release. This review discusses the technological advancement in nanocarriers for the delivery of AXT through the brain, eyes, and skin, with emphasis on the benefits, limitations, and efficiency in practice.

Dietary agents in mitigating chemotherapy-related cognitive impairment (chemobrain or chemofog): first review addressing the benefits, gaps, challenges and ways forward

Chemobrain or chemofog is one of the important but less investigated side effects, where the cancer survivors treated with chemotherapy develop long-term cognitive impairments, affecting their quality of life. The biological mechanisms triggering the development of chemobrain are largely unknown. However, a literature study suggests the generation of free radicals, oxidative stress, inflammatory cytokines, epigenetic chromatin remodeling, decreased neurogenesis, secretion of brain-derived neurotropic factor (BDNF), dendritic branching, and neurotransmitter release to be the cumulative contributions to the ailment. Unfortunately, there is no means to prevent/mitigate the development and intensity of chemobrain. Given the lack of effective prevention strategies or treatments, preclinical studies have been underway to ascertain the usefulness of natural products in mitigating chemobrain in the recent past. Natural products used in diets have been shown to provide beneficial effects by inhibition of free radicals, oxidative stress, inflammatory processes, and/or concomitant upregulation of various cell survival proteins. For the first time, this review focuses on the published effects of astaxanthin, omega-3 fatty acids, ginsenoside, cotinine, resveratrol, polydatin, catechin, rutin, naringin, curcumin, dehydrozingerone, berberine, C-phycocyanin, the higher fungi Cordyceps militaris, thyme (Thymus vulgaris) and polyherbal formulation Mulmina™ in mitigating cognitive impairments in preclinical models of study, and also addresses their potential neuro-therapeutic mechanisms and applications in preventing/ameliorating chemobrain.

Astaxanthin Protects Testicular Tissue against Torsion/Detorsion-Induced Injury via Suppressing Endoplasmic Reticulum Stress in Rats

BACKGROUND

The aim of this study was to investigate the effects of astaxanthin (ASX) on testicular torsion/detorsion (T/D) damage in rats in terms of oxidative stress and endoplasmic reticulum (ER) stress.

METHODS

Eighteen male Sprague-Dawley rats were divided into three groups with six rats in each group: control, T/D and T/D + 20 mg/kg ASX. Torsion and detorsion times were applied as 4 h and 2 h, respectively. ASX application was performed 30 minutes before detorsion. At the end of the period, testicular tissues were removed and biochemical and histological analyzes were performed. To evaluate the degree of oxidative stress, tissue malondialdehyde (MDA), total oxidant status (TOS) and total antioxidant status (TAS) were determined using colorimetric methods, while tissue superoxide dismutase (SOD) levels were determined using ELISA kit. To evaluate the degree of ER stress, tissue glucose regulatory protein 78 (GRP78), activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP) levels were determined using ELISA kits. Johnsen's testicle scoring system was used for histological evaluation.

RESULTS

In the T/D group, it is determined that statistically significant decreasing in TAS, SOD levels and Johnsen score, and increasing in TOS, OSI, MDA, GRP78, ATF6 and CHOP levels (p < 0.001) compared with control group. ASX administration statistically significantly restored this T/D-induced damage (p < 0.01).

CONCLUSION

This is the first study to show that ASX prevent T/D-induced testicular damage through its antioxidant activity. More comprehensive studies are needed to see the underlying mechanisms.

Neuroprotective Effect of Ultrasound Triggered Astaxanthin Release Nanoparticles on Early Brain Injury After Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a fatal disease. Within 72 h of SAH, the intracranial blood-brain barrier (BBB) is destroyed, and the nerve cells have responses such as autophagy, apoptosis, and oxidative stress. Antioxidation is an essential treatment of SAH. Astaxanthin (ATX) induces cells' antioxidant behaviors by regulating related signal pathways to reduce the damage of brain oxidative stress, inflammation, and apoptosis. Because of its easy degradability and low bioavailability, ATX is mainly encapsulated with stimulus-responsive nanocarriers to improve its stability, making it rapidly release in the brain and efficiently enter the lesion tissue. In this study, the ultrasonic cavitation agent perfluorocarbon (PFH), ATX, and fluorescent dye IR780 were loaded with polydopamine (PDA) to prepare a US triggered release nanoparticles (AUT NPs). The core-shell structure of AUT NPs formed a physical barrier to improve the bioavailability of ATX. AUT NPs have high ATX loading capacity and US responsiveness. The experimental results show that the AUT NPs have high stability in the physiological environment. Both US and pH stimuli can trigger the release. Under US, PFH breaks through the rigid shell. The structure of AUT NPs is destroyed in situ, releasing the loaded drugs into neuronal cells to realize the antioxidant and antiapoptotic effects. The in vivo experiment results show that the AUT NPs have good biosafety. They release the drugs in the brain under stimuli. The in vivo treatment results also show that AUT NPs have an excellent therapeutic effect. This approach presents an experimental basis for the establishment of Innovative SAH treatments.

Microalgal protein AstaP is a potent carotenoid solubilizer and delivery module with a broad carotenoid binding repertoire

Carotenoids are lipophilic substances with many biological functions, from coloration to photoprotection. Being potent antioxidants, carotenoids have multiple biomedical applications, including the treatment of neurodegenerative disorders and retina degeneration. Nevertheless, the delivery of carotenoids is substantially limited by their poor solubility in the aqueous phase. Natural water-soluble carotenoproteins can facilitate this task, necessitating studies on their ability to uptake and deliver carotenoids. One such promising carotenoprotein, AstaP (astaxanthin-binding protein), was recently identified in eukaryotic microalgae, but its structure and functional properties remained largely uncharacterized. By using a correctly folded recombinant protein, here we show that AstaP is an efficient carotenoid solubilizer that can stably bind not only astaxanthin but also zeaxanthin, canthaxanthin, and, to a lesser extent, β-carotene, that is, carotenoids especially valuable to human health. AstaP accepts carotenoids provided as acetone solutions or embedded in membranes, forming carotenoid-protein complexes with an apparent stoichiometry of 1:1. We successfully produced AstaP holoproteins in specific carotenoid-producing strains of Escherichia coli, proving it is amenable to cost-efficient biotechnology processes. Regardless of the carotenoid type, AstaP remains monomeric in both apo- and holoform, while its rather minimalistic mass (~ 20 kDa) makes it an especially attractive antioxidant delivery module. In vitro, AstaP transfers different carotenoids to liposomes and to unrelated proteins from cyanobacteria, which can modulate their photoactivity and/or oligomerization. These findings expand the toolkit of the characterized carotenoid binding proteins and outline the perspective of the use of AstaP as a unique monomeric antioxidant nanocarrier with an extensive carotenoid binding repertoire.

Chronic Stress and Oxidative Stress as Common Factors of the Pathogenesis of Depression and Alzheimer's Disease: The Role of Antioxidants in Prevention and Treatment

There is a growing body of scientific research showing the link between depression and dementia in Alzheimer’s disease (AD). The chronic stress contributes to the formation of oxidative stress in the parts of the brain involved in the development of depression and AD. The scientific literature reports the significant role of antioxidants, which are highly effective in treating these diseases. In this review, we have summarized the relationship between chronic stress, oxidative stress, and the changes in the brain they cause occurring in the brain. Among all the compounds showing antioxidant properties, the most promising results in AD treatment were observed for Vitamin E, coenzyme Q10 (CoQ10), melatonin, polyphenols, curcumin, and selenium. In case of depression treatment, the greatest potential was observed in curcumin, zinc, selenium, vitamin E, and saffron.

The Role of Astaxanthin on Chronic Diseases

Natural astaxanthin exists widely in algae, fungi, shrimp and crab, and, as a strong antioxidant, has potential effects on cardiovascular diseases, cancer, liver diseases and other physical health diseases. The treatment of many diseases involves the body’s signal transduction to regulate the body’s antioxidant defense system and inflammation. Astaxanthin is usually used as a dietary supplement, which plays an antioxidant and anti-inflammatory role in the organism. This article reviews the structure, source of astaxanthin and how it plays an anti-inflammatory and anti-oxidant role in organisms, especially in treating diabetes.

Astaxanthin ameliorates oxidative stress and neuronal apoptosis via SIRT1/NRF2/Prx2/ASK1/p38 after traumatic brain injury in mice

BACKGROUND AND PURPOSE

Oxidative stress and neuronal apoptosis play key roles in traumatic brain injury. We investigated the protective effects of astaxanthin against traumatic brain injury and its underlying mechanisms of action.

EXPERIMENTAL APPROACH

A weight-drop model of traumatic brain injury in vivo and hydrogen peroxide exposure in vitro model were established. Brain oedema, behaviour tests, western blot, biochemical analysis, lesion volume, histopathological study and cell viability were performed.

KEY RESULTS

Astaxanthin significantly reduced oxidative insults on Days 1, 3 and 7 after traumatic brain injury. Neuronal apoptosis was also ameliorated on Day 3. Additionally, astaxanthin improved neurological functions up to 3 weeks after traumatic brain injury. Astaxanthin treatment dramatically enhanced the expression of peroxiredoxin 2 (Prx2), nuclear factor-erythroid 2-related factor 2 (NRF2/Nrf2) and sirtuin 1 (SIRT1), while it down-regulated the phosphorylation of apoptosis signal-regulating kinase 1 (ASK1) and p38. Inhibition of Prx2 by siRNA injection reversed the beneficial effects of astaxanthin against traumatic brain injury. Additionally, Nrf2 knockout prevented the neuroprotective effects of astaxanthin in traumatic brain injury. In contrast, overexpression of Prx2 in Nrf2 knockout mice attenuated the secondary brain injury after traumatic brain injury. Moreover, inhibiting SIRT1 by EX527 dramatically inhibited the neuroprotective effects of astaxanthin and suppressed SIRT1/Nrf2/Prx2/ASK1/p38 pathway both in vivo and in vitro.

CONCLUSION AND IMPLICATIONS

Astaxanthin improved the neurological functions and protected the brain from injury after traumatic brain injury, primarily by reducing oxidative stress and neuronal death via SIRT1/Nrf2/Prx2/ASK1/p38 signalling pathway and might be a new candidate to ameliorate traumatic brain injury.

Carotenoid Metabolism in Terrestrial Animals

Terrestrial animals, especially insects, contain various carotenoids that show structural diversity. These animals accumulated carotenoids derived from plants and other animals and modified them through metabolic reactions. Therefore, most of the carotenoids found in terrestrial animals originated from plants. Conversely, recent investigation revealed that some species of aphids and spider mites synthesized carotenoid themselves by carotenoid biosynthetic genes, which were horizontally transferred from fungi. In this chapter, carotenoids in terrestrial animals are described from the viewpoints of natural product chemistry, metabolism, food chain, and chemosystematics.

Astaxanthin protects cognitive function of vascular dementia

OBJECTIVE

The purpose of this study was to evaluate the effect of astaxanthin (AST) on cognition function, inflammatory response and oxidative stress in vascular dementia (VD) mice.

METHOD

VD mice model was established by left unilateral common carotid arteries occlusion (LUCCAO). Following LUCCAO, AST was intragastrically administered for 30 days. Object recognition test and morris water maze test were used to evaluate cognitive function. Hematoxylin and eosin staining was performed to observe the hippocampal neuron structure. Enzyme-linked immunosorbent assay kit and bicinchoninic acid kit were respectively adopted to measure IL-1β and IL-4 protein expression and superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in hippocampus and prefrontal cortex.

RESULTS

AST improved the discrimination ability of VD mice. The escape latency and path length of VD mice treated with AST were dramatically reduced. Besides, AST 200 mg/kg enhanced crossing platform time and the number of times crossing the platform quadrant, and alleviated the morphological impairment in VD mice. Moreover, we found that AST inhibited IL-1β expression and MDA content, whereas promoted IL-4 expression and SOD activity in a dose-dependent manner.

CONCLUSION

AST could improve cognitive impairment and hippocampal neurons in VD mice, which may be related to suppression of inflammatory response and oxidative stress.

Cognitive Effects of Astaxanthin Pretreatment on Recovery From Traumatic Brain Injury

Traumatic brain injury (TBI), caused by mechanical impact to the brain, is a leading cause of death and disability among young adults, with slow and often incomplete recovery. Preemptive treatment strategies may increase the injury resilience of high-risk populations such as soldiers and athletes. In this work, the xanthophyll carotenoid Astaxanthin was examined as a potential nutritional preconditioning method in mice (sabra strain) to increase their resilience prior to TBI in a closed head injury (CHI) model. The effect of Astaxanthin pretreatment on heat shock protein (HSP) dynamics and functional outcome after CHI was explored by gavage or free eating (in pellet form) for 2 weeks before CHI. Assessment of neuromotor function by the neurological severity score (NSS) revealed significant improvement in the Astaxanthin gavage-treated group (100 mg/kg, ATX) during recovery compared to the gavage-treated olive oil group (OIL), beginning at 24 h post-CHI and lasting throughout 28 days (p < 0.007). Astaxanthin pretreatment in pellet form produced a smaller improvement in NSS vs. posttreatment at 7 days post-CHI (p < 0.05). Cognitive and behavioral evaluation using the novel object recognition test (ORT) and the Y Maze test revealed an advantage for Astaxanthin administration via free eating vs. standard chow during recovery post-CHI (ORT at 3 days, p < 0.035; improvement in Y Maze score from 2 to 29 days, p < 0.02). HSP profile and anxiety (open field test) were not significantly affected by Astaxanthin. In conclusion, astaxanthin pretreatment may contribute to improved recovery post-TBI in mice and is influenced by the form of administration.

Astaxanthin Protects Retinal Photoreceptor Cells against High Glucose-Induced Oxidative Stress by Induction of Antioxidant Enzymes via the PI3K/Akt/Nrf2 Pathway

Diabetic retinopathy (DR) is a major microvascular complication that can lead to severe visual impairment in patients with diabetes. The elevated oxidative stress and increased reactive oxygen species (ROS) production induced by hyperglycemia have been reported to play an important role in the complex pathogenesis of DR. Astaxanthin (AST), a natural carotenoid derivative, has been recently recognized as a strong free radical scavenger and might, therefore, be beneficial in different diseases, including DR. In this study, we evaluated the potential role of AST as an antioxidative and antiapoptotic agent in protecting retinal cells and also investigated the involvement of the PI3K/Akt/Nrf2 pathway in AST-mediated effects. We treated high glucose-cultured mouse photoreceptor cells (661W) with different concentrations of AST and analyzed ROS production and cell apoptosis in the different regimens. Moreover, we also analyzed the expression of PI3K, Akt, Nrf2, and Phase II enzymes after AST treatment. Our results showed that AST dose-dependently reduced ROS production and attenuated 661W cell apoptosis in a high glucose environment. Importantly, its protective effect was abolished by treatment with PI3K or Nrf2 inhibitors, indicating the involvement of the PI3K/Akt/Nrf2 pathway. These results suggest AST as a nutritional supplement that could benefit patients with DR.

Anti-Apoptotic Effects of Carotenoids in Neurodegeneration

Apoptosis, programmed cell death type I, is a critical part of neurodegeneration in cerebral ischemia, Parkinson’s, and Alzheimer’s disease. Apoptosis begins with activation of pro-death proteins Bax and Bak, release of cytochrome c and activation of caspases, loss of membrane integrity of intracellular organelles, and ultimately cell death. Approaches that block apoptotic pathways may prevent or delay neurodegenerative processes. Carotenoids are a group of pigments found in fruits, vegetables, and seaweeds that possess antioxidant properties. Over the last several decades, an increasing number of studies have demonstrated a protective role of carotenoids in neurodegenerative disease. In this review, we describe functions of commonly consumed carotenoids including lycopene, β-carotene, lutein, astaxanthin, and fucoxanthin and their roles in neurodegenerative disease models. We also discuss the underlying cellular mechanisms of carotenoid-mediated neuroprotection, including their antioxidant properties, role as signaling molecules, and as gene regulators that alleviate apoptosis-associated brain cell death.

Astaxanthin Protects PC12 Cells against Homocysteine- and Glutamate-Induced Neurotoxicity

Memory impairment has been shown to be associated with glutamate (Glu) excitotoxicity, homocysteine (Hcy) accumulation, and oxidative stress. We hypothesize that Glu and Hcy could damage neuronal cells, while astaxanthin (ATX) could be beneficial to alleviate the adverse effects. Using PC12 cell model, we showed that Glu and Hcy provoked a huge amount of reactive oxygen species (ROS) production, causing mitochondrial damage at EC₅₀ 20 and 10 mm, respectively. The mechanisms of action include: (1) increasing calcium influx; (2) producing ROS; (3) initiating lipid peroxidation; (4) causing imbalance of the Bcl-2/Bax homeostasis; and (5) activating cascade of caspases involving caspases 12 and 3. Conclusively, the damages caused by Glu and Hcy to PC12 cells can be alleviated by the potent antioxidant ATX.

The Role of the Reactive Oxygen Species Scavenger Agent, Astaxanthin, in the Protection of Cisplatin-Treated Patients Against Hearing Loss

Emerging evidence of significant hearing loss occurring shortly after cisplatin administration in cancer patients has stimulated research into the causes and treatment of this side effect. Although the aetiology of cisplatin-induced hearing loss (CIHL) remains unknown, an increasing body of research suggests that it is associated with excessive generation of intracellular reactive oxygen species (ROS) in the cochlea. Astaxanthin, a xanthophyll carotenoid, has powerful anti-oxidant, anti-inflammatory, and anti-apoptotic properties based on its unique cell membrane function, diverse biological activities, and ability to permeate the blood-brain barrier. In this review, we summarize the role of ROS in CIHL and the effect of astaxanthin on inhibiting ROS production. We focus on investigating the mechanism of action of astaxanthin in suppressing excessive production of ROS.

Astaxanthin Ameliorates Ischemic-Hypoxic-Induced Neurotrophin Receptor p75 Upregulation in the Endothelial Cells of Neonatal Mouse Brains

Ischemic stroke is a leading cause of human death in present times. Two phases of pathological impact occur during an ischemic stroke, namely, ischemia and reperfusion. Both periods include individual characteristic effects on cell injury and apoptosis. Moreover, these conditions can cause severe cell defects and harm the blood-brain barrier (BBB). Also, the BBB components are the major targets in ischemia-reperfusion injury. The BBB owes its enhanced protective roles to capillary endothelial cells, which maintain BBB permeability. One of the nerve growth factor (NGF) receptors initiating cell signaling, once activated, is the p75 neurotrophin receptor (p75NTR). This receptor is involved in both the survival and apoptosis of neurons. Although many studies have attempted to explain the role of p75NTR in neurons, the mechanisms in endothelial cells remain unclear. Endothelial cells are the first cells to encounter p75NTR stimuli. In this study, we found the upregulated p75NTR expression and reductive expression of tight junction proteins after in vivo and in vitro ischemia-reperfusion injury. Moreover, astaxanthin (AXT), an antioxidant drug, was utilized and was found to reduce p75NTR expression and the number of apoptotic cells. This study verified that p75NTR plays a prominent role in endothelial cell death and provides a novel downstream target for AXT.

Xanthophyll: Health benefits and therapeutic insights

Xanthophylls constitute a major part of carotenoids in nature. They are an oxidized version of carotenoid. Xanthophyll has widely drawn scientists' attentions in terms of its functionality, bioavailability and diversity. An assortment of xanthophyll varieties includes lutein, zeaxanthin, β-cryptoxanthin, capsanthin, astaxanthin, and fucoxanthin. Chemically, lutein and zeaxanthin are dipolar carotenoids with hydroxyl groups at both ends of their molecules that bestow hydrophilic properties to them. Hydrophilic affinity in lutein and zeaxanthin makes better bioavailability in reaction with singlet oxygen in water phase, whereas non-polar carotenoids have shown to have less efficiency in scavenging free radicals. Xanthophylls have been studied for their effects in a wide variety of diseases including neurologic, ophthalmologic, oral, allergic and immune diseases. This review highlights pharmaco-pharmaceutical applications of xanthophylls as well asits drug interactions with beta-carotene. Different types of xanthophylls have been shown to have neuroprotective effects. Fucoxanthin demonstrated potent antiplasmodial activity. Lutein and zeaxanthin prevent the progression of age related macular degeneration. They have also demonstrated promising effects on uveitis, retinitis pigmentosa, scleritis, cataracts, glaucoma, retinal ischemia and choroideremia. Astaxanthin showed to have skin protecting effects against ultraviolet light injury. Astaxanthin have anti-allergic activity against the contact dermatitis especially to treat the patients having adverse reactions induced by steroids. Astaxanthin has been reported to exert beneficial effects in preventing oral lichen planus and early stage cancers. β-cryptoxanthin has been considered a good candidate for prevention of bone loss via osteoblastic bone formation and inhibiting osteoclastic bone resorption. There is also some concern that higher dose of xanthophylls may be linked to increased risk of skin cancer and gastric adenocarcinoma. However this increased risk was not statistically significant when adjusted for confounding factors. Further researches including clinical studies are needed to better evaluate the efficacy and safety of xanthophylls in prevention and treatment of different diseases.

Effect of Chronic Krill Oil Supplement on Seizures Induced by Pentylenetetrazole in the Hippocampus of Adult Rats with Previous Febrile Seizures

We evaluated the effect of krill oil (KO) supplement on seizures induced by pentylenetetrazole (PTZ) in animals with previous febrile seizures (FSs) induced by hyperthermia to determine its effectiveness in seizure susceptibility and as an anticonvulsant. Male Wistar rats with FS separated into water (W, 1 mL), palm oil (PO, 300 mg/kg, total volume 1 mL), or KO (300 mg/kg, total volume 1 mL) groups. All drugs were administered chronically via the intragastric route. Electrical activity was recorded by intracranial EEG simultaneously with convulsive behavior. All animals' brains were processed by immunofluorescence against GFAP, NeuN, and connexins (Cx); cellular quantification was performed in hippocampus and pyramidal or granular layer thickness was evaluated with cresyl violet (CV) staining. The results showed a significant delay in convulsive behavior and a slight increased survival time after PTZ administration in the group treated with KO compared with PO and W groups. The epileptiform activity showed high amplitude and frequency, with no significant differences between groups, nor were there differences in the number and duration of discharge trains. KO and PO increased the number of astrocytes and the number of neurons compared with the W group. KO and PO decreased the expression of Cx36 without affecting Cx43 expression or the thickness of layers. Based on these data, we consider it important to perform more experiments to determine the anticonvulsant role of KO, taking into account the partial effect found in this study. KO could be used as a coadjuvant of traditional anticonvulsive treatments. PRACTICAL APPLICATION: In this study was evaluated the anticonvulsive effect of a chronic krill oil (KO) supplement in animals with seizures. Results showed that KO had partial anticonvulsive effects measured by EEG activity and convulsive behavior analysis. These data justify further research that looks at KO supplementation as a prospective coadjuvant of pharmacologic management of seizure disorder.

Astaxanthin Complexes to Attenuate Muscle Damage after In Vivo Femoral Ischemia-Reperfusion

(1) Background: Reperfusion injury refers to the cell and tissue damage induced, when blood flow is restored after an ischemic period. While reperfusion reestablishes oxygen supply, it generates a high concentration of radicals, resulting in tissue dysfunction and damage. Here, we aimed to challenge and achieve the potential of a delivery system based on astaxanthin, a natural antioxidant, in attenuating the muscle damage in an animal model of femoral hind-limb ischemia and reperfusion. (2) Methods: The antioxidant capacity and non-toxicity of astaxanthin was validated before and after loading into a polysaccharide scaffold. The capacity of astaxanthin to compensate stress damages was also studied after ischemia induced by femoral artery clamping and followed by varied periods of reperfusion. (3) Results: Histological evaluation showed a positive labeling for CD68 and CD163 macrophage markers, indicating a remodeling process. In addition, higher levels of Nrf2 and NQO1 expression in the sham group compared to the antioxidant group could reflect a reduction of the oxidative damage after 15 days of reperfusion. Furthermore, non-significant differences were observed in non-heme iron deposition in both groups, reflecting a cell population susceptible to free radical damage. (4) Conclusions: Our results suggest that the in situ release of an antioxidant molecule could be effective in improving the antioxidant defenses of ischemia/reperfusion (I/R)-damaged muscles.

Astaxanthin inhibits homocysteine‑induced endothelial cell dysfunction via the regulation of the reactive oxygen species‑dependent VEGF‑VEGFR2‑FAK signaling pathway

Increased plasma levels of homocysteine (Hcy) can cause severe damage to vascular endothelial cells. Hcy‑induced endothelial cell dysfunction contributes to the occurrence and development of human cerebrovascular diseases (CVDs). Our previous studies have revealed that astaxanthin (ATX) exhibits novel cardioprotective activity against Hcy‑induced cardiotoxicity in vitro and in vivo. However, the protective effect and mechanism of ATX against Hcy‑induced endothelial cell dysfunction requires further investigation. In the present study, treatment of human umbilical vascular endothelial cells (HUVECs) with Hcy inhibited the migration, invasive and tube formation potentials of these cells in a dose‑dependent manner. Hcy treatment further induced a time‑dependent increase in the production of reactive oxygen species (ROS), and downregulated the expression of vascular endothelial growth factor (VEGF), phosphorylated (p)‑Tyr‑VEGF receptor 2 (VEGFR2) and p‑Tyr397‑focal adhesion kinase (FAK). On the contrary, ATX pre‑treatment significantly inhibited Hcy‑induced cytotoxicity and increased HUVEC migration, invasion and tube formation following Hcy treatment. The mechanism of action may involve the effective inhibition of Hcy‑induced ROS generation and the recovery of FAK phosphorylation. Collectively, our findings suggested that ATX could inhibit Hcy‑induced endothelial dysfunction by suppressing Hcy‑induced activation of the VEGF‑VEGFR2‑FAK signaling axis, which indicates the novel therapeutic potential of ATX in treating Hcy‑mediated CVD.

Astaxanthin prevents against lipopolysaccharide-induced acute lung injury and sepsis via inhibiting activation of MAPK/NF-κB

BACKGROUND

Endotoxin-induced acute inflammatory diseases such as sepsis, mediated by excessive production of various pro-inflammatory cytokines remain the leading cause of mortality in critically ill patients. Lipopolysaccharide (LPS), the characteristic endotoxin found in the outer membrane of Gram-negative bacteria, can induce the innate immunity system and through Mitogen activated protein kinase (MAPK) and Nuclear Factor-κB (NF-κB), increase the production of inflammatory mediators. Astaxanthin (ASX), a xanthophyll carotenoid, exerts beneficial effects against oxidation, inflammation, and cancer. But poor evidence has been reported that whether it has protective effects on LPS-induced injury. This study aims to investigate the effects of ASX on LPS-induced sepsis and acute lung injury and to demonstrate its mechanisms.

METHODS

Mouse prime macrophage (MPM) challenged with LPS were used for in vitro pharmacological activity and mechanistic studies. Inflammatory facors (tumor necrosis factor-alpha and interleukin-6 levels) in MPM were determined. The mouse models of LPS-induced sepsis and acute lung injury administrated with or without the compound were used for in vivo studies.

RESULTS

Pre-treatment of MPM with ASX inhibited MAPK/NF-κB signaling pathway, and attenuated LPS-increased inflammatory factors in vitro. In animal models of LPS-induced sepsis and acute lung injury, administration of ASX significantly improved survival and protected lung injury. Subsequently, ASX was shown to suppress LPS-induced inflammatory factors increase, MAPK phosphorylation, and NF-κB activation in vivo.

CONCLUSIONS

ASX exerts impressively protective effects on LPS-induced injury in vitro and in vivo. Taken together, it might be used as a potential candidate for clinical sepsis.

Effects of astaxanthin on sensory-motor function in a compression model of spinal cord injury: Involvement of ERK and AKT signalling pathway

BACKGROUND

Spinal cord injury (SCI) causes continuous neurological deficits and major sensory-motor impairments. There is no effective treatment to enhance sensory-motor function following SCI. Thus, it is crucial to develop novel therapeutics for this particular patient population. Astaxanthin (AST) is a strong antioxidant, anti-inflammatory and anti-apoptotic agent. In the present study, it was tested in a severe compression SCI model with emphasis on sensory-motor outcomes, signalling pathway, along with other complications.

METHODS

A severe SCI was induced by compression of the rat thoracic spinal cord with an aneurysm clip and treatment with AST or the vehicle was carried out, 30 min after injury. Behavioural tests including open field, von Frey, hot plate and BBB were performed weekly to 28 days post-injury. Rats were assigned to measure blood glucose, weight and auricle temperature. Western blot and histological analysis also were performed at the same time points.

RESULTS

AST decreased mechanical and thermal pain and also improved motor function performance, reduced blood glucose and auricle temperature increases and attenuated weight loss in SCI rats. Western blot analysis showed decreased activation of ERK1/2 and increased activation of AKT following AST treatment. The histology results revealed that AST considerably preserved myelinated white matter and the number of motor neurons following SCI.

CONCLUSION

Taken together, the beneficial effects of AST to improve sensory-motor outcomes, attenuate pathological tissue damage and modulate ERK and AKT signalling pathways following SCI, suggest it as a strong therapeutic agent towards clinical applications.

SIGNIFICANCE

Spinal cord injury (SCI) impairs sensory-motor function and causes complications, which astaxanthin (AST) has the potential to be used as a treatment for. The present study investigates the effects of AST in a compression model of SCI with emphasis on sensory-motor outcomes alongside other complications, histopathological damage and also related signalling pathways.

Reversal of homocysteine-induced neurotoxicity in rat hippocampal neurons by astaxanthin: evidences for mitochondrial dysfunction and signaling crosstalk

Elevated plasma level of homocysteine (Hcy) represents an independent risk for neurological diseases, and induction of oxidative damage is considered as one of the most important pathomechanisms. Astaxanthin (ATX) exhibits strong antioxidant activity in kinds of experimental models. However, the potential of ATX against Hcy-induced neurotoxicity has not been well explored yet. Herein, the neuroprotective effect of ATX against Hcy-induced neurotoxicity in rat hippocampal neurons was examined, and the underlying mechanism was evaluated. The results showed that ATX pre-treatment completely reversed Hcy-induced neurotoxicity through inhibiting cell apoptosis in rat primary hippocampal neurons. The mechanical investigation revealed that ATX effectively blocked Hcy-induced mitochondrial dysfunction by regulating Bcl-2 family and opening of mitochondrial permeability transition pore (MPTP). ATX pre-treatment also attenuated Hcy-induced oxidative damage via inhibiting the release of intracellular reactive oxide species (ROS) and superoxide anion through regulating MPTP opening. Moreover, normalization of MAPKs and PI3K/AKT pathways also contributed to ATX-mediated protective effects. Taken together, these results above suggested that ATX has the potential to reverse Hcy-induced neurotoxicity and apoptosis by inhibiting mitochondrial dysfunction, ROS-mediated oxidative damage and regulation of MAKPs and AKT pathways, which validated the strategy of using ATX could be a highly effective way in combating Hcy-mediated neurological disorders.

Astaxanthin attenuates neuroinflammation contributed to the neuropathic pain and motor dysfunction following compression spinal cord injury

Spinal cord injury (SCI) is a debilitating condition in which inflammatory responses in the secondary phase of injury leads to long lasting sensory-motor dysfunction. The medicinal therapy of SCI complications is still a clinical challenge. Understanding the molecular pathways underlying the progress of damage will help to find new therapeutic candidates. Astaxanthin (AST) is a ketocarotenoid which has shown anti-inflammatory effects in models of traumatic brain injury. In the present study, we examined its potential in the elimination of SCI damage through glutamatergic-phospo p38 mitogen-activated protein kinase (p-p38MAPK) signaling pathway. Inflammatory response, histopathological changes and sensory-motor function were also investigated in a severe compression model of SCI in male rats. The results of acetone drop and inclined plane tests indicated the promising role of AST in improving sensory and motor function of SCI rats. AST decreased the expression of n-methyl-d-aspartate receptor subunit 2B (NR2B) and p-p38MAPK as inflammatory signaling mediators as well as tumor necrosis factor-α (TNF-α) as an inflammatory cytokine, following compression SCI. The histopathological study culminated in preserved white mater and motor neurons beyond the injury level in rostral and caudal parts. The results show the potential of AST to inhibit glutamate-initiated signaling pathway and inflammatory reactions in the secondary phase of SCI, and suggest it as a promising candidate to enhance functional recovery after SCI.

Effects of Dietary Supplementation of Astaxanthin and Sesamin on Daily Fatigue: A Randomized, Double-Blind, Placebo-Controlled, Two-Way Crossover Study

Severe fatigue can negatively affect quality of life, and oxidative stress may play a role in its mechanism. The aim of this study was to evaluate the effect of dietary supplementation of astaxanthin and sesamin (AS), strong food-derived antioxidants, on fatigue. Twenty-four healthy volunteers were supplemented with AS and placebo, each for four weeks. After each supplementation period, participants underwent tasks inducing mental and physical fatigue (visual display terminal task and ergometer task, respectively). Subjective fatigue was evaluated using a visual analogue scale during and after the mental and physical tasks, and daily subjective fatigue was evaluated by the Chalder fatigue questionnaire. Secondary outcomes included other subjective feelings, work efficiency, autonomic nerve activity, levels of an oxidative stress marker (plasma phosphatidylcholine hydroperoxide (PCOOH)) and safety. AS supplementation was associated with significantly improved recovery from mental fatigue compared with placebo. Increased PCOOH levels during mental and physical tasks were attenuated by AS supplementation. No differences between AS and placebo were detected in secondary outcomes, and no adverse effects of AS supplementation were observed. In conclusion, AS supplementation may be a candidate to promote recovery from mental fatigue which is experienced by many healthy people.

Astaxanthin-antioxidant impact on excessive Reactive Oxygen Species generation induced by ischemia and reperfusion injury

Oxidative stress induced by Reactive Oxygen Species (ROS) was shown to be involved in the pathogenesis of chronic diseases such as cardiovascular pathologies. Particularly, oxidative stress has proved to mediate abnormal platelet function and dysfunctional endothelium-dependent vasodilatation representing a key factor in the progression of ischemic injuries. Antioxidants like carotenoids have been suggested to contribute in their prevention and treatment. Astaxanthin, a xanthophyll carotenoid produced naturally and synthetically, shows interesting antioxidant and anti-inflammatory properties. In vivo studies applying different models of induced ischemia and reperfusion (I/R) injury confirm astaxanthin's protective action after oral or intravenous administration. However, some studies have shown some limitations after oral administration such as low stability, bioavailability and bioefficacy, revealing a need for the implementation of new biomaterials to act as astaxanthin vehicles in vivo. Here, a brief overview of the chemical characteristics of astaxanthin, the carrier systems developed for overcoming its delivery drawbacks and the animal studies showing its potential effect to treat I/R injury are presented.

Astaxanthin prevents ischemia-reperfusion injury of the steatotic liver in mice

Steatosis has a low tolerance against ischemia-reperfusion injury (IRI). To prevent IRI in the steatotic liver, we attempted to elucidate the protective effect of astaxanthin (ASTX) in the steatotic liver model by giving mice a methionine and choline-deficient high fat (MCDHF) diet. Levels of lipid peroxidation and apoptosis, the expression of inflammatory cytokines and heme oxygenase (HO)-1, in the liver were assessed. Reactive oxygen species (ROS), inflammatory cytokines, apoptosis-related proteins and members of the signaling pathway were also examined in isolated Kupffer cells and/or hepatocytes from the steatotic liver. ASTX decreased serum ALT and AST levels, the amount of TUNEL, F4/80, or 4HNE-positive cells and the mRNA levels of inflammatory cytokines in MCDHF mice by IRI. Moreover, HO-1 and HIF-1α, phosphorylation of Akt and mTOR expressions were increased by ASTX. The inflammatory cytokines produced by Kupffer, which were subjected to hypoxia and reoxygenation (HR), were inhibited by ASTX. Expressions of Bcl-2, HO-1 and Nrf2 in hepatocytes by HR were increased, whereas Caspases activation, Bax and phosphorylation of ERK, MAPK, and JNK were suppressed by ASTX. Pretreatment with ASTX has a protective effect and is a safe therapeutic treatment for IRI, including for liver transplantation of the steatotic liver.

Astaxanthin protects astrocytes against trauma-induced apoptosis through inhibition of NKCC1 expression via the NF-κB signaling pathway

BACKGROUND

Astaxanthin (ATX) is a carotenoid pigment with pleiotropic pharmacological properties that is seen as a possible drug for treating cerebral ischemic injury and subarachnoid hemorrhage. Na⁺-K⁺-2Cl^- co-transporter-1 (NKCC1), an intrinsic membrane protein expressed by many cell types, is activated by various insults, leading to the formation of cell swelling and brain edema. We previously established that ATX attenuated brain edema and improved neurological outcomes by modulating NKCC1 expression after traumatic brain injury in mice. This paper explored the molecular mechanism of ATX-mediated inhibition of NKCC1 utilizing an in vitro astrocyte stretch injury model.

RESULTS

Stretch injury in cultured astrocytes lowered cell viability time-dependently, which was substantially reducing by pretreating with ATX (50 μmol/L). Stretch injury increased Bax level and cleaved caspase-3 activity, and decreased Bcl-2 level and pro-caspase 3 activity, resulting in the apoptosis of astrocytes. Additionally, stretch injury substantially raised the gene and protein expressions of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α and prompted the expression and nuclear translocation of NF-κB. Pretreatment with ATX remarkably prevented the trauma-induced initiation of NF-κB, expressions of pro-inflammatory cytokines, and cell apoptosis. Moreover, stretch injury markedly elevated the gene and protein expression of NKCC1, which was partly blocked by co-treatment with ATX (50 µmol/L) or an NF-κB inhibitor (PDTC, 10 µmol/L). Cleaved caspase-3 activity was partially reduced by PDTC (10 µmol/L) or an NKCC1 inhibitor (bumetanide, 50 µmol/L).

CONCLUSIONS

ATX attenuates apoptosis after stretch injury in cultured astrocytes by inhibiting NKCC1 expression, and it acts by reducing the expression of NF-κB-mediated pro-inflammatory factors.

Neuroprotective effects of astaxanthin in a rat model of spinal cord injury

Spinal cord injury (SCI) often leads to constant neurological deficits and long-term unalterable disability. Apoptosis plays an important role in the initiation of the secondary injury cascades leading to progressive tissue damage and severely functional deficits after SCI. Although the primary mechanical destructive events cannot be reversed, a therapeutic intervention could be carried out in order to moderate the secondary injury damage several hours to weeks after injury. Astaxanthin (AST) is a strong antioxidant and anti-inflammatory agents with the potential to render anti-apoptotic and neuroprotective effects. In the current study, we examined the therapeutic potential of AST on adult rats after severe SCI contusion. Results of BBB scores showed that AST improved motor function after SCI compared to control groups. Western blot analysis showed reduced expression of Bax and Cleaved-caspase-3 proteins and increased expression of the Bcl-2 protein in response to AST treatment (p<0.05). The histology results also showed that AST considerably preserved myelinated white matter and the number of motor neurons. This study is the first to report that AST reduces neuronal apoptosis, diminishes pathological tissue damage and improves functional recovery after SCI. The observed prominent neuroprotective effects, introduces AST as a promising therapy for SCI.

Astaxanthin attenuates glutamate-induced apoptosis via inhibition of calcium influx and endoplasmic reticulum stress

Astaxanthin (AST) is a carotenoid that has been shown to have neuroprotective effects. In this study, it was found that AST significantly inhibited glutamate-induced loss of cell viability and apoptosis. AST pretreatment attenuated glutamate-induced activation of caspase-3, reduction of anti-apoptotic protein Bcl-2, and increase of pro-apoptotic protein Bak. In addition, AST pretreatment suppressed the production of intracellular reactive oxygen species. AST treatment also prevented glutamate-induced increase of the level of activated p38 mitogen-activated protein kinase (MAPK), which has been shown to promote apoptotic events. Furthermore, AST treatment greatly reduced the elevation of intracellular calcium level induced by glutamate and inhibited the activity of calpain, a calcium-dependent protease that plays an important role in mediating apoptosis stimulated by calcium overload in cytoplasm. Both oxidative stress and calcium overload can lead to endoplasmic reticulum (ER) stress. C/EBP-homologous protein (CHOP) is a bZIP transcription factor that can be activated by ER stress and promotes apoptosis. Here we found that AST attenuated glutamate-induced elevation of CHOP and ER chaperone glucose-regulated protein (GRP78). Overall, these results suggested that AST might protect cells against glutamate-induced apoptosis through maintaining redox balance and inhibiting glutamate-induced calcium influx and ER stress.

Protective effect of an astaxanthin nanoemulsion against neomycin-induced hair-cell damage in zebrafish

Objective

The cause of those hair cells disorder is oxidative stress due to free radicals. In particular, hair cells are very susceptible to aminoglycosides. Antioxidant is known to reduce the generation of oxygen-derived free radicals. Various antioxidant is marketed, and different dosage form is developed with the same drug. Using a zebra fish lateral line, we report hair cell protection effect of astaxanthin from neomycin-induced trauma.

Methods

Zebrafish larvae were exposed to the astaxanthin nanoemulsion or to the suspension for 1 h, or were left unexposed. Subsequently, the larvae were exposed to neomycin for 1 h by adding the neomycin solution. Results were calculated as the mean hair-cell survival as a percentage of the control.

Results

Hair cells were not protected in the group treated with astaxanthin suspension and neomycin. On the other hand, there was dose-dependent protection against neomycin-induced hair-cell death in the zebrafish lateral-line hair cells in the group treated with nano astaxanthin.

Conclusion

The results of the current study performed using a zebra fish lateral-line, nano astaxanthin protected sensory hair cells against neomycin-induced death. This suggests that nano-astaxanthin is more efficiently absorbed in the body than astaxanthin, and may be useful as a protective drug for the inner ear.

Neuroprotective mechanisms of astaxanthin: a potential therapeutic role in preserving cognitive function in age and neurodegeneration

Astaxanthin (AXT) is a carotenoid with multiple health benefits. It is currently marketed as a health supplement and is well known for its antioxidant capacity. Recent evidence has emerged to suggest a broad range of biological activities. The interest in this compound has increased dramatically over the last few years and many studies are now applying this molecule across many disease models. Results from the current research are beginning to come together to suggest neuroprotective properties including anti-inflammatory, anti-apoptotic, and antioxidant effects, as well as the potential to promote or maintain neural plasticity. These emergent mechanisms of actions implicate AXT as a promising therapeutic agent for neurodegenerative disease. This review will examine and extrapolate from the recent literature to build support for the use of AXT in mitigating neuropathy in normal aging and neurodegenerative disease.

Astaxanthin protects against early burn-wound progression in rats by attenuating oxidative stress-induced inflammation and mitochondria-related apoptosis

Burn-wound progression can occur in the initial or peri-burn area after a deep burn injury. The stasis zone has a higher risk of deterioration mediated by multiple factors but is also considered salvageable. Astaxanthin (ATX), which is extracted from some marine organisms, is a natural compound with a strong antioxidant effect that has been reported to attenuate organ injuries caused by traumatic injuries. Hence, we investigated the potential effects of ATX on preventing early burn-wound progression. A classic "comb" burn rat model was established in this study for histological and biological assessments, which revealed that ATX, particularly higher doses, alleviated histological deterioration in the stasis zone. Additionally, we observed dose-dependent improvements in oxidative stress and the release of inflammatory mediators after ATX treatment. Furthermore, ATX dose-dependently attenuated burn-induced apoptosis in the wound areas, and this effect was accompanied by increases in Akt and Bad phosphorylation and a downregulation of cytochrome C and caspase expression. In addition, the administration of Ly 294002 further verified the effect of ATX. In summary, we demonstrated that ATX protected against early burn-wound progression in a rat deep-burn model. This protection might be mediated by the attenuation of oxidative stress-induced inflammation and mitochondria-related apoptosis.

Astaxanthin in cardiovascular health and disease: mechanisms of action, therapeutic merits, and knowledge gaps

Cardiovascular disease is the main contributor to morbidity and mortality worldwide.

Astaxanthin improves cognitive performance in mice following mild traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) produces lasting neurological deficits that plague patients and physicians. To date, there is no effective method to combat the source of this problem. Here, we utilized a mild, closed head TBI model to determine the modulatory effects of a natural dietary compound, astaxanthin (AST). AST is centrally active following oral administration and is neuroprotective in experimental brain ischemia/stroke and subarachnoid hemorrhage (SAH) models. We examined the effects of oral AST on the long-term neurological functional recovery and histological outcomes following moderate TBI in a mice model.

METHODS

Male adult ICR mice were divided into 3 groups: (1) Sham+olive oil vehicle treated, (2) TBI+olive oil vehicle treated, and (3) TBI+AST. The olive oil vehicle or AST were administered via oral gavage at scheduled time points. Closed head brain injury was applied using M.A. Flierl weight-drop method. NSS, Rotarod, ORT, and Y-maze were performed to test the behavioral or neurological outcome. The brain sections from the mice were stained with H&E and cresyl-violet to test the injured lesion volume and neuronal loss. Western blot analysis was performed to investigate the mechanisms of neuronal cell survival and neurological function improvement.

RESULTS

AST administration improved the sensorimotor performance on the Neurological Severity Score (NSS) and rotarod test and enhanced cognitive function recovery in the object recognition test (ORT) and Y-maze test. Moreover, AST treatment reduced the lesion size and neuronal loss in the cortex compared with the vehicle-treated TBI group. AST also restored the levels of brain-derived neurotropic factor (BDNF), growth-associated protein-43 (GAP-43), synapsin, and synaptophysin (SYP) in the cerebral cortex, which indicates the promotion of neuronal survival and plasticity.

CONCLUSION

To the best of our knowledge, this is the first study to demonstrate the protective role and the underlining mechanism of AST in TBI. Based on these neuroprotective actions and considering its longstanding clinical use, AST should be considered for the clinical treatment of TBI.

Reducing excitoxicity with glutamate transporter-1 to treat stroke

The neurotransmitter glutamate is released following ischemic brain damage, and its excitotoxic effects contribute greatly to the development of stroke. Because this release of glutamate occurs within minutes, therapeutic drugs targeting the restriction of glutamate-induced excitotoxicity must be administered quickly following ischemic onset. Here, we evaluate an alternative research approach examining the overexpression of glutamate transporter 1 (GLT1) to reduce infarction and improve behavioral deficits induced by stroke in a rat model of stroke. Recent studies verify the role of glutamate overflow in the pathogenesis of stroke. The experimental approach evaluated glutamate clearance, following ischemia-induced overflow where the GLT had been genetically manipulated to be overexpressed in the ischemic region. A viral vector-mediated gene transfer approach activated the overexpression of GLT1 to successfully reduce ischemia-induced glutamate overflow, decrease cell death, and improve behavioral recovery among animal models. These findings further support the role of glutamate in the pathogenesis of stroke and the upregulation of endogenous GLT1 as a promising approach to protect against the effects of ischemic brain damage caused by glutamate excitotoxicity. This study is a review article. Referred literature in this paper has been listed in the references part. The datasets supporting the conclusions of this article are available online by searching the PubMed. Some original points in this article come from the laboratory practice in our research centers and our experiences.