Astaxanthin ameliorates scopolamine-induced spatial memory deficit via reduced cortical-striato-hippocampal oxidative stress

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.

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

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

Combined Donepezil with Astaxanthin via Nanostructured Lipid Carriers Effective Delivery to Brain for Alzheimer's Disease in Rat Model

Introduction

Donepezil (DPL), a specific acetylcholinesterase inhibitor, is used as a first-line treatment to improve cognitive deficits in Alzheimer's disease (AD) and it might have a disease modifying effect. Astaxanthin (AST) is a natural potent antioxidant with neuroprotective, anti-amyloidogenic, anti-apoptotic, and anti-inflammatory effects. This study aimed to prepare nanostructured lipid carriers (NLCs) co-loaded with donepezil and astaxanthin (DPL/AST-NLCs) and evaluate their in vivo efficacy in an AD-like rat model 30 days after daily intranasal administration.

Methods

DPL/AST-NLCs were prepared using a hot high-shear homogenization technique, in vitro examined for their physicochemical parameters and in vivo evaluated. AD induction in rats was performed by aluminum chloride. The cortex and hippocampus were isolated from the brain of rats for biochemical testing and histopathological examination.

Results

DPL/AST-NLCs showed z-average diameter 149.9 ± 3.21 nm, polydispersity index 0.224 ± 0.017, zeta potential -33.7 ± 4.71 mV, entrapment efficiency 81.25 ±1.98% (donepezil) and 93.85 ±1.75% (astaxanthin), in vitro sustained release of both donepezil and astaxanthin for 24 h, spherical morphology by transmission electron microscopy, and they were stable at 4-8 ± 2°C for six months. Differential scanning calorimetry revealed that donepezil and astaxanthin were molecularly dispersed in the NLC matrix in an amorphous state. The DPL/AST-NLC-treated rats showed significantly lower levels of nuclear factor-kappa B, malondialdehyde, β-site amyloid precursor protein cleaving enzyme-1, caspase-3, amyloid beta (Aβ1‑42), and acetylcholinesterase, and significantly higher levels of glutathione and acetylcholine in the cortex and hippocampus than the AD-like untreated rats and that treated with donepezil-NLCs. DPL/AST-NLCs showed significantly higher anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, anti-inflammatory, and anti-apoptotic effects, resulting in significant improvement in the cortical and hippocampal histopathology.

Conclusion

Nose-to-brain delivery of DPL/AST-NLCs is a promising strategy for the management of AD.

Biological and neurological activities of astaxanthin (Review)

Astaxanthin is a lipid‑soluble carotenoid produced by various microorganisms and marine animals, including bacteria, yeast, fungi, microalgae, shrimps and lobsters. Astaxanthin has antioxidant, anti‑inflammatory and anti‑apoptotic properties. These characteristics suggest that astaxanthin has health benefits and protects against various diseases. Owing to its ability to cross the blood‑brain barrier, astaxanthin has received attention for its protective effects against neurological disorders, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, cerebral ischemia/reperfusion, subarachnoid hemorrhage, traumatic brain injury, spinal cord injury, cognitive impairment and neuropathic pain. Previous studies on the neurological effects of astaxanthin are mostly based on animal models and cellular experiments. Thus, the biological effects of astaxanthin on humans and its underlying mechanisms are still not fully understood. The present review summarizes the neuroprotective effects of astaxanthin, explores its mechanisms of action and draws attention to its potential clinical implications as a therapeutic agent.

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.

Natural Products for the Treatment of Neurodegenerative Diseases

Neurodegenerative diseases are a heterogeneous group of disorders characterized by the progressive degeneration of the structure and function of the central nervous system or peripheral nervous system. Alzheimer's Disease (AD), Parkinson's Disease (PD) and Spinal Cord Injury (SCI) are the common neurodegenerative diseases, which typically occur in people over the age of 60. With the rapid development of an aged society, over 60 million people worldwide are suffering from these uncurable diseases. Therefore, the search for new drugs and therapeutic methods has become an increasingly important research topic. Natural products especially those from the Traditional Chinese Medicines (TCMs), are the most important sources of drugs, and have received extensive interest among pharmacist. In this review, in order to facilitate further chemical modification of those useful natural products by pharmacists, we will bring together recent studies in single natural compound from TCMs with neuroprotective effect.

Attenuation of Nrf2/Keap1/ARE in Alzheimer's Disease by Plant Secondary Metabolites: A Mechanistic Review

Alzheimer’s disease (AD) is a progressive neuronal/cognitional dysfunction, leading to disability and death. Despite advances in revealing the pathophysiological mechanisms behind AD, no effective treatment has yet been provided. It urges the need for finding novel multi-target agents in combating the complex dysregulated mechanisms in AD. Amongst the dysregulated pathophysiological pathways in AD, oxidative stress seems to play a critical role in the pathogenesis progression of AD, with a dominant role of nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein-1 (Keap1)/antioxidant responsive elements (ARE) pathway. In the present study, a comprehensive review was conducted using the existing electronic databases, including PubMed, Medline, Web of Science, and Scopus, as well as related articles in the field. Nrf2/Keap1/ARE has shown to be the upstream orchestrate of oxidative pathways, which also ameliorates various inflammatory and apoptotic pathways. So, developing multi-target agents with higher efficacy and lower side effects could pave the road in the prevention/management of AD. The plant kingdom is now a great source of natural secondary metabolites in targeting Nrf2/Keap1/ARE. Among natural entities, phenolic compounds, alkaloids, terpene/terpenoids, carotenoids, sulfur-compounds, as well as some other miscellaneous plant-derived compounds have shown promising future accordingly. Prevailing evidence has shown that activating Nrf2/ARE and downstream antioxidant enzymes, as well as inhibiting Keap1 could play hopeful roles in overcoming AD. The current review highlights the neuroprotective effects of plant secondary metabolites through targeting Nrf2/Keap1/ARE and downstream interconnected mediators in combating AD.

Levocarnitine Improves AlCl3-Induced Spatial Working Memory Impairment in Swiss albino Mice

Background: Aluminum, a neurotoxic substance, causes oxidative stress induced-neurodegenerative diseases. Several lines of evidence suggest that levocarnitine has an antioxidant effect and also plays an important role in beta-oxidation of fatty acids. However, the role of levocarnitine in aluminum-induced neurotoxicity has not been well documented. Here we aimed to investigate the effect of levocarnitine on aluminum chloride (AlCl₃)-induced oxidative stress and memory dysfunction.

Methods: Male Swiss albino mice (n = 30) were treated with either control (saline) or AlCl₃ or AlCl₃ plus levocarnitine or levocarnitine or astaxanthin plus AlCl₃ or astaxanthin alone. The spatial working memory was determined by radial arm maze (RAM). In addition, we measured the lipid peroxidation (MDA), glutathione (GSH), advanced oxidation of protein products (AOPP), nitric oxide (NO) and activity of superoxide dismutase (SOD) in the various brain regions including prefrontal cortex (PFC), striatum (ST), parietal cortex (PC), hippocampus (HIP) hypothalamus (HT) and cerebellum (CB). We used astaxanthin as a standard antioxidant to compare the antioxidant activity of levocarnitine.

Results: The RAM data showed that AlCl₃ treatment (50 mg/kg) for 2 weeks resulted in a significant deficit in spatial learning in mice. Moreover, aluminum exposure significantly (p < 0.05) increased the level of oxidative stress markers such as MDA, GSH, AOPP and NO in the various brain regions compared to the controls. In addition, combined administration of levocarnitine and AlCl₃ significantly (p < 0.05) lowered the MDA, AOPP, GSH and NO levels in mice.

Conclusion: Our results demonstrate that levocarnitine could serve as a potential therapeutic agent in the treatment of oxidative stress associated diseases as well as in memory impairment.