Therapeutic Potentials of Microalgae in the Treatment of Alzheimer's Disease

Microalgae in the food-health nexus: Exploring species diversity, high-value bioproducts, health benefits, and sustainable market potential

Microalgae are valuable nutraceutical sources because of their nutrient-rich profiles and diverse bioactive compounds. This review provides a comprehensive analysis of marine and freshwater microalgae, emphasizing their species diversity, nutrient composition, and methods used for their extraction and processing. The health benefits of microalgal-based nutraceuticals have been explored, with evidence highlighting their role in managing diabetes, cancer, oxidative stress, inflammation, and obesity. Additionally, the sustainability and environmental benefits of marine and freshwater microalgal cultivation are discussed. The market potential for these nutraceuticals has been explored, underpinned by recent advancements in biotechnology, nanotechnology, and omics approaches. Despite their promising potential, challenges such as extraction efficiency, purification processes, and production scalability currently limit the widespread application of microalgae in nutraceuticals. However, recent advancements in biotechnology and omics approaches are driving innovations, addressing these limitations, and unlocking new possibilities. Furthermore, ongoing research and technological innovations suggest a bright future for the integration of marine microalgae into the nutraceutical industry, promoting both human health and environmental sustainability. This review also evaluates the growing market potential and economic viability of microalgal-based nutraceuticals, highlighting their growing demand and economic viability and providing a comprehensive understanding of the benefits, market potential, and technological advancements of marine and freshwater microalgae, fostering further innovation in this promising field.

Freshwater microalgae biomasses are a source of bioaccessible bioactive compounds and have antioxidant, antihypertensive, and antidiabetic activity

Due to their sustainable production, freshwater microalgae have received attention as an alternative food rich in nutrients and bioactive compounds. This work assessed the composition and bioaccessibility of amino acids (AA), fatty acids (FA), and phenolic compounds (PC) present in the Chlorella vulgaris, Spirulina platensis, Scenedesmus acuminatus, Desmodesmus maximus, and Tetraselmis sp. biomass, and their antioxidant, antihypertensive and antidiabetic in vitro activities. The microalgae had a similar profile of compounds, but the concentration varied significantly between species. Lysine was the most abundant essential AA and palmitic and oleic (ω9) acids were the main FA detected in all microalgae. Moreover, the bioaccessibility was higher than 70 % for most FA, while the bioaccessibility of PC was generally low (<20 %). All microalgae showed significant antidiabetic (∼20-54 % ⍺-amylase inhibition and ∼ 91 % to ∼96 % ⍺-glucosidase inhibition), antihypertensive (∼13-53 % ACE inhibition) and antioxidant (1313.10-1821.60 μM eq Trolox/g) potential. C. vulgaris showed a higher concentration and bioaccessibility of phenolic compounds, resulting in an increased antidiabetic activity (higher α-glucosidase inhibition). S. platensis showed higher concentrations of fatty acids (palmitic, palmitoleic, and linoleic). D. maximus was characterized by higher concentrations and bioaccessibility of amino acids and an increased antioxidant and antidiabetic activities. Finally, Tetraselmis sp. presented improved concentration of tyrosine and increased antihypertensive activity. Therefore, the results can support the application of microalgae biomass in new functional foods for delivering bioactive compounds, primarily essential AA and FA, targeting specific niches that benefit from their potential health advantages. Findings underscore the commercial applicability of microalgae-based products.

Bioactive Potential of Algae and Algae-Derived Compounds: Focus on Anti-Inflammatory, Antimicrobial, and Antioxidant Effects

Algae, both micro- and macroalgae, are recognized for their rich repository of bioactive compounds with potential therapeutic applications. These marine organisms produce a variety of secondary metabolites that exhibit significant anti-inflammatory, antioxidant, and antimicrobial properties, offering promising avenues for the development of new drugs and nutraceuticals. Algae-derived compounds, including polyphenols, carotenoids, lipids, and polysaccharides, have demonstrated efficacy in modulating key inflammatory pathways, reducing oxidative stress, and inhibiting microbial growth. At the molecular level, these compounds influence macrophage activity, suppress the production of pro-inflammatory cytokines, and regulate apoptotic processes. Studies have shown that algae extracts can inhibit inflammatory signaling pathways such as NF-κB and MAPK, reduce oxidative damage by activating Nrf2, and offer an alternative to traditional antibiotics by combatting bacterial infections. Furthermore, algae's therapeutic potential extends to addressing diseases such as cardiovascular disorders, neurodegenerative conditions, and cancer, with ongoing research exploring their efficacy in preclinical animal models. The pig model, due to its physiological similarities to humans, is highlighted as particularly suitable for validating the bioactivities of algal compounds in vivo. This review underscores the need for further investigation into the specific mechanisms of action and clinical applications of algae-derived biomolecules.

Microalgae Octapeptide IIAVEAGC Alleviates Oxidative Stress and Neurotoxicity in 6-OHDA-Induced SH-SY5Y Cells by Regulating the Nrf2/HO-1and Jak2/Stat3 Pathways

Neurodegenerative diseases are characterized by the progressive loss of selectively vulnerable populations of neurons, and many factors are involved in its causes. Neurotoxicity and oxidative stress, are the main related factors. The octapeptide Ile-Ile-Ala-Val-Glu-Ala-Gly-Cys (IEC) was identified from the microalgae Isochrysis zhanjiangensis and exhibited potential anti-oxidative stress activity. In this study, the stability of α-synaptic protein binding to IEC was modeled using molecular dynamics, and the results indicated binding stabilization within 60 ns. Oxidative stress in neurons is the major cause of α-synaptic protein congestion. Therefore, we next evaluated the protective effects of IEC against oxidative stress and neurotoxicity in 6-ohdainduced Parkinson's disease (PD) model SH-SY5Y cells in vitro. In oxidative stress, IEC appeared to increase the expression of the antioxidant enzymes HO-1 and GPX through the antioxidant pathway of Nrf2, and molecular docking of IEC with Nrf2 and GPX could generate hydrogen bonds. Regarding apoptosis, IEC protected cells by increasing the Bcl-2/Bax ratio, inhibiting the caspase cascade, acting on p53, and modulating the Jak2/Stat3 pathway. The results indicated that IEC exerted neuroprotective effects through the inhibition of α-synaptic protein aggregation and antioxidant activity. Therefore, microalgal peptides have promising applications in the prevention and treatment of neurodegenerative diseases.

Mechanism of Intestinal Epithelial Absorption and Electrophysiological Regulation of the Shrimp Peptide QMDDQ

We investigated the absorption mechanism of the shrimp peptide QMDDQ in small intestines, explored its physiological function in inhibiting neuronal hyperactivity, and verified its entry into the brain in vivo to display functional activity. The everted rat sac model and a Caco-2 paracellular absorption monolayer model were used, indicating that QMDDQ has a good absorption capacity with an apparent permeability coefficient (Papp) > 1 × 10-6 cm/s and the absorption of QMDDQ was concentration-dependent. When the concentration of QMDDQ was 1 mM and the transport time was 180 min, the highest absorption concentration of QMDDQ was 41.17 ± 3.48 μM (P < 0.05). The myosin light-chain kinase (MLCK)-specific inhibitor ML-7 and activator MPA, Western blotting, and immunofluorescence results showed that QMDDQ absorption takes place by mediating the MLCK-p-MLCK-MLC signaling pathway, reversibly opening the zonula occludens-1 (ZO-1), occludin in tight junctions (TJs), upregulating claudin-2 expression, and reaching targets through blood to inhibit neuronal overactivity. Results of fluorescence imaging in vivo verified that QMDDQ could enter the brain 4 h after oral administration. The results provide a theoretical foundation for the mechanism of paracellular absorption of active peptides and a starting point for the development of functional foods for Alzheimer's disease intervention.

Marine Microalgae Schizochytrium sp. S31: Potential Source for New Antimicrobial and Antibiofilm Agent

BACKGROUND

The rise of antibiotic-resistant bacteria necessitates the discovery of new, safe, and bioactive antimicrobial compounds. The antibacterial and antibiofilm activity of microalgae makes them a potential candidate for developing natural antibiotics to limit microbial infection in various fields.

OBJECTIVE

This study aimed to analyze the antibacterial effect of the methanolic extract of Schizochytrium sp. S31 microalgae by broth microdilution and spot plate assays.

METHODS

The antibacterial effects of Schizochytrium sp. S31 extract was studied on gramnegative pathogens, Pseudomonas aeruginosa, Escherichia coli 35218, Klebsiella pneumonia, which cause many different human infections, and the gram-positive pathogen Streptococcus mutans. At the same time, the antibiofilm activity of the Schizochytrium sp. S31 extract on Pseudomonas aeruginosa and Escherichia coli 35218 bacteria were investigated by crystal violet staining method.

RESULTS

Schizochytrium sp. S31 extract at a 60% concentration for 8 hours displayed the highest antibacterial activity against P. aeruginosa, E. coli 35218, and K. pneumonia, with a decrease of 87%, 92%, and 98% in cell viability, respectively. The experiment with Streptococcus mutans revealed a remarkable antibacterial effect at a 60% extract concentration for 24 hours, leading to a notable 93% reduction in cell viability. Furthermore, the extract exhibited a dose-dependent inhibition of biofilm formation in P. aeruginosa and E. coli 35218. The concentration of 60% extract was identified as the most effective dosage in terms of inhibition.

CONCLUSION

This research emphasizes the potential of Schizochytrium sp. S31 as a natural antibacterial and antibiofilm agent with promising applications in the pharmaceutical sectors. This is the first study to examine the antibacterial activity of Schizochytrium sp. S31 microalgae using broth microdilution, spot plate assays, and the antibiofilm activity by a crystal staining method. The findings of this study show that Schizochytrium sp. S31 has antibacterial and antibiofilm activities against critical bacterial pathogens.

A review on nonviral, nonbacterial infectious agents toxicity involved in neurodegenerative diseases

Neuronal death, decreased activity or dysfunction of neurotransmitters are some of the pathophysiological reasons for neurodegenerative diseases like Alzheimer's, Parkinson's and multiple sclerosis. Also, there is evidence for the role of infections and infectious agents in neurodegenerative diseases and the effect of some metabolites in microorganisms in the pathophysiology of these diseases. In this study, we intend to evaluate the existing studies on the role of infectious agents and their metabolites on the pathophysiology of neurodegenerative diseases. PubMed, Scopus, Google Scholar and Web of Science search engines were searched. Some infectious agents have been observed in neurodegenerative diseases. Also, isolations of some fungi and microalgae have an improving effect on Parkinson's and Alzheimer's.

Bioactive compounds by microalgae and potentials for the management of some human disease conditions

Microalgae biomasses are excellent sources of diverse bioactive compounds such as lipids, polysaccharides, carotenoids, vitamins, phenolics and phycobiliproteins. Large-scale production of these bioactive substances would require microalgae cultivation either in open-culture systems or closed-culture systems. Some of these bioactive compounds (such as polysaccharides, phycobiliproteins and lipids) are produced during their active growth phase. They appear to have antibacterial, antifungal, antiviral, antioxidative, anticancer, neuroprotective and chemo-preventive activities. These properties confer on microalgae the potential for use in the treatment and/or management of several neurologic and cell dysfunction-related disease conditions, including Alzheimer's disease (AD), AIDS and COVID-19, as shown in this review. Although several health benefits have been highlighted, there appears to be a consensus in the literature that the field of microalgae is still fledgling, and more research needs to be carried out to ascertain the mechanisms of action that underpin the effectiveness of microalgal compounds. In this review, two biosynthetic pathways were modeled to help elucidate the mode of action of the bioactive compounds from microalgae and their products. These are carotenoid and phycobilin proteins biosynthetic pathways. The education of the public on the importance of microalgae backed with empirical scientific evidence will go a long way to ensure that the benefits from research investigations are quickly rolled out. The potential application of these microalgae to some human disease conditions was highlighted.

Microalgae as a Source of Valuable Phenolic Compounds and Carotenoids

Microalgae are photosynthetic, eukaryotic organisms that are widely used in the industry as cell factories to produce valuable substances, such as fatty acids (polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), sterols (sitosterol), recombinant therapeutic proteins, carbohydrates, vitamins, phenolic compounds (gallic acid, quercetin), and pigments (β-carotene, astaxanthin, lutein). Phenolic compounds and carotenoids, including those extracted from microalgae, possess beneficial bioactivities such as antioxidant capacity, antimicrobial and immunomodulatory activities, and direct health-promoting effects, which may alleviate oxidative stress and age-related diseases, including cardiovascular diseases or diabetes. The production of valuable microalgal metabolites can be modified by using abiotic stressors, such as light, salinity, nutrient availability, and xenobiotics (for instance, phytohormones).

Microalgae as a potential therapeutic drug candidate for neurodegenerative diseases

Microalgae are highly photosynthetic unicellular organism that have increased demand in the recent days owing to the presence of valuable cellular metabolites. They are ubiquitous in terrestrial and aquatic habitats, rich in species diversity and are capable of generating significant biomass by efficiently using CO₂, light and other nutrients like nitrogen, phosphate etc., The microalgal biomass has upsurged in economic potential and is used as both food and feed in many countries across the world, accounting for more than 75 % of annual microalgal biomass production in the past decades. The microalgal cells are sustainable resource that synthesize various secondary metabolites such as carotenoids, polysaccharides, polyphenols, essential amino acids, sterols, and polyunsaturated fatty acids (PUFA). Microalgae and its derived compounds possess significant pharmacological and biological effects such as antioxidant, anti-inflammatory, anti-cancer, immunomodulatory and anti-obesity. Because of their potential health promoting properties, the utilization of microalgae and its derived substances in food, pharmaceutical and cosmetic industries has skyrocketed in recent years. In this context, the current review discusses about the benefits of microalgae and its bioactive compounds against several neurodegenerative disorders like Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS).

Dietary Feeding Lycopene, Citric Acid, and Chlorella Alleviated the Neurotoxicity of Polyethylene Microplastics in African Catfish (Clarias gariepinus)

A few studies assessed how natural products can protect fish from the neurotoxic effects of Microplastics (MPs). Therefore, the goal of this study was to look into the neurotoxicity of PE-MPs on the brain tissue of African catfish (C. gariepinus), and whether dietary feeding on Chlorella, citric acid, and lycopene could help alleviate their toxicity. Five groups of fish were used: The first group received a standard diet (control). The second group was fed 500 mg/kg PE-MP. The third group was fed PE-MP + lycopene (500 mg/kg diet). The fourth group was fed PE-MP + citric acid (30 g/kg diet). And the fifth group was fed PE-MP + Chlorella (50 g/kg diet) for 15 days. The activities of Acetylcholinesterase (Ach), Monoamine Oxidase (MAO), Aldehyde Oxidase (AO), and Nitric Oxide (NO), and the histological effect on brain tissues were then assessed. The activity of the four neurological biomarker enzymes investigated was altered significantly in fish subjected to PE-MP alone compared with the control group. For fish exposed to PE-MP with lycopene, citric acid, or Chlorella, the activities of these neurological enzymes significantly improved particularly with Chlorella compared with fish fed PE-MP individually. Histological investigations illustrated that being subjected to PE-MPs effected cellular alterations in the telencephalon, including diffuse distorted and degraded neurons, encephalomalacia, aggregated neuroglial cells (gliosis), as well as deformed and necrotic neurons, neuropil vacuolation (spongiosis), aggregated neuroglial cells (gliosis), pyknotic neurons, and shrunken Purkinje cells which were found in the cerebellum. Most histological alterations induced by exposure to PE-MP feeding were restored by dietary feeding on Chlorella, citric acid, and lycopene. Accordingly, this study recommends using citric acid, lycopene, and Chlorella as a natural remedy against MP neurotoxicity particularly with Chlorella.

Prospecting potential of endophytes for modulation of biosynthesis of therapeutic bioactive secondary metabolites and plant growth promotion of medicinal and aromatic plants

Medicinal and aromatic plants possess pharmacological properties (antidiabetes, anticancer, antihypertension, anticardiovascular, antileprosy, etc.) because of their potential to synthesize a wide range of therapeutic bioactive secondary metabolites. The concentration of bioactive secondry metabolites depends on plant species, local environment, soil type and internal microbiome. The internal microbiome of medicinal plants plays the crucial role in the production of bioactive secondary metabolites, namely alkaloids, steroids, terpenoids, peptides, polyketones, flavonoids, quinols and phenols. In this review, the host specific secondry metabolites produced by endophytes, their therapeutic properties and host-endophytes interaction in relation to production of bioactive secondry metaboloites and the role of endophytes in enhancing the production of bioactive secondry metabolites is discussed. How biological nitrogen fixation, phosphorus solubilization, micronutrient uptake, phytohormone production, disease suppression, etc. can play a vital role in enhacing the plant growth and development.The role of endophytes in enhancing the plant growth and content of bioactive secondary metabolites in medicinal and aromatic plants in a sustainable mode is highlighted.

Alzheimer’s Disease and Toxins Produced by Marine Dinoflagellates: An Issue to Explore

This paper examined the toxins naturally produced by marine dinoflagellates and their effects on increases in β-amyloid plaques along with tau protein hyperphosphorylation, both major drivers of Alzheimer’s disease (AD). This approach is in line with the demand for certain natural compounds, namely those produced by marine invertebrates that have the potential to be used in the treatment of AD. Current advances in AD treatment are discussed as well as the main factors that potentially affect the puzzling global AD pattern. This study focused on yessotoxins (YTXs), gymnodimine (GYM), spirolides (SPXs), and gambierol, all toxins that have been shown to reduce β-amyloid plaques and tau hyperphosphorylation, thus preventing the neuronal or synaptic dysfunction that ultimately causes the cell death associated with AD (or other neurodegenerative diseases). Another group of toxins described, okadaic acid (OA) and its derivatives, inhibit protein phosphatase activity, which facilitates the presence of phosphorylated tau proteins. A few studies have used OA to trigger AD in zebrafish, providing an opportunity to test in vivo the effectiveness of new drugs in treating or attenuating AD. Constraints on the production of marine toxins for use in these tests have been considered. Different lines of research are anticipated regarding the action of the two groups of toxins.

Sustained Functioning Impairments and Oxidative Stress with Neurobehavioral Dysfunction Associated with Oral Nicotine Exposure in the Brain of a Murine Model of Ehrlich Ascites Carcinoma: Modifying the Antioxidant Role of Chlorella vulgaris

Simple Summary

Nicotine is the major psychoactive component considered to underlie tobacco’s addictive nature, and its dependence has been linked to several drawbacks on behavior and brain health. The purpose of this study was to investigate the mechanisms triggered by oral nicotine that cause brain tissue damage, as well as the supportive role of Chlorella vulgaris microalgae supplementation in Ehrlich ascites carcinoma in mice. The results revealed pronounced neurobehavioral alterations, increased mortality rate, oxidative stress, DNA damage, and augmented inflammatory response in the brain tissue alongside the microstructural alteration caused by nicotine. Chlorella vulgaris was quite successful in reducing the negative effects of nicotine. It acts as an antioxidant anti-inflammatory and restores nearly normal tissue architectures. As a result, we believe it should be supplemented to cancer patients consuming regular nicotine doses.

Abstract

Background: This study provides a model for studying the mechanism(s) responsible for the nervous tissue damage and misfunctioning that occurred due to oral nicotine exposure, considered a stress factor, during the presence of Ehrlich ascites carcinoma bearing in the mouse model (EAC). The mitigating role of Chlorella vulgaris (CV) against nicotine-induced brain damage was evaluated. Methods: Eighty Swiss female mice were classified into four groups, these were the control, the CV group, the nicotine group(100 µg/kg), and the combination group. Oxidant/antioxidant status, proinflammatory cytokines levels, DNA damage, quantitative microscopical lesions, and Caspase 3, Bcl-2 proteins were assessed in the current study. Levels of dopamine (DA) and gamma-aminobutyric acid (GABA) were also evaluated. Results: Nicotine was found to cause pronounced neurobehavioral alterations, increase the mortalities oxidative stress DNA damage, and augment the inflammatory response in brain tissue alongside the microstructural alteration. The administration of CV with nicotine in EAC-bearing mice rescued the detrimental effects of nicotine. Conclusions: CV aids in reducing the harmful effects of nicotine and returns the conditions caused by nicotine to near-control levels. Thus, we are in favor of giving it to cancer patients who are taking daily dosages of nicotine even by smoking cigarettes or being exposed to second-hand smoke.

Applications of Phyto-Nanotechnology for the Treatment of Neurodegenerative Disorders

The strategies involved in the development of therapeutics for neurodegenerative disorders are very complex and challenging due to the existence of the blood-brain barrier (BBB), a closely spaced network of blood vessels and endothelial cells that functions to prevent the entry of unwanted substances in the brain. The emergence and advancement of nanotechnology shows favourable prospects to overcome this phenomenon. Engineered nanoparticles conjugated with drug moieties and imaging agents that have dimensions between 1 and 100 nm could potentially be used to ensure enhanced efficacy, cellular uptake, specific transport, and delivery of specific molecules to the brain, owing to their modified physico-chemical features. The conjugates of nanoparticles and medicinal plants, or their components known as nano phytomedicine, have been gaining significance lately in the development of novel neuro-therapeutics owing to their natural abundance, promising targeted delivery to the brain, and lesser potential to show adverse effects. In the present review, the promising application, and recent trends of combined nanotechnology and phytomedicine for the treatment of neurological disorders (ND) as compared to conventional therapies, have been addressed. Nanotechnology-based efforts performed in bioinformatics for early diagnosis as well as futuristic precision medicine in ND have also been discussed in the context of computational approach.

Microalgae as a Potential Functional Ingredient: Evaluation of the Phytochemical Profile, Antioxidant Activity and In-Vitro Enzymatic Inhibitory Effect of Different Species

The functional food market has been in a state of constant expansion due to the increasing awareness of the impact of the diet on human health. In the search for new natural resources that could act as a functional ingredient for the food industry, microalgae represent a promising alternative, considering their high nutritional value and biosynthesis of numerous bioactive compounds with reported biological properties. In the present work, the phytochemical profile, antioxidant activity, and enzymatic inhibitory effect aiming at different metabolic disorders (Alzheimer's disease, Type 2 diabetes, and obesity) were evaluated for the species Porphyridium purpureum, Chlorella vulgaris, Arthorspira platensis, and Nannochloropsis oculata. All the species presented bioactive diversity and important antioxidant activity, demonstrating the potential to be used as functional ingredients. Particularly, P. purpureum and N. oculata exhibited higher carotenoid and polyphenol content, which was reflected in their superior biological effects. Moreover, the species P. purpureum exhibited remarkable enzymatic inhibition for all the analyses.

Recent Advancements and Future Perspectives of Microalgae-Derived Pharmaceuticals

Microalgal cells serve as solar-powered factories that produce pharmaceuticals, recombinant proteins (vaccines and drugs), and valuable natural byproducts that possess medicinal properties. The main advantages of microalgae as cell factories can be summarized as follows: they are fueled by photosynthesis, are carbon dioxide-neutral, have rapid growth rates, are robust, have low-cost cultivation, are easily scalable, pose no risk of human pathogenic contamination, and their valuable natural byproducts can be further processed. Despite their potential, there are many technical hurdles that need to be overcome before the commercial production of microalgal pharmaceuticals, and extensive studies regarding their impact on human health must still be conducted and the results evaluated. Clearly, much work remains to be done before microalgae can be used in the large-scale commercial production of pharmaceuticals. This review focuses on recent advancements in microalgal biotechnology and its future perspectives.

Butylated hydroxyl-toluene, 2,4-Di-tert-butylphenol, and phytol of Chlorella sp. protect the PC12 cell line against H2O2-induced neurotoxicity

Oxidative stress is considered the main cause of cellular damage in a number of neurodegenerative disorders. One suitable ways to prevent cell damage is the use of the exogenous antioxidant capacity of natural products, such as microalgae. In the present study, four microalgae extracts, isolated from the Persian Gulf, were screened to analyze their potential antioxidant activity and free radical scavenging using ABTS, DPPH, and FRAP methods. The methanolic extracts (D1M) of green microalgae derived from Chlorella sp. exhibited potent free radical scavenging activity. In order to characterize microalgae species, microscopic observations and analysis of the expression of 18S rRNA were performed. The antioxidant and neuroprotective effects of D1M on H₂O₂-induced toxicity in PC12 cells were investigated. The results demonstrated that D1M significantly decreased the release of nitric oxide (NO), formation of intracellular reactive oxygen species (ROS), and the level of malondialdehyde (MDA), whereas it enhanced the content of glutathione (GSH), and activity of heme oxygenase 1 (HO-1), NAD(P)H: quinone oxidoreductase 1 (NQO1), and catalase (CAT) in PC12 cells exposed to H₂O₂. The pretreatment of D1M improved cell viability as measured by the MTT assay and invert microscopy, reduced cell apoptosis as examined by flow cytometry analysis, increased mitochondrial membrane potential (MMP), and diminished caspase-3 activity. The GC/MS analysis revealed that D1M ingredients have powerful antioxidant and anti-inflammatory compounds, such as butylated hydroxytoluene (BHT), 2,4-di-tert-butyl-phenol (2,4-DTBP), and phytol. These results suggested that Chlorella sp. extracts have strong potential to be applied as neuroprotective agents, for the treatment of neurodegenerative disorders.

Marine Algae-Derived Bioactive Compounds: A New Wave of Nanodrugs?

Marine algae are rich in bioactive nutraceuticals (e.g., carbohydrates, proteins, minerals, fatty acids, antioxidants, and pigments). Biotic (e.g., plants, microorganisms) and abiotic factors (e.g., temperature, pH, salinity, light intensity) contribute to the production of primary and secondary metabolites by algae. Easy, profitable, and sustainable recovery methods include novel solid-liquid and liquid-liquid extraction techniques (e.g., supercritical, high pressure, microwave, ultrasound, enzymatic). The spectacular findings of algal-mediated synthesis of nanotheranostics has attracted further interest because of the availability of microalgae-based natural bioactive therapeutic compounds and the cost-effective commercialization of stable microalgal drugs. Algal extracts can serve as stabilizing/capping and reducing agents for the synthesis of thermodynamically stable nanoparticles (NPs). Different types of nanotherapeutics have been synthesized using physical, chemical, and biological methods. Marine algae are a fascinating source of lead theranostics compounds, and the development of nanotheranostics has been linked to enhanced drug efficacy and safety. Indeed, algae are remarkable nanobiofactories, and their pragmatic properties reside in their (i) ease of handling; (ii) capacity to absorb/accumulate inorganic metallic ions; (iii) cost-effectiveness; and (iv) capacity of eco-friendly, rapid, and healthier synthesis of NPs. Preclinical and clinical trials shall enable to really define effective algal-based nanotherapies. This review aims to provide an overview of the main algal compounds that are nutraceuticals and that can be extracted and purified for nanotheranostic purposes.

Chemical Characterization, Antiproliferative and Antioxidant Activities of Polyunsaturated Fatty Acid-Rich Extracts from Chlorella sp. S14

Microalgae is a rich source of polyunsaturated fatty acid. This study was conducted to identify and isolate microalgal strain with the potentials for producing polyunsaturated fatty acids (PUFAs) and determine its cytotoxic effect on some cancer cells. The algal strain (Chlorella sp. S14) was cultivated using modified BG-11 media, and algal biomass obtained was used for fatty acid extraction. Gas chromatographic–mass spectrometry was used to identify and quantify the levels of the fatty acid constituents. The total content of monounsaturated fatty acids (1.12%) was low compared to polyunsaturated fatty acids (PUFAs) (52.87%). Furthermore, n-3 PUFAs accounted for (12.37%) of total PUFAs with the presence of α-linolenic acid (2.16%) and cis-11,14,17-eicosatrienoic acid (2.16%). The PUFA-rich extract did not exhibit a cytotoxic effect on normal cells. Treatment with the PUFA-rich extract (150 µg/mL) significantly reduced cell viability in MCF-7 (31.58%) and A549 (62.56%) cells after the 48 h treatment. Furthermore, treatment of MCF-7 with fatty acid extracts (125 and 150 µg/mL) showed a significant reduction in MDA levels, increase in catalase activities and decrease in GSH level compared to untreated cells. However, a slight decrease in MDA level was observed in A549 cells after the 48 h treatment. There are no significant changes in catalase activities and GSH level in treated A549 cells. However, a slight reduction of NO levels was observed in treated MCF-7 and A549 cells. These results indicate the potentials of PUFA-rich extracts from Chlorella sp. S14 to reduce viability and modulate redox status in A549 and MCF-7 cells.

Bridging Cyanobacteria to Neurodegenerative Diseases: A New Potential Source of Bioactive Compounds against Alzheimer's Disease

Neurodegenerative diseases (NDs) represent a drawback in society given the ageing population. Dementias are the most prevalent NDs, with Alzheimer’s disease (AD) representing around 70% of all cases. The current pharmaceuticals for AD are symptomatic and with no effects on the progression of the disease. Thus, research on molecules with therapeutic relevance has become a major focus for the scientific community. Cyanobacteria are a group of photosynthetic prokaryotes rich in biomolecules with confirmed activity in pathologies such as cancer, and with feasible potential in NDs such as AD. In this review, we aimed to compile the research works focused in the anti-AD potential of cyanobacteria, namely regarding the inhibition of the enzyme β-secretase (BACE1) as a fundamental enzyme in the generation of β-amyloid (Aβ), the inhibition of the enzyme acetylcholinesterase (AChE) lead to an increase in the availability of the neurotransmitter acetylcholine in the synaptic cleft and the antioxidant and anti-inflammatory effects, as phenomena associated with neurodegeneration mechanisms.

Nutraceuticals-based therapeutic approach: recent advances to combat pathogenesis of Alzheimer's disease

Introduction: Alzheimer's disease (AD) is a progressive neurodegenerative disease accompanying memory deficits. The available pharmaceutical care has some limitations mostly entailing side effects, shelf-life, and patient's compliance. The momentous implications of nutraceuticals in AD have attracted scientists. Several preclinical studies for the investigation of nutraceuticals have been conducted.Areas covered: This review focuses on the potential use of a nutraceuticals-based therapeutic approach to treat and prevent AD. Increasing knowledge of AD pathogenesis has led to the discovery of new therapeutic targets including pathophysiological mechanisms and various cascades. Hence, the present contribution will attend to the most popular and effective nutraceuticals with proposed brief mechanisms entailing antioxidant, anti-inflammatory, autophagy regulation, mitochondrial homeostasis, and more. Therefore, even though the effectiveness of nutraceuticals cannot be dismissed, it is essential to do further high-quality randomized clinical trials.Expert opinion: According to the potential of nutraceuticals to combat AD as multi-target directed drugs, there is critical importance to assess them as feasible lead compounds for drug discovery and development. To the best of the authors' knowledge, modification of blood-brain barrier permeability, bioavailability, and features of randomized clinical trials should be considered in prospective studies.

A review of plant metabolites with metal interaction capacity: a green approach for industrial applications

Rapid industrial development is responsible for severe problems related to environmental pollution. Many human and industrial activities require different metals and, as a result, great amounts of metals/heavy metals are discharged into the water and soil making them dangerous for both human and ecosystems and this is being aggravated by intensive demand and utilization. In addition, compounds with metal binding capacities are needed to be used for several purposes including in activities related to the removal and/or recovery of metals from effluents and soils, as metals' corrosion inhibitors, in the synthesis of metallic nanoparticles and as metal related pharmaceuticals, preferably a with minimum risks associated to the environment. Plants are able to synthesize an uncountable number of compounds with numerous functions, including compounds with metal binding capabilities. In fact, some of the plants' secondary metabolites can bind to various metals through different mechanisms, as such they are excellent sources of such compounds due to their high availability and vast diversity. In addition, the use of plant-based compounds is desirable from an environmental and economical point of view, thus being potential candidates for utilization in different industrial activities, replacing conventional physiochemical methods. This review focuses on the ability of some classes of compounds that can be found in relatively high concentrations in plants, having good metal binding capacities and thus with potential utilization in metal based industrial activities and that can be involved in the progressive development of new environmentally friendly strategies.

Microbial Pathogenesis and Pathophysiology of Alzheimer's Disease: A Systematic Assessment of Microorganisms' Implications in the Neurodegenerative Disease

Microbial infections have been linked to the pathogenesis and pathophysiology of Alzheimer's disease (AD) and other neurodegenerative diseases. The present study aimed to synthesise and assess global evidence of microbial pathogenesis and pathophysiology in AD (MPP-AD) and associated neurodegenerative conditions using integrated science mapping and content analytics to explore the associated research landscape. Relevant MPP-AD documents were retrieved from Web of Science and Scopus according to PRISMA principles and analysed for productivity/trend linked to authors/countries, thematic conceptual framework, and international collaborative networks. A total of 258 documents published from 136 sources to 39.42 average citations/document were obtained on MPP-AD. The co-authors per document were 7.6, and the collaboration index was 5.71. The annual research outputs increased tremendously in the last 6 years from 2014 to 2019, accounting for 66% compared with records in the early years from 1982 to 1990 (16%). The USA (n = 71, freq. = 30.34%), United Kingdom (n = 32, freq. = 13.68%) and China (n = 27, 11.54%) ranked in first three positions in term of country's productivity. Four major international collaboration clusters were found in MPP-AD research. The country collaboration network in MPP-AD was characteristic of sparse interaction and acquaintanceship (density = 0.11, diameter = 4). Overall, international collaboration is globally inadequate [centralisation statistics: degree (40.5%), closeness (4%), betweenness (23%), and eigenvector (76.7%)] against the robust authors' collaboration index of 5.71 in MPP-AD research. Furthermore, four conceptual thematic frameworks (CTF) namely, CTF#1, roles of microbial/microbiome infection and dysbiosis in cognitive dysfunctions; CTF#2, bacterial infection specific roles in dementia; CTF#3, the use of yeast as a model system for studying MPP-AD and remediation therapy; and CFT#4, flow cytometry elucidation of amyloid-beta and aggregation in Saccharomyces cerevisiae model. Finally, aetiology-based mechanisms of MPP-AD, namely, gut microbiota, bacterial infection, and viral infection, were comprehensively discussed. This study provides an overview of MPP-AD and serves as a stepping stone for future preparedness in MPP-AD-related research.

Microalgal Cell Biofactory-Therapeutic, Nutraceutical and Functional Food Applications

Microalgae are multifaceted photosynthetic microorganisms with emerging business potential. They are present ubiquitously in terrestrial and aquatic environments with rich species diversity and are capable of producing significant biomass. Traditionally, microalgal biomass is being used as food and feed in many countries around the globe. The production of microalgal-based bioactive compounds at an industrial scale through biotechnological interventions is gaining interest more recently. The present review provides a detailed overview of the key algal metabolites, which plays a crucial role in nutraceutical, functional foods, and animal/aquaculture feed industries. Bioactive compounds of microalgae known to exhibit antioxidant, antimicrobial, antitumor, and immunomodulatory effects were comprehensively reviewed. The potential microalgal species and biological extracts against human pathogens were also discussed. Further, current technologies involved in upstream and downstream bioprocessing including cultivation, harvesting, and cell disruption were documented. Establishing microalgae as an alternative supplement would complement the sustainable and environmental requirements in the framework of human health and well-being.

Advantages of Heterotrophic Microalgae as a Host for Phytochemicals Production

Currently, most commercial recombinant technologies rely on host systems. However, each host has their own benefits and drawbacks, depending on the target products. Prokaryote host is lack of post-transcriptional and post-translational mechanisms, making them unsuitable for eukaryotic productions like phytochemicals. Even there are other eukaryote hosts (e.g., transgenic animals, mammalian cell, and transgenic plants), but those hosts have some limitations, such as low yield, high cost, time consuming, virus contamination, and so on. Thus, flexible platforms and efficient methods that can produced phytochemicals are required. The use of heterotrophic microalgae as a host system is interesting because it possibly overcome those obstacles. This paper presents a comprehensive review of heterotrophic microalgal expression host including advantages of heterotrophic microalgae as a host, genetic engineering of microalgae, genetic transformation of microalgae, microalgal engineering for phytochemicals production, challenges of microalgal hosts, key market trends, and future view. Finally, this review might be a directions of the alternative microalgae host for high-value phytochemicals production in the next few years.

Extraction, Properties, and Applications of Bioactive Compounds Obtained from Microalgae

With the increase in the global population, getting new sources of food is essential. One of the solutions can be found in the oceans due to algae. Microalgae are aquatic photosynthetic organisms used mainly due to their variety of bioactive compounds. The consumption of microalgae has been carried out for centuries and is recommended by organizations, such as OMS and FAO, due to its nutritional value and its properties. Based on the existing literature, there is substantial evidence of the nutritional quality of the algae as well as their functional elements. However, much quantification is still necessary, as well as studying possible adverse effects. The present review describes the compounds of alimentary interest present in these algae as well as different extraction techniques assisted by different energetic mechanisms (such as heat, supercritical-fluid, microwave, ultrasound, enzymes, electric field, high hydrostatic pressure, among others). The most challenging and crucial issues are reducing microalgae growth cost and optimizing extraction techniques. This review aimed a better understanding of the uses of microalgae for new researches in nutrition. Since the use of microalgae is still a field in which there is much to discover, it is likely that more benefits will be found in its consumption.

Influence of organic solvents in the extraction and purification of torularhodin from Sporobolomyces ruberrimus

OBJECTIVE

This work aimed at evaluating the influence of organic solvents and stationary phases in the extraction with glass beads and chromatographic purification of carotenoids, especially torularhodin, from Sporobolomyces ruberrimus.

RESULTS

The combinations of acetone:hexane (1:1 v/v) and acetone:ethyl ether (1:1 v/v) yielded 171.74 and 172.19 μg of total carotenoids.g of cells^-1, respectively. The first blend resulted in the highest percent of cell lysis of 57.4%. Among different proportions of acetone:hexane, the 9:1 v/v mixture showed a significant difference (p < 0.05), resulting in a recovery of total carotenoids of 221.88 μg.g of cells^-1. The purification of carotenoids was made by preparative chromatography and the yield of the silica-containing stationary phase was higher (24 μg torularhodin.g cells^-1). The analyses of the purified fractions in thin layer chromatography and high performance liquid chromatography indicated that the purification of carotenoids, especially of torularhodin, was successfully performed.

CONCLUSIONS

The combination of polar (acetone) and non-polar solvents (hexane) and the use of silica as stationary phase was efficient to recover and purify torularhodin from the intracellular pigments of Sporobolomyces ruberrimus.

Anti-Alzheimer's Materials Isolated from Marine Bio-resources: A Review

The most common type of dementia found in the elderly population is Alzheimer's disease. The disease not only impacts the patients and their families but also the society therefore, the main focus of researchers is to search new bioactive materials for treating AD. The marine environment is a rich source of functional ingredients and to date, we can find sufficient research relating to anti- Alzheimer's compounds isolated from marine environment. Therefore, this review focuses on the anti- Alzheimer's material from marine bio-resources and then expounds on the anti-Alzheimer's compounds from marine seaweed, marine animal and marine microorganisms. Moreover, because of the complexity of the disease, different hypothesizes have been elaborated and active compounds have been isolated to inhibit different stages of pathophysiological mechanisms. Sulfated polysaccharides, glycoprotein, and enzymatic hydrolysates from marine seaweeds, peptides, dietary omega-3 polyunsaturated fatty acids and skeletal polysaccharide from marine animals and secondary metabolites from marine microorganism are summarized in this review under the anti-Alzheimer's compounds from the marine.

Are Cyanotoxins the Only Toxic Compound Potentially Present in Microalgae Supplements? Results from a Study of Ecological and Non-Ecological Products

Food supplements with microalgae are becoming increasingly abundant and can be easily found anywhere. The most popular products are based on cyanophytes, such as Aphanizomenon flos-aquae, Arthrospira platensis and Limnospira maxima, or on chlorophytes, such as Chlorella or Haematoccus. Although they are all advertised as being very beneficial for health, these products might be harmful because they may contain cyanotoxins and other contaminants, and no information on production methods or strain origins is usually provided. While legislation on the presence of microcystins in waters for different uses is clear, toxicological analyses are not compulsory for food supplements, nor for analyzing anatoxins. Given the potential risk of eating contaminated food, cyanotoxins, heavy metals and the presence of other contaminant organisms were analyzed in 10 microalgae food supplements. Microcystin-LR and anatoxin-a were detected in three analyzed products, and in both cyanophyte- and chlorophyte-based products. The light microscope study revealed the presence of different potentially harmful microbial contaminants. The ICP (OES) analyses detected high concentrations of some heavy metals, especially Pb. The results emphasize the need to promote the better control of food products containing microalgae, and to develop standard methodologies to analyze cyanotoxins and potential toxic compounds to protect consumer health.

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

Background

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

Methods

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

Results

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

Conclusion

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

Microalgae: A Promising Source of Valuable Bioproducts

Microalgae are a group of autotrophic microorganisms that live in marine, freshwater and soil ecosystems and produce organic substances in the process of photosynthesis. Due to their high metabolic flexibility, adaptation to various cultivation conditions as well as the possibility of rapid growth, the number of studies on their use as a source of biologically valuable products is growing rapidly. Currently, integrated technologies for the cultivation of microalgae aiming to isolate various biologically active substances from biomass to increase the profitability of algae production are being sought. To implement this kind of development, the high productivity of industrial cultivation systems must be accompanied by the ability to control the biosynthesis of biologically valuable compounds in conditions of intensive culture growth. The review considers the main factors (temperature, pH, component composition, etc.) that affect the biomass growth process and the biologically active substance synthesis in microalgae. The advantages and disadvantages of existing cultivation methods are outlined. An analysis of various methods for the isolation and overproduction of the main biologically active substances of microalgae (proteins, lipids, polysaccharides, pigments and vitamins) is presented and new technologies and approaches aimed at using microalgae as promising ingredients in value-added products are considered.

Cholinesterase inhibitory activity, antioxidant properties, and phytochemical composition of Chlorococcum sp. extracts

In this study, Chlorococcum sp. was investigated for its cholinesterase inhibitory potentials and antioxidant activity. The algal sample was cultivated, harvested, and extracted sequentially using n-hexane, dichloromethane, and ethanol. The extracts were characterized using Fourier transmission infra-red (FTIR) and Gas Chromatography-Mass Spectrometry. The metal chelating, radical scavenging activities, as well as anticholinesterase potentials of the algal extract, was also investigated. FTIR characterization of the microalgal biomass revealed the presence of phenolic compounds, alkaloids, polysaccharides, and fatty acids. The extracts showed the presence of phytol, neophytadiene, butylated hydroxyl toluene, and 3-tert-butyl-4-hydroxyanisole. The ethanol extract showed the highest DPPH (IC₅₀  = 147.40 µg/ml) and OH (IC₅₀  = 493.90 µg/ml) radical scavenging and metal chelating (IC₅₀  = 83.25 µg/ml) activities. Similarly, the ethanol extract (IC₅₀  = 13.83 µg/ml) exhibited the highest acetylcholinesterase inhibitory activity, while the dichloromethane extract showed the highest butyrylcholinesterase inhibitory activity. All the extracts exhibited antioxidant properties and inhibitory effects against butyrylcholinesterase and acetylcholinesterase; however, ethanol extracts showed better activity. PRACTICAL APPLICATIONS: Biomass obtained from some microalgal species is commonly used as dietary supplements and nutraceuticals due to the presence of high-valued products. However, the antioxidant and anticholinesterase activities of biomass from Chlorococcum sp. have not been explored. Chlorococcum sp. extracts contain some antioxidants such as 3-tert-Butyl-4-hydroxyanisole, butylated hydroxytoluene, phytol, and neophytadiene. Characterization of the extracts also revealed the presence of phenolic compounds, polysaccharides, and fatty acids. These compounds may contribute to the observed antioxidant and anticholinesterase activities of Chlorococcum sp. The result of this study suggests that Chlorococcum sp. may contain some nutraceuticals which could be used as antioxidants and cholinesterase inhibitors.

Algae Metabolites in Cosmeceutical: An Overview of Current Applications and Challenges

Cosmetics are widely used by people around the world to protect the skin from external stimuli. Consumer preference towards natural cosmetic products has increased as the synthetic cosmetic products caused adverse side effects and resulted in low absorption rate due to the chemicals' larger molecular size. The cosmetic industry uses the term "cosmeceutical", referring to a cosmetic product that is claimed to have medicinal or drug-like benefits. Marine algae have gained tremendous attention in cosmeceuticals. They are one of the richest marine resources considered safe and possessed negligible cytotoxicity effects on humans. Marine algae are rich in bioactive substances that have shown to exhibit strong benefits to the skin, particularly in overcoming rashes, pigmentation, aging, and cancer. The current review provides a detailed survey of the literature on cosmeceutical potentials and applications of algae as skin whitening, anti-aging, anticancer, antioxidant, anti-inflammation, and antimicrobial agents. The biological functions of algae and the underlying mechanisms of all these activities are included in this review. In addition, the challenges of using algae in cosmeceutical applications, such as the effectiveness of different extraction methods and processing, quality assurance, and regulations concerning extracts of algae in this sector were also discussed.

Manganese-induced neurotoxicity and the potential protective effects of lipoic acid and Spirulina platensis

Manganese (Mn) is essential for many physiological processes; however, its excessive accumulation in the brain causes severe dysfunctions in the nervous system. Oxidative stress is thought to be involved in Mn-induced neurotoxicity. The aim of this study was to evaluate the neurotoxic effects of Mn and the potential protective effects of alpha lipoic acid (ALA) and Spirulina platensis (SP), each alone and in combination. Sixty-four male albino rats were divided into eight equal groups: group 1 was used as control, group 2 received saline, which used as a vehicle, group 3 received ALA (50 mg/kg/day), group 4 received SP (300 mg/kg/day), group 5 received Mn (74 mg/kg, 5 days/week), group 6 received Mn + ALA, group 7 received Mn + SP, group 8 received Mn + ALA + SP. Groups 6, 7 and 8 received the same previously mentioned doses. All treatments were orally gavaged for 8 weeks. Mn administration caused neurobehavioral changes, increases of brain and serum Mn and malondialdehyde (MDA), with decreased glutathione peroxidase (GPx), dopamine and acetylcholine levels. The co-treatment with ALA and SP revealed their ability to protect against oxidative damage, neurobehavioral and biochemical changes induced by Mn.

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

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

Potential utilization of bioproducts from microalgae for the quality enhancement of natural products

Microalgae are autotroph organisms that utilise light energy to synthesize various high-value bioactive compounds such as polysaccharides, proteins and lipids. Due to its fast growth rate and capability to survive in harsh environment, microalgae nowadays are applied in various industrial areas. The process of obtaining microalgae-based biomolecules starts with the selection of suitable microalgae strain, cultivation, followed by downstream processing of the biomass (i.e., pre-treatment, harvesting, extraction and purification). The end products of the processes are biofuels and other valuable bioproducts. Nevertheless, low production yield and high-cost downstream processes are the emerging bottlenecks which need to be addressed in the upscaling of extracted compounds from microalgae biomass. To conclude, tremendous efforts are required to overcome these challenges to revolutionize microalgae into a novel and green factory of different bioactive compounds for industrial necessities to satisfy and fulfil global demands.

Emerging Technologies in Algal Biotechnology: Toward the Establishment of a Sustainable, Algae-Based Bioeconomy

Mankind has recognized the value of land plants as renewable sources of food, medicine, and materials for millennia. Throughout human history, agricultural methods were continuously modified and improved to meet the changing needs of civilization. Today, our rapidly growing population requires further innovation to address the practical limitations and serious environmental concerns associated with current industrial and agricultural practices. Microalgae are a diverse group of unicellular photosynthetic organisms that are emerging as next-generation resources with the potential to address urgent industrial and agricultural demands. The extensive biological diversity of algae can be leveraged to produce a wealth of valuable bioproducts, either naturally or via genetic manipulation. Microalgae additionally possess a set of intrinsic advantages, such as low production costs, no requirement for arable land, and the capacity to grow rapidly in both large-scale outdoor systems and scalable, fully contained photobioreactors. Here, we review technical advancements, novel fields of application, and products in the field of algal biotechnology to illustrate how algae could present high-tech, low-cost, and environmentally friendly solutions to many current and future needs of our society. We discuss how emerging technologies such as synthetic biology, high-throughput phenomics, and the application of internet of things (IoT) automation to algal manufacturing technology can advance the understanding of algal biology and, ultimately, drive the establishment of an algal-based bioeconomy.

Health benefits and bioavailability of marine resources components that contribute to health - what's new?

The strict connection between nutritional intake and health leads to a necessity of understanding the beneficial and protective role of healthy nutrients and foods. The marine environment is a source of a plethora of many organisms with unique properties, extremely rich in bioactive compounds and with remarkable potential for medical, industrial and biotechnological applications. Marine organisms are an extreme valuable source of functional ingredients such as polysaccharides, vitamins, minerals, pigments, enzymes, proteins and peptides, polyunsaturated fatty acids (PUFA), phenolic compounds and other secondary metabolites that prevent or have the potential to treat several diseases given their cardiovascular protective, anti-inflammatory, anti-hypertensive, anti-oxidant, anti-coagulant, anti-proliferative and anti-diabetic activities. This review provides an overview on the current advances regarding health benefits of marine bioactive compounds on several diseases and on human gut microbiota. In addition, it is discussed a crucial factor that is related to the effectiveness of these compounds on human organism namely its real bioavailability.

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

Zinc plays an important role in neuronal signaling and neurotransmission. However, dyshomeostasis of this metal or its accumulation in the brain has been linked with neurological disorders such as Alzheimer's disease and Parkinson's disease. In this study, the neuroprotective effects of Ecklonia maxima (KPM), Gracilaria gracilis (GCL), Ulva lactuca (ULT) and Gelidium pristoides (MNP) in Zn -induced neurotoxicity in HT-22 cells was examined. Cells were treated with Zinc sulphate and/or aqueous - ethanol extracts and cell viability, apoptosis, acetylcholinesterase activity, including some antioxidant enzymes (catalase and superoxide dismutase activity) and glutathione (GSH) levels were determined. Malondialdehyde and nitric oxide levels produced in the Zn and/or seaweed extract treated cells were also determined. Prior treatment with the seaweed extracts improved cell viability and inhibited Zn - induced cell death. Acetylcholinesterase activity was significantly high in Zn treated cells compared to the control. Pre-treatment with the seaweed extracts triggered a decrease in acetylcholinesterase activity in Zn - treated cells. Furthermore, treatment with Zn caused a significant reduction in GSH levels as well as a decrease in superoxide dismutase and catalase activities. In contrast, the seaweed extract increased antioxidant enzyme activities and GSH levels. An increase in malondialdehyde and nitric oxide levels was also reversed after treatment with the seaweed extracts. These results suggest that the seaweed extracts improved cholinergic transmission disrupted by Zn - induced neurotoxicity and protected the cells against oxidative damage and neuroinflammation. The neuroprotective effects of the seaweed extracts could be linked to their bioactive constituents. Hence these seaweeds are potential sources of active ingredients with neuroprotective potentials and could be used for the development of functional foods and/or nutraceuticals.

Phenolic composition, antioxidant activity, anticholinesterase potential and modulatory effects of aqueous extracts of some seaweeds on β-amyloid aggregation and disaggregation

Context: Seaweeds contain bioactive compounds with different biological activities. They are used as functional ingredients for the development of therapeutic agents to combat degenerative diseases. Objective: This study investigated the phenolic composition, antioxidant activity, cholinesterase inhibitory and anti-amyloidogenic activities of aqueous extracts of Gracilaria beckeri (J.Agardh) Papenfuss (Gracilariaceae) (RED-AQ), Ecklonia maxima (Osbeck) Papenfuss (Lessoniaceae) (ECK-AQ), Ulva rigida (C.Agardh) Linnaeus (Ulvaceae) (URL-AQ) and Gelidium pristoides (Turner) Kützing (Gelidiaceae) (GEL-AQ). Materials and methods: Phenolic composition of the seaweed extracts was determined using liquid chromatography mass spectrometry. Radical scavenging and metal chelating activities were assessed in vitro. The effect of the extracts (21-84 µg/mL) on acetylcholinesterase and butyrylcholinesterase activities were also investigated using an in vitro colorimetric assay. Transmission electron microscope and thioflavin-T fluorescence assay were used to examine the anti-amyloidogenic activities of the extracts. Results: Phloroglucinol, catechin, epicatechin 3-glucoside were identified in the extracts. ECK-AQ (IC50=30.42 and 280.47 µg/mL) exhibited the highest OH• scavenging and metal chelating activities, while RED-AQ (41.23 and 334.45 µg/mL) exhibited the lowest. Similarly, ECK-AQ (IC50 = 49.41 and 52.11 µg/mL) exhibited higher inhibitory effects on acetylcholinesterase and butyrylcholinesterase activities, while RED-AQ (64.56 and 63.03 µg/mL) showed the least activities. Rapid formation of β-amyloid (Aβ1-42) fibrils and aggregates was observed in electron micrographs of the control after 72 and 96 h. The reduction of Aβ1-42 aggregates occurred after co-treatment with the seaweed extracts. Discussion and conclusion: ECK-AQ, GEL-AQ, URL-AQ and RED-AQ may possess neuroprotective potential and could be explored for the management of Alzheimer's disease.

Natural Compounds as Beneficial Antioxidant Agents in Neurodegenerative Disorders: A Focus on Alzheimer's Disease

The positive role of nutrition in chronic neurodegenerative diseases (NDs) suggests that dietary interventions represent helpful tools for preventing NDs. In particular, diets enriched with natural compounds have become an increasingly attractive, non-invasive, and inexpensive option to support a healthy brain and to potentially treat NDs. Bioactive compounds found in vegetables or microalgae possess special properties able to counteract oxidative stress, which is involved as a triggering factor in neurodegeneration. Here, we briefly review the relevant experimental data on curcuminoids, silymarin, chlorogenic acid, and compounds derived from the microalga Aphanizomenon flos aquae (AFA) which have been demonstrated to possess encouraging beneficial effects on neurodegeneration, in particular on Alzheimer's disease models.

Dunaliella salina microalgae oppose thioacetamide-induced hepatic fibrosis in rats

Several hepatic pathological conditions are correlated with the stimulation of hepatic stellate cells. This induces a cascade of events producing accretion of extracellular matrix components triggering fibrosis. Dunaliella salina, rich in carotenoids, was investigated for its potential antagonizing activity; functionally and structurally against thioacetamide (TAA) - induced hepatic fibrosis in rats. Adult male albino Wistar rats were treated with three dose levels of D. salina powder or extract (daily, p.o.); for 6 weeks, concomitantly with TAA injection. Serum levels of aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), bilirubin and albumin were determined. Reduced glutathione (GSH), malondialdehyde (MDA), smooth muscle actin alpha (α-SMA) and collagen I hepatic contents were also estimated. Treatment with D. salina powder or extract caused a significant decline in serum levels of AST, ALT, ALP, bilirubin, MDA and hepatic contents of α-SMA and collagen I. Additionally, serum albumin and GSH hepatic content were highly elevated. Liver histopathological examination also indicated that D. salina reduced fibrosis, centrilobular necrosis, and inflammatory cell infiltration evoked by TAA. The results implied that D. salina exerts protective action against TAA-induced hepatic fibrosis in rats. The phytochemical investigation revealed high total carotenoid content prominently β-carotene (15.2 % of the algal extract) as well as unsaturated fatty acids as alpha-linolenic acid which accounts for the hepatoprotective activity.

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

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

Aqueous-ethanol extracts of some South African seaweeds inhibit beta-amyloid aggregation, cholinesterases, and beta-secretase activities in vitro

In this study, we evaluated the anti-amyloidogenic, anticholinesterase, and antioxidant potentials of hydroethanolic extracts of Ecklonia maxima (ECK), Gelidium pristoides (GLD), Gracilaria gracilis (GCL), and Ulva lactuca (ULT). The effect of the extracts on β-amyloid (Aβ1-42 ) peptide were determined using electron microscope. The effects of the extracts on β-secretase and cholinesterase activities, as well as their radical scavenging and metal chelating activities were also assessed. Electron micrographs revealed that ECK, GLD, GCL, and ULT incubated with Aβ1-42 at different intervals (0-96 hr) showed very low levels of fibrils compared to the control. The extracts also inhibited β-secretase, acetylcholinesterase, and butyrylcholinesterase activities in a dose-dependent manner. Furthermore, the extracts scavenged hydroxyl radicals and were able to chelate Fe2+ in a dose-dependent manner. Our findings suggest that the seaweed extracts are potential sources of lead compounds and novel inhibitors of β-amyloid aggregation, β-secretase, and cholinesterases for the management of Alzheimer's diseases. PRACTICAL APPLICATIONS: Seaweeds have been identified as good sources of naturally occurring bioactive compounds with several medicinal properties. They are commonly used as functional foods and development of nutraceuticals, dietary supplements, and cosmeceuticals. However, the neuroprotective effects of many species of seaweeds have not been fully explored. The findings of this study suggests that Gracilaria gracilis, Ulva lactuca, Ecklonia maxima, and Gelidium pristoides are potential sources of cholinesterase, beta-secretase, and amyloid protein aggregation inhibitors. Hence, this support the use of these seaweeds as alternative sources of antioxidants and natural compounds with neuroprotective potentials for the management of Alzheimer's disease.