Acetylcholinesterase inhibitory activity of phlorotannins isolated from the brown alga, Ecklonia maxima (Osbeck) Papenfuss

Phytochemical compounds with promising biological activities from Ascophyllum nodosum extracts using microwave-assisted extraction

Phytochemical-rich antioxidant extracts were obtained from Ascophyllum nodosum (AN) using microwave-assisted extraction (MAE). Critical extraction factors such as time, pressure, and ethanol concentration were optimized by response surface methodology with a circumscribed central composite design. Under the optimal MAE conditions (3 min, 10.4 bar, 46.8 % ethanol), the maximum recovery of phytochemical compounds (polyphenols and fucoxanthin) with improved antioxidant activity from AN was obtained. In addition, the optimized AN extract showed significant biological activities as it was able to scavenge reactive oxygen and nitrogen species, inhibit central nervous system-related enzymes, and exhibit cytotoxic activity against different cancer cell lines. In addition, the optimized AN extract showed antimicrobial, and anti-quorum sensing activities, indicating that this extract could offer direct and indirect protection against infection by pathogenic microorganisms. This work demonstrated that the sustainably obtained AN extract could be an emerging, non-toxic, and natural ingredient with potential to be included in different applications.

Novel studies on Isolation, purification and characterization of dibenzonitro compound from Glycosmis pentaphylla (Retz.) DC. and effect in downregulating neuronal cancers

To isolate Letrozole from Glycosmis pentaphylla (Retz.) DC. and to determine its effect on regulating the proliferation, cell cycle distribution, apoptosis and key mechanisms in human neuroblastoma cell lines. Letrozole was isolated through column chromatographic technique and its effect was checked on human neuroblastoma cell lines, IMR 32. The effects of Letrozole on cell viability were measured by MTT assay, and the cell cycle distribution was determined by flow cytometry. The expression changes in mRNA of proliferating cell nuclear antigen (PCNA), cyclin D1 and Bcl-xL were taken from real-time PCR analysis and the protein levels were detected by Western blotting. The results of the present study showed that Letrozole, isolated from leaves of G. pentaphylla could cause significant inhibitory effect on proliferation of IMR 32 cells in a dose dependent manner. Cell arrest was obtained at S phase with the treatment of Letrozole. Apart from this, the expression of PCNA, cyclin D1 and Bcl-xL were decreased both at mRNA and protein levels for the same treatment. Letrozole can inhibit proliferation, induce cell arrest and cause apoptosis in IMR 32 cell lines. The decreased expression of PCNA, cyclin D1 and Bcl-xL induced by Letrozole contributes to the above effects in vitro. This is the first report on the isolation of Letrozole from G. pentaphylla.

Therapeutic effects of phlorotannins in the treatment of neurodegenerative disorders

Phlorotannins are natural polyphenolic compounds produced by brown marine algae and are currently found in nutritional supplements. Although they are known to cross the blood-brain barrier, their neuropharmacological actions remain unclear. Here we review the potential therapeutic benefits of phlorotannins in the treatment of neurodegenerative diseases. In mouse models of Alzheimer's disease, ethanol intoxication and fear stress, the phlorotannin monomer phloroglucinol and the compounds eckol, dieckol and phlorofucofuroeckol A have been shown to improve cognitive function. In a mouse model of Parkinson's disease, phloroglucinol treatment led to improved motor performance. Additional neurological benefits associated with phlorotannin intake have been demonstrated in stroke, sleep disorders, and pain response. These effects may stem from the inhibition of disease-inducing plaque synthesis and aggregation, suppression of microglial activation, modulation of pro-inflammatory signaling, reduction of glutamate-induced excitotoxicity, and scavenging of reactive oxygen species. Clinical trials of phlorotannins have not reported significant adverse effects, suggesting these compounds to be promising bioactive agents in the treatment of neurological diseases. We therefore propose a putative biophysical mechanism of phlorotannin action in addition to future directions for phlorotannin research.

Marine Macroalgae Polyphenols as Potential Neuroprotective Antioxidants in Neurodegenerative Diseases

Polyphenols are beneficial natural compounds with antioxidant properties that have recently gain a lot of interest for their potential therapeutic applications. Marine polyphenols derived from marine macroalgae have been discovered to possess interesting antioxidant properties; therefore, these compounds can be included in several areas of drug development. Authors have considered the use of polyphenol extracts from seaweeds as neuroprotective antioxidants in neurodegenerative diseases. Marine polyphenols may slow the progression and limit neuronal cell loss due to their antioxidant activity; therefore, the use of these natural compounds would improve the quality of life for patients affected with neurodegenerative diseases. Marine polyphenols have distinct characteristics and potential. Among seaweeds, brown algae are the main sources of polyphenols, and present the highest antioxidant activity in comparison to red algae and green algae. The present paper collects the most recent in vitro and in vivo evidence from investigations regarding polyphenols extracted from seaweeds that exhibit neuroprotective antioxidant activity. Throughout the review, oxidative stress in neurodegeneration and the mechanism of action of marine polyphenol antioxidant activity are discussed to evidence the potential of algal polyphenols for future use in drug development to delay cell loss in patients with neurodegenerative disorders.

Transcriptome Analysis of the Responses of Rice Leaves to Chilling and Subsequent Recovery

Improving chilling tolerance at the seedling stage in rice is essential for agricultural research. We combined a physiological analysis with transcriptomics in a variety Dular subjected to chilling followed by recovery at normal temperature to better understand the chilling tolerance mechanisms of rice. Chilling inhibited the synthesis of chlorophyll and non-structural carbohydrate (NSC) and disrupted the ion balance of the plant, resulting in the impaired function of rice leaves. The recovery treatment can effectively reverse the chilling-related injury. Transcriptome results displayed that 21,970 genes were identified at three different temperatures, and 11,732 genes were differentially expressed. According to KEGG analysis, functional categories for differentially expressed genes (DEGs) mainly included ribosome (8.72%), photosynthesis–antenna proteins (7.38%), phenylpropanoid biosynthesis (11.41%), and linoleic acid metabolism (10.07%). The subcellular localization demonstrated that most proteins were located in the chloroplasts (29.30%), cytosol (10.19%), and nucleus (10.19%). We proposed that some genes involved in photosynthesis, ribosome, phenylpropanoid biosynthesis, and linoleic acid metabolism may play key roles in enhancing rice adaptation to chilling stress and their recovery capacity. These findings provide a foundation for future research into rice chilling tolerance mechanisms.

Recent advances in biological properties of brown algae-derived compounds for nutraceutical applications

The increasing demand for nutraceuticals in the circular economy era has driven the research toward studying bioactive compounds from renewable underexploited resources. In this regard, the exploration of brown algae has shown significant growth and maintains a great promise for the future. One possible explanation could be that brown algae are rich sources of nutritional compounds (polyunsaturated fatty acids, fiber, proteins, minerals, and vitamins) and unique metabolic compounds (phlorotannins, fucoxanthin, fucoidan) with promising biological activities that make them good candidates for nutraceutical applications with increased value-added. In this review, a deep description of bioactive compounds from brown algae is presented. In addition, recent advances in biological activities ascribed to these compounds through in vitro and in vivo assays are pointed out. Delivery strategies to overcome some drawbacks related to the direct application of algae-derived compounds (low solubility, thermal instability, bioavailability, unpleasant organoleptic properties) are also reviewed. Finally, current commercial and legal statuses of ingredients from brown algae are presented, considering future therapeutical and market perspectives as nutraceuticals.

Natural Products from Plants and Algae for Treatment of Alzheimer’s Disease: A Review

Neurodegenerative disorders including Parkinson’s disease (PD), Huntington’s disease (HD) and the most frequent, Alzheimer’s disease (AD), represent one of the most urgent medical needs worldwide. Despite a significantly developed understanding of disease development and pathology, treatments that stop AD progression are not yet available. The recent approval of sodium oligomannate (GV-971) for AD treatment in China emphasized the potential value of natural products for the treatment of neurodegenerative disorders. Many current clinical studies include the administration of a natural compound as a single and combination treatment. The most prominent mechanisms of action are anti-inflammatory and anti-oxidative activities, thus preserving cellular survival. Here, we review current natural products that are either approved or are in testing for a treatment of neurodegeneration in AD. In addition to the most important compounds of plant origin, we also put special emphasis on compounds from algae, given their neuroprotective activity and their underlying mechanisms of neuroprotection.

An Overview of Potential Seaweed-Derived Bioactive Compounds for Pharmaceutical Applications

Nowadays, seaweeds are widely involved in biotechnological applications. Due to the variety of bioactive compounds in their composition, species of phylum Ochrophyta, class Phaeophyceae, phylum Rhodophyta and Chlorophyta are valuable for the food, cosmetic, pharmaceutical and nutraceutical industries. Seaweeds have been consumed as whole food since ancient times and used to treat several diseases, even though the mechanisms of action were unknown. During the last decades, research has demonstrated that those unique compounds express beneficial properties for human health. Each compound has peculiar properties (e.g., antioxidant, antimicrobial, antiviral activities, etc.) that can be exploited to enhance human health. Seaweed’s extracted polysaccharides are already involved in the pharmaceutical industry, with the aim of replacing synthetic compounds with components of natural origin. This review aims at a better understanding of the recent uses of algae in drug development, with the scope of replacing synthetic compounds and the multiple biotechnological applications that make up seaweed’s potential in industrial companies. Further research is needed to better understand the mechanisms of action of seaweed’s compounds and to embrace the use of seaweeds in pharmaceutical companies and other applications, with the final scope being to produce sustainable and healthier products.

Phlorotannins-bioactivity and extraction perspectives

Phlorotannins, a seaweed based class of polyphenolic compounds, have proven to possess potential bioactivities such as antioxidant, antimicrobial, anti-allergic, anti-diabetic, anti-inflammatory, anti-cancerous, neuroprotection etc. These bioactivities have further increased demand globally and sustainable techniques such as supercritical fluid extraction, microwave assisted extraction, enzyme assisted extraction, extraction using deep eutectic solvents etc. are being explored currently for production of phlorotannin-rich extracts. In spite of such well documented bioactivities, very few phlorotannin-based nutraceuticals are available commercially which highlights the significance of generating consumer awareness about their physiological benefits. However, for industry level commercialization accurate quantification of phlorotannins with respect to the different classes is vital requiring sophisticated analytical techniques such as mass spectrometry, ¹H-NMR spectroscopy etc. owing to the wide structural diversity. This review summarizes the extraction and bioactivities of phlorotannins based on the findings of in vivo and in vitro studies.

Influence of Gender and Age of Brown Seaweed (Fucus vesiculosus) on Biochemical Activities of Its Aqueous Extracts

Fucus vesiculosus L. is a common coastal brown seaweed associated with various benefits to human health due to its phenolic content and nutrients and is used as food through different methods of consumption. This study aims to evaluate the influence of the seaweed’s gender and growth stage on different types of biological activities as well as its chemical constitution and elements present. Akin to food preparation, aqueous extracts of the seaweed were prepared at 25 °C (salad) and 100 °C (soup). Biological activities were determined by measuring total phenol content (TPC), antioxidant activity and inhibition of acetylcholinesterase (AChE). Liquid Chromatography High Resolution Mass Spectrometry (LC-HRMS/MS) was used for compound identification, and elemental analysis was carried out by using Total Reflection X-ray Fluorescence Spectrometry (TXRF). Older females and males had higher TPC compared to the new ones at 100 °C. Antioxidant activity depended on the extraction temperature but was higher for the youngest male at 100 °C. AChE inhibitory activity was higher for older males at 25 °C, but at 100 °C it was higher for older females. Primary metabolites and various phloroglucinol were the main compounds identified. Additionally, since this seaweed is often harvested in estuarine systems with high anthropogenic impacts, its safety was evaluated through the evaluation of the sample’s metal content. The heavy metals detected are within the limits established by various regulating entities, pointing to a safe food source.

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.

Marine-Derived Compounds with Anti-Alzheimer's Disease Activities

Alzheimer’s disease (AD) is an irreversible and progressive brain disorder that slowly destroys memory and thinking skills, and, eventually, the ability to perform simple tasks. As the aging population continues to increase exponentially, AD has become a big concern for society. Therefore, neuroprotective compounds are in the spotlight, as a means to tackle this problem. On the other hand, since it is believed—in many cultures—that marine organisms in an individual diet cannot only improve brain functioning, but also slow down its dysfunction, many researchers have focused on identifying neuroprotective compounds from marine resources. The fact that the marine environment is a rich source of structurally unique and biologically and pharmacologically active compounds, with unprecedented mechanisms of action, marine macroorganisms, such as tunicates, corals, sponges, algae, as well as microorganisms, such as marine-derived bacteria, actinomycetes, and fungi, have been the target sources of these compounds. Therefore, this literature review summarizes and categorizes various classes of marine-derived compounds that are able to inhibit key enzymes involved in AD, including acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), β-secretase (BACE-1), and different kinases, together with the related pathways involved in the pathogenesis of AD. The compounds discussed herein are emerging as promising anti-AD activities for further in-depth in vitro and in vivo investigations, to gain more insight of their mechanisms of action and for the development of potential anti-AD drug leads.

The State of The Art on Acetylcholinesterase Inhibitors in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a chronic disabling disease that affects the central nervous system. The main consequences of AD include the decline of cognitive functions and language disorders. One of the causes leading to AD is the decrease of neurotransmitter acetylcholine (ACh) levels in the brain, in part due to a higher activity of acetylcholinesterase (AChE), the enzyme responsible for its degradation. Many acetylcholinesterase inhibitors (AChEIs), both natural and synthetic, have been developed and used through the years to counteract the progression of the disease. The first of such drugs approved for a therapeutic use was tacrine, that binds through a reversible bond to the enzyme. However, tacrine has since been withdrawn because of its adverse effects. Currently, donepezil and galantamine are very promising AChEIs with clinical benefits. Moreover, rivastigmine is considered a pseudo-irreversible compound with anti-AChE action, providing similar effects at the clinical level. The purpose of this review is to provide an overview of what has been published over the last decade on the effectiveness of AChEIs in AD, analysing the most relevant issues under the clinical and methodological profiles and the consequent possible welfare effects for the whole world. Furthermore, novel drugs and possible therapeutic approaches are also discussed.

Functional foods and bioactive ingredients harnessed from the ocean: current status and future perspectives

With an increase in life expectancy and decrease of quality-of-life couple with the high prevalence of diseases, diet is expected to play a key function in sustaining human health. Nutritionists, food technologists and medical experts are working in synergy to cater for the increasing demand of food with associated therapeutic benefits, commonly known as functional food, that may improve well-being and reduce the risk of diseases. Interestingly, the marine ecosystem, due to its abundant and phenomenal biodiversity of marine organisms, constitutes a vital source of a panoply of healthy foods supply for the thriving functional food industry. Marine organisms such as seaweeds, sea cucumbers, sponges, and mollusks amongst others are sources of thousands of biologically active metabolites with antioxidant, anti-parasitic, antiviral, anti-inflammatory and anticancer properties. Given the growing number of research and interest to probe into the therapeutic roles of marine products, this review was designed to provide a comprehensive summary of the therapeutic properties of marine organisms (macroalgae, sea cucumbers and fish among others) which are consumed worldwide, in addition to their potentials and as sources of functional ingredients for developing novel food and fostering wellness. The gap between research development and actual commercialization, and future prospects of marine-based products also summarized to some extent.

The Seaweed Diet in Prevention and Treatment of the Neurodegenerative Diseases

Edible marine algae are rich in bioactive compounds and are, therefore, a source of bioavailable proteins, long chain polysaccharides that behave as low-calorie soluble fibers, metabolically necessary minerals, vitamins, polyunsaturated fatty acids, and antioxidants. Marine algae were used primarily as gelling agents and thickeners (phycocolloids) in food and pharmaceutical industries in the last century, but recent research has revealed their potential as a source of useful compounds for the pharmaceutical, medical, and cosmetic industries. The green, red, and brown algae have been shown to have useful therapeutic properties in the prevention and treatment of neurodegenerative diseases: Parkinson, Alzheimer’s, and Multiple Sclerosis, and other chronic diseases. In this review are listed and described the main components of a suitable diet for patients with these diseases. In addition, compounds derived from macroalgae and their neurophysiological activities are described.

Antioxidant activity and laxative effects of tannin-enriched extract of Ecklonia cava in loperamide-induced constipation of SD rats

To investigate the role of tannin-enriched extracts of Ecklonia cava (TEE) on the regulation of oxidative balance and laxative activity in chronic constipation, we investigated alterations after exposure to TEE, on constipation phenotypes, muscarinic cholinergic regulation, and oxidative stress responses in the transverse colons of SD rats with loperamide (Lop)-induced constipation. This extract contains high levels of total condensed tannin content (326.5 mg/g), and exhibited high inhibitory activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. TEE treatment induced significant improvements in reactive oxygen species (ROS) production, superoxide dismutase (SOD) expression and nuclear factor erythroid 2-related factor 2 (Nrf2) phosphorylation in primary smooth muscles of rat intestine cells (pRISMCs) and transverse colon of constipation model. Also, Lop+TEE treated groups showed alleviated outcomes for the following: most stool parameters, gastrointestinal transit, and intestine length were remarkably recovered; a similar recovery pattern was observed in the histopathological structure, mucin secretion, water channel expression and gastrointestinal hormones secretion in the transverse colon; expressions of muscarinic acetylcholine receptors M2/M3 (mAChR M2/M3) and their mediators on muscarinic cholinergic regulation were significantly recovered. Taken together, these results provide the first evidence that TEE stimulates oxidative stress modulation and muscarinic cholinergic regulation when exerting its laxative effects in chronic constipation models.

Polyphenols from Brown Seaweeds (Ochrophyta, Phaeophyceae): Phlorotannins in the Pursuit of Natural Alternatives to Tackle Neurodegeneration

Globally, the burden of neurodegenerative disorders continues to rise, and their multifactorial etiology has been regarded as among the most challenging medical issues. Bioprospecting for seaweed-derived multimodal acting products has earned increasing attention in the fight against neurodegenerative conditions. Phlorotannins (phloroglucinol-based polyphenols exclusively produced by brown seaweeds) are amongst the most promising nature-sourced compounds in terms of functionality, and though research on their neuroprotective properties is still in its infancy, phlorotannins have been found to modulate intricate events within the neuronal network. This review comprehensively covers the available literature on the neuroprotective potential of both isolated phlorotannins and phlorotannin-rich extracts/fractions, highlighting the main key findings and pointing to some potential directions for neuro research ramp-up processes on these marine-derived products.

In vitro multifunctionality of phlorotannin extracts from edible Fucus species on targets underpinning neurodegeneration

Bioprospecting for seaweed-derived multimodal acting products have earned increasing attention in the fight against diseases of multifactorial origin, such as neurodegenerative conditions. This is a pioneer study on the in vitro screening of neuroactive properties of phlorotannin-targeted extracts from edible Fucus species. Phlorotannin extracts exhibited multifunctional antioxidant properties, which were suggested to be responsible for counteracting glutamate toxicity in neuronal human-derived SH-SY5Y cells. They also inhibited the activity of enzymes (cholinesterases, monoaminoxidases A and B, and tyrosinase) linked to a set of events that contribute to the onset/progression of neurodegeneration. In general, the bioactivities were correlated with the total phlorotannin content and phloroglucinol tetramers were suggested to be behind the observed effects. The capacity of the phlorotannin extracts to interact with multiple in vitro targets underpinning neurodegeneration points to the potential interest of the selected seaweed species for development of new added-value products and promising neuroactive agents.

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.

Pharmacological and Cosmeceutical Potential of Seaweed Beach-Casts of Macaronesia

Seaweed beach-casts are a seasonal phenomenon that regularly deposits tons of algae biomass on beaches, which are usually disposed of in landfills. The present work aimed to contribute to the valorization of this biomass by studying bioactivities that reveal its potential in the pharmaceutical and/or cosmeceutical industries. Methanol and ethanol extracts and fractions from 15 beach-casts biomass were tested for a range of bioactivities. Eight of the most active samples exhibit IC50 values between 11.38 µg/mL and 19.28 µg/mL and selectivity indexes higher than 3.8, against NCI-H1299 (lung cancer) and T47D (breast cancer). Concerning antiaging potential, all the extracts tested presented UV protection, with SPF values above 30, like the standard sunscreen. Regarding aging-related enzymes, 24 samples were tyrosinase inhibitors exhibiting IC50 values from 9.01 µg/mL to 200.09 µg/mL. Eight extracts inhibited collagenase (IC50 < 248.76 µg/mL), two of them more actively than positive control EDTA (IC50 = 59.26 µg/mL). In addition to UV protection, the cumulative effect of antityrosinase and anticollagenase activities shown by the samples suggest that they may play a significant role in preventing skin photoaging. The results obtained demonstrate the high potential of beach-cast seaweed biomass as sources of cosmetic bioproducts with antiaging effects, and of selective cytotoxic metabolites.

Editan (Lasianthera africana) leaf-inclusive diets modulate some neuronal enzyme activities and antioxidant status of cyclophosphamide-treated Wistar rats

The effect of Editan (Lasianthera africana) leaf inclusive diet (ELD) on neuronal cholinesterases (ChE), ecto-5'-nucleotidase, and endogenous antioxidant indices [superoxide dismutase (SOD), catalase (CAT), glutathione (GSH)] in cyclophosphamide (CYP)-administered albino rats were investigated. Thirty male albino Wistar rats were dissevered appropriately (n = 6). Group I-normal control rats (NC), II-untreated CYP-administered rats, III-CYP-administered rats pre-treated with donepezil (DON), group IV-CYP-administered rats fed ELD, and V-normal rats fed with ELD for 21 days. Results obtained revealed that CYP-administered rats significantly (p < .05) had elevated activities of ChE, ecto-5'-nucleotidase and thiobarbituric acid reactive species (TBARS), and concomitantly decreased in the antioxidant indices. However, pre-treatment with either DON or ELD reversed these effects, thereby eliciting a therapeutic effect which could be linked to the rich polyphenol and alkaloid constituents in the studied leaf, and could be responsible for the potential ethnopharmacological actions of the ELD in the management neurodegeneration. PRACTICAL APPLICATIONS: Currently, the use of plant-food to control diseased conditions due to their phytochemicals has been explored, most especially, the indigenous edible vegetables from the Southwestern part of Nigeria. "Editan" leafy vegetable scientifically known as Lasianthera africana is commonly used in soups preparation and in folklore for the management of some human ailments. Editan leaf is a rich source of alkaloid and phenolic compounds, which could be used to treat and or manage neurological diseases. This study, therefore, unravels the fact that the studied leafy vegetable possesses therapeutic potentials toward the management of neurological disorders.

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

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

Bioactive compounds in seaweeds: An overview of their biological properties and safety

Seaweeds are among the significant currently exploited marine plant resources which are gaining full applications in culinary, cosmetic, pharmaceutical, and biotechnological processes. Much attention has been devoted to seaweeds based on their proven health benefits and is considered as a rich source of structurally different bioactive metabolites for the discovery of novel functional food-based pharmacophores/drugs. Nonetheless, there is still a dearth of updated compilation and analysis of the in-depth pharmacological activities of these compounds. This review, therefore, aims to provide a piece of up-to-date detailed information on the major compounds isolated from various seaweed species together with their in-vitro and in-vivo biological properties. These compounds were found to possess broad pharmacological properties and inhibitory enzyme activities against critical enzymes involved in the aetiology of noncommunicable diseases. However, their toxicity, clinical efficacy, mechanisms of action, and interaction with conventional foods, are still less explored and require more attention in future studies.

An in vivo anti-tumor effect of eckol from marine brown algae by improving the immune response

The anti-cancer activities of brown algae and some active extracts or components from brown algae have been demonstrated. But the anti-tumor activities of eckol, a new natural phlorotannin derived from marine brown algae, are poorly understood. In order to investigate the in vivo anti-tumor effect and its potential mechanisms of eckol in a sarcoma 180 (S180) xenograft-bearing animal model, S180 xenograft-bearing mice were randomly divided into 4 groups: model control, and eckol low-dose (0.25 mg kg-1), middle-dose (0.5 mg kg-1) and high-dose (1.0 mg kg-1) groups. After eckol administration, the tumor inhibition, tumor tissue histology, thymus index and spleen index were measured. The apoptotic tumor cells were detected using the terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) assay. The protein expression levels of cleaved Caspase-3 and Caspase-9 (two key apoptotic proteins), Bcl-2 and Bax (two key anti-apoptosis-related genes), as well as epidermal growth factor receptor (EGFR, a well-known cell proliferation-stimulating molecule in tumorigenesis) and p-EGFR in tumor tissues were determined by western blot. A carbon particle clearance test, measurement of serum cytokine levels, a splenic T lymphocyte proliferation test, and T lymphocyte subpopulation analysis were used to evaluate the effect of eckol on the immune function of tumor-bearing mice. Moreover, CD11c+-dendritic cell (DC) infiltration in tumor tissues was detected by immunohistochemistry, and the surface molecules on bone marrow-derived DCs were analyzed using flow cytometry. The pro-apoptosis and anti-proliferation activities of eckol were manifested by the increased TUNEL-positive apoptotic cells, the upregulated Caspase-3 and Caspase-9 expression, and the downregulated expression of Bcl-2, Bax, EGFR and p-EGFR in eckol-treated transplanted S180 tumors. Most importantly, eckol stimulated the mononuclear phagocytic system, recruited and activated DCs, promoted the tumor-specific Th1 responses, increased the CD4+/CD8+ T lymphocyte ratio, and enhanced cytotoxic T lymphocyte responses in the eckol-treated animals, suggesting its potent stimulatory property on innate and adaptive immune responses. This study suggested that eckol might act as a functional food constituent derived from marine brown algae with a potential in vivo anti-tumor effect achieved by improving the immune response.

Characterizing Eckol as a Therapeutic Aid: A Systematic Review

The marine biosphere is a treasure trove of natural bioactive secondary metabolites and the richest source of structurally diverse and unique compounds, such as phlorotannins and halo-compounds, with high therapeutic potential. Eckol is a precursor compound representing the dibenzo-1,4-dioxin class of phlorotannins abundant in the Ecklonia species, which are marine brown algae having a ubiquitous distribution. In search of compounds having biological activity from macro algae during the past three decades, this particular compound has attracted massive attention for its multiple therapeutic properties and health benefits. Although several varieties of marine algae, seaweed, and phlorotannins have already been well scrutinized, eckol deserves a place of its own because of the therapeutic properties it possesses. The relevant information about this particular compound has not yet been collected in one place; therefore, this review focuses on its biological applications, including its potential health benefits and possible applications to restrain diseases leading to good health. The facts compiled in this review could contribute to novel insights into the functions of eckol and potentially enable its use in different uninvestigated fields.

Isolation and Purification of a Neuroprotective Phlorotannin from the Marine Algae Ecklonia maxima by Size Exclusion and High-Speed Counter-Current Chromatography

Phlorotannins are polyphenolic metabolites of marine brown algae that have been shown to possess health-beneficial biological activities. An efficient approach using a combination of high-speed counter-current chromatography (HSCCC) and size exclusion chromatography with a Sephadex LH-20 has been successfully developed for the isolation and purification of a neuroprotective phlorotannin, eckmaxol, from leaves of the marine brown algae, Ecklonia maxima. The phlorotannin of interest, eckmaxol, was isolated with purity >95% by HSCCC using an optimized solvent system composed of n-hexane-ethyl acetate-methanol-water (2:8:3:7, v/v/v/v) after Sephadex LH-20 size exclusion chromatography. This compound was successfully purified in the quantity of 5.2 mg from 0.3 kg of the E. maxima crude organic extract. The structure of eckmaxol was identified and assigned by NMR spectroscopic and mass spectrometric analyses. The purification method developed for eckmaxol will facilitate the further investigation and development of this neuroprotective agent as a drug lead or pharmacological probe. Furthermore, it is suggested that the combination of HSCCC and size exclusion chromatography could be more widely applied for the isolation and purification of phlorotannins from marine algae.

Natural cholinesterase inhibitors from marine organisms

Covering: Published between 1974 up to 2018Inhibition of cholinesterases is a common approach for the management of several disease states. Most notably, cholinesterase inhibitors are used to alleviate the symptoms of neurological disorders like dementia and Alzheimer's disease and treat myasthenia gravis and glaucoma. Historically, most drugs of natural origin have been isolated from terrestrial sources and inhibitors of cholinesterases are no exception. However, the last 50 years have seen a rise in the quantity of marine natural products with close to 25 000 reported in the scientific literature. A number of marine natural products with potent cholinesterase inhibitory properties have also been reported; isolated from a variety of marine sources from algae to ascidians. Representing a diverse range of structural classes, these compounds provide inspirational leads that could aid the development of therapeutics. The current paper aims to, for the first time, comprehensively summarize the literature pertaining to cholinesterase inhibitors derived from marine sources, including the first papers published in 1974 up to 2018. The review does not report bioactive extracts, only isolated compounds, and a specific focus lies on compounds with reported dose-response data. In vivo and mechanistic data is included for compounds where this is reported. In total 185 marine cholinesterase inhibitors and selected analogs have been identified and reported and some of the compounds display inhibitory activities comparable or superior to cholinesterase inhibitors in clinical use.

Bioactive molecules derived from smoke and seaweed Ecklonia maxima showing phytohormone-like activity in Spinacia oleracea L

Bioactive compounds such as karrikinolide (KAR1 from smoke) and eckol (from the seaweed Ecklonia maxima) show promising effects on several important crop plants. These plant growth-stimulating organic biomolecules, along with crude extracts (smoke-water and Kelpak® product prepared from Ecklonia maxima), were tested on spinach plants. Eckol sprayed at 10-6 M significantly increased all the growth and biochemical parameters examined compared to control spinach plants. All tested plant growth biostimulants significantly increased total chlorophyll, carotenoids and protein content of spinach leaves. The cytokinin profile of spinach plants was also determined. Cis-zeatin, dihydrozeatin and isopentenyladenine types of cytokinins were promoted by both smoke- and seaweed-based biostimulants. In comparison to the control plants, the level of free sinapic acid was greater in all spinach plants treated with these biostimulants. The application of these biostimulants can help spinach crop by improving growth, yield and nutritional quality; moreover, they are organic and cost-effective.

Influence of biostimulants-seed-priming on Ceratotheca triloba germination and seedling growth under low temperatures, low osmotic potential and salinity stress

Extreme temperatures, drought and salinity stress adversely affect seed germination and seedling growth in crop species. Seed priming has been recognized as an indispensable technique in the production of stress-tolerant plants. Seed priming increases seed water content, improves protein synthesis using mRNA and DNA and repair mitochondria in seeds prior to germination. The current study aimed to determine the role of biostimulants-seed-priming during germination and seedling growth of Ceratotheca triloba (Bernh.) Hook.f. (an indigenous African leafy vegetable) under low temperature, low osmotic potential and salinity stress conditions. Ceratotheca triloba seeds were primed with biostimulants [smoke-water (SW), synthesized smoke-compound karrikinolide (KAR₁), Kelpak^® (commercial seaweed extract), phloroglucinol (PG) and distilled water (control)] for 48h at 25°C. Thereafter, primed seeds were germinated at low temperatures, low osmotic potential and high NaCl concentrations. Low temperature (10°C) completely inhibited seed germination. However, temperature shift to 15°C improved germination. Smoke-water and KAR₁ enhanced seed germination with SW improving seedling growth under different stress conditions. Furthermore, priming seeds with Kelpak^® stimulated percentage germination, while PG and the control treatment improved seedling growth at different PEG and NaCl concentrations. Generally, high concentrations of PEG and NaCl brought about detrimental effects on seed germination and seedling growth. Findings from this study show the potential role of seed priming with biostimulants in the alleviation of abiotic stress conditions during seed germination and seedling growth in C. triloba plants.

Phenolic compounds from three brown seaweed species using LC-DAD-ESI-MS/MS

The phenolic compounds of extracts from Ascophyllum nodosum (ANE), Bifurcaria bifurcata (BBE) and Fucus vesiculosus (FVE) from Galicia (NW Spain) were analyzed by liquid chromatography-diode array detection coupled to negative electrospray ionization-tandem mass spectrometry (LC-DAD-ESI-MS/MS) with the interest to evaluate their potential application as functional ingredients. Phlorotannins were tentatively identified as the main phenolic compounds in the three extracts, followed by phenolic acids, and flavonoids. Fuhalols were present in ANE and BBE, while hydroxyfuhalols were identified in BBE and FVE. Eckol derivatives were present in the three extracts. Quinic acid derivatives were tentatively identified in the three seaweed species; in addition, ANE showed specifically hydroxybenzoic and rosmarinic acid derivatives, BBE showed rosmarinic acid, and FVE contained p-coumaric and ferulic acid derivatives. Regarding flavonoids, acacetin derivatives were tentatively identified in the three extracts, hispidulin and a gallocatechin derivative were specifically detected in ANE, and cypellocarpin C was present in BBE. In conclusion, all brown seaweed extracts studied could be exploited as sources of antioxidant phenolic compounds with potential applications in the food and health sectors.

Recent advances in pharmacological research on Ecklonia species: a review

The genus Ecklonia (Lessoniaceae, Phaeophyceae), commonly called kelp (brown algae), is abundant on the coasts of Japan and Korea. During the past few decades, Ecklonia species have received tremendous attention for their wide range of therapeutic properties and multiple health benefits, such as great nutritional value and being rich in vitamins, minerals, dietary fiber, proteins, and polysaccharides. Several novel functional ingredients with diversified biological activities have been isolated and possess antimicrobial, antiviral, hepatoprotective, cardioprotective, anti-inflammatory, neuroprotective, anticarcinogenic, immunomodulatory, hypolipidemic, anti-diabetic, and antioxidant therapeutic properties. The present review discusses the phytochemical, pharmacological, therapeutic, nutritional, and health benefits of different species of genus Ecklonia, as well as their use in the prevention of disease and maintenance of good health.

Enhancing growth, phytochemical constituents and aphid resistance capacity in cabbage with foliar application of eckol--a biologically active phenolic molecule from brown seaweed

Although foliar application of seaweed extracts on plant growth and development has and is extensively studied, reliable knowledge and understanding of the mode of action of particular compound(s) responsible for enhancing plant growth is lacking. A brown seaweed Ecklonia maxima is widely used commercially as a biostimulant to improve plant growth and crop protection. Eckol, a phenolic compound isolated from E. maxima has recently shown stimulatory effects in maize, indicating its potential use as a plant biostimulant. Cabbage is a widely cultivated vegetable crop throughout the world, which requires high input of fertilizers and is susceptible to several aphid borne diseases. This study was conducted to evaluate the effect of foliar application of eckol on the growth, phytochemical constituents and myrosinase activity (aphid resistance capacity) of commercially cultivated cabbage. Foliar application of eckol (10(-6) M) significantly enhanced shoot and root length, shoot and root fresh and dry weight, leaf area and leaf number. This treatment also showed a significant increase in photosynthetic pigments (chlorophyll 'a', chlorophyll 'b', total chlorophyll and carotenoid) compared to the untreated plants. The levels of protein, proline and iridoid glycosides were significantly higher in cabbage leaves with eckol treatment. All the control plants were severely infested with cabbage aphid (Brevicoryne brassicae) but no infestation was observed on the eckol-sprayed plants, which can be attributed to an increase in myrosinase activity. This study reveals dual effects (plant growth promoting and insect repelling) of eckol on cabbage plants that need further investigations both under field conditions and in other brassicaceous species.

Discovery of Some Piperine-Based Phenylsulfonylhydrazone Derivatives as Potent Botanically Narcotic Agents

By structural modification of piperine, some piperine-based phenylsulfonylhydrazone derivatives exhibited an unprecedented and potent narcotic activity against the oriental armyworm, Mythimna separata (Walker). The ND50 values of compounds 6c and 6e against the third-instar larvae of M. separata, which were more potent than those of wilfortrine and wilforgine, were 0.0074 μmol (after 3.5 h), and 0.0075 μmol (after 7 h) per larvae, respectively. By transmission electron microscope, it demonstrated that mitochondria were vacuolated and swollen in the ganglion cell of M. separata after treatment with 6c. More importantly, 6c selectively displayed the inhibition activity on acetylcholine esterase (AchE) of M. separata. This work paved the way for further studying the insecticidal mechanism of 6c as a new and promising botanical narcotic agent.

Physiological role of phenolic biostimulants isolated from brown seaweed Ecklonia maxima on plant growth and development

MAIN CONCLUSION

Eckol, a major phenolic compound isolated from brown seaweed significantly enhanced the bulb size and bioactive compounds in greenhouse-grown Eucomis autumnalis. We investigated the effect of eckol and phloroglucinol (PG) (phenolic compounds) isolated from the brown seaweed, Ecklonia maxima (Osbeck) Papenfuss on the growth, phytochemical and auxin content in Eucomis autumnalis (Mill.) Chitt. The model plant is a popular medicinal species with increasing conservation concern. Eckol and PG were tested at 10(-5), 10(-6) and 10(-7) M using soil drench applications. After 4 months, growth parameters, phytochemical and auxin content were recorded. When compared to the control, eckol (10(-6) M) significantly improved bulb size, fresh weight and root production while the application of PG (10(-6) M) significantly increased the bulb numbers. However, both compounds had no significant stimulatory effect on aerial organs. Bioactive phytochemicals such as p-hydroxybenzoic and ferulic acids were significantly increased in eckol (10(-5) M) and PG (10(-6) M) treatments, compared to the control. Aerial (1,357 pmol/g DW) and underground (1,474 pmol/g DW) parts of eckol-treated (10(-5) M) plants yielded the highest concentration of indole-3-acetic acid. Overall, eckol and PG elicited a significant influence on the growth and physiological response in E. autumnalis. Considering the medicinal importance of E. autumnalis and the increasing strains on its wild populations, these compounds are potential tools to enhance their cultivation and growth.

Characterization of Phlorotannins from Brown Algae by LC-HRMS

Phlorotannins are a class of polyphenols found in brown seaweeds that have significant potential for use as therapeutics, owing to their wide range of bioactivities. Molecular characterization of phlorotannin-enriched extracts is challenging due to the extreme sample complexity and the wide range of molecular weights observed. Herein, we describe a method for characterizing phlorotannins employing ultrahigh-pressure liquid chromatography (UHPLC) operating in hydrophilic interaction liquid chromatography (HILIC) mode combined with high-resolution mass spectrometry (HRMS).

Advances in algal drug research with emphasis on enzyme inhibitors

Enzyme inhibitors are now included in all kinds of drugs essential to treat most of the human diseases including communicable, metabolic, cardiovascular, neurological diseases and cancer. Numerous marine algae have been reported to be a potential source of novel enzyme inhibitors with various pharmaceutical values. Thus, the purpose of this review is to brief the enzyme inhibitors from marine algae of therapeutic potential to treat common diseases. As per our knowledge this is the first review for the potential enzyme inhibitors from marine origin. This review contains 86 algal enzyme inhibitors reported during 1989-2013 and commercial enzyme inhibitors available in the market. Compounds in the review are grouped according to the disease conditions in which they are involved; diabetes, obesity, dementia, inflammation, melanogenesis, AIDS, hypertension and other viral diseases. The structure-activity relationship of most of the compounds are also discussed. In addition, the drug likeness properties of algal inhibitors were evaluated using Lipinski's 'Rule of Five'.

Bioactive compounds from macroalgae in the new millennium: implications for neurodegenerative diseases

Marine environment has proven to be a rich source of structurally diverse and complex compounds exhibiting numerous interesting biological effects. Macroalgae are currently being explored as novel and sustainable sources of bioactive compounds for both pharmaceutical and nutraceutical applications. Given the increasing prevalence of different forms of dementia, researchers have been focusing their attention on the discovery and development of new compounds from macroalgae for potential application in neuroprotection. Neuroprotection involves multiple and complex mechanisms, which are deeply related. Therefore, compounds exerting neuroprotective effects through different pathways could present viable approaches in the management of neurodegenerative diseases, such as Alzheimer's and Parkinson's. In fact, several studies had already provided promising insights into the neuroprotective effects of a series of compounds isolated from different macroalgae species. This review will focus on compounds from macroalgae that exhibit neuroprotective effects and their potential application to treat and/or prevent neurodegenerative diseases.

Potential antiradical and alpha-glucosidase inhibitors from Ecklonia maxima (Osbeck) Papenfuss

Alpha-glucosidase inhibitors play a potential role in the treatment of type 2 diabetes by delaying glucose absorption in the small intestine. Ecklonia maxima, a brown alga which grows abundantly on the west coast of South Africa, is used to produce alginate, animal feed, nutritional supplements and fertilizer. The crude aqueous methanol extract, four solvent fractions and three phlorotannins: 1,3,5-trihydroxybenezene (phloroglucinol) (1), dibenzo [1,4] dioxine-2,4,7,9-tetraol (2) and hexahydroxyphenoxydibenzo [1,4] dioxine (eckol) (3) isolated from E. maxima were evaluated for antiradical and alpha-glucosidase inhibitory activities. All the phlorotannins tested had strong antioxidant activities on DPPH free radicals with EC50 values ranging from 0.008 to 0.128μM. Compounds 2 and 3 demonstrated stronger antioxidant activity and an alpha-glucosidase inhibitory property than positive controls. These results suggest that E. maxima could be a natural source of potent antioxidants and alpha-glucosidase inhibitors. This study could facilitate effective utilization of E. maxima as an oral antidiabetic drug or functional food ingredient with a promising role in the formulation of medicines and nutrition supplements.