Depressive effects on the central nervous system and underlying mechanism of the enzymatic extract and its phlorotannin-rich fraction from Ecklonia cava edible brown seaweed

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 Polyphenol Phlorotannins as a Natural Sleep Aid for Treatment of Insomnia: A Review of Sedative-Hypnotic Effects and Mechanism of Action

Insomnia is a common sleep disorder. Natural sleep aids are gaining worldwide popularity as alternatives to prescription drugs for improving sleep. Recently, numerous studies have investigated the sedative-hypnotic effects of the polyphenols of terrestrial plants. The hypnotic effects of marine polyphenols have also been studied in recent years. Phlorotannins are marine polyphenols that are found only in brown algae. Phlorotannins exert sedative-hypnotic effects via the gamma-aminobutyric acid type A-benzodiazepine receptor. In addition, the brown seaweed Ecklonia cava supplement containing phlorotannins has been approved by the Ministry of Food and Drug Safety as a health-functional ingredient that helps improve sleep quality. Currently, it is meaningful to deal with the sedative-hypnotic effects of phlorotannins as natural sleep aids. The current review comprehensively presents the sedative-hypnotic effects in animal models and human clinical trials as well as their mechanism of action, extraction, purification, and safety.

Phenolics as GABAA Receptor Ligands: An Updated Review

Natural products can act as potential GABA modulators, avoiding the undesirable effects of traditional pharmacology used for the inhibition of the central nervous system such as benzodiazepines (BZD). Phenolics, especially flavonoids and phlorotannins, have been considered as modulators of the BZD-site of GABA_A receptors (GABA_ARs), with sedative, anxiolytic or anticonvulsant effects. However, the wide chemical structural variability of flavonoids shows their potential action at more than one additional binding site on GABA_ARs, which may act either negatively, positively, by neutralizing GABA_ARs, or directly as allosteric agonists. Therefore, the aim of the present review is to compile and discuss an update of the role of phenolics, namely as pharmacological targets involving dysfunctions of the GABA system, analyzing both their different compounds and their mechanism as GABAergic modulators. We focus this review on articles written in English since the year 2010 until the present. Of course, although more research would be necessary to fully establish the type specificity of phenolics and their pharmacological activity, the evidence supports their potential as GABA_AR modulators, thereby favoring their inclusion in the development of new therapeutic targets based on natural products. Specifically, the data compiled in this review allows for the directing of future research towards ortho-dihydroxy diterpene galdosol, the flavonoids isoliquiritigenin (chalcone), rhusflavone and agathisflavone (biflavonoids), as well as the phlorotannins, dieckol and triphlorethol A. Clinically, flavonoids are the most interesting phenolics due to their potential as anticonvulsant and anxiolytic drugs, and phlorotannins are also of interest as sedative agents.

Dieckol: a brown algal phlorotannin with biological potential

Dieckol [C36H22O18], is a naturally occurring phlorotannin found in some brown algal species. Dieckol is gaining more attention in the scientific community for its potential biological activities. It has been exhibited a broad spectrum of therapeutic functions including anti-bacterial, anti-cancer, anti-oxidant, anti-aging, anti-diabetic, neuroprotective, and other medicinal applications. Distinct emphasis has been given to extraction, purification, and biomedical applications of dieckol. This critical review comprises of in vitro, in vivo, and in silico biological properties of dieckol. An attempt has been made to evaluate the effectiveness, therapeutical application, and mechanism of dieckol against various diseases. The pharmacological significance, current status and the dosage of multifunctional dieckol and its mechanisms have been discussed in this review. Dieckol plays an important role in apoptosis induction via inhibiting the PI3K, AKT, mTOR and FAK signaling molecules. Dieckol remarkably inhibited the lipid accumulation in high fat diet induced animal models. Dieckol, a multifaceted compound will be beneficial in attenuating the action of various diseases and it could be a potential pharmaceutical and nutraceutical compound. Therefore, the combined effects of dieckol with existing drugs and natural compounds will be studied in future to optimize its benefits. Besides limited information on the toxicological action and dosage administration of dieckol on the human was reported to date. Overall, dieckol is a prospective health-promoting compound for the development of a novel drug against numerous diseases.

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.

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.

Phloroglucinol ameliorates cognitive impairments by reducing the amyloid β peptide burden and pro-inflammatory cytokines in the hippocampus of 5XFAD mice

Among the various causative factors involved in the pathogenesis of Alzheimer's disease (AD), oxidative stress has emerged as an important factor. Phloroglucinol is a polyphenol component of phlorotannin, which is found at sufficient levels in Ecklonia cava (E. cava). Phloroglucinol has been reported to exert antioxidant activities in various tissues. Previously, we reported that the stereotaxic injection of phloroglucinol regulated synaptic plasticity in an AD mouse model. In this study, we aimed to investigate the effects of oral administration of phloroglucinol in AD. The oral administration of phloroglucinol for 2 months attenuated the impairments in cognitive function observed in 6-month-old 5X familial AD (5XFAD) mice, as assessed with the T-maze and Y-maze tests. The administration of phloroglucinol for 2 months in 5XFAD mice caused a reduction in the number of amyloid plaques and in the protein level of BACE1, a major amyloid precursor protein cleavage enzyme, together with γ-secretase. Phloroglucinol also restored the reduction in dendritic spine density and the number of mature spines in the hippocampi of 5XFAD mice. In addition, phloroglucinol-administered 5XFAD mice displayed lower protein levels of GFAP and Iba-1 and mRNA levels of TNF-α and IL-6 compared with vehicle-administered 5XFAD mice. These results demonstrated that phloroglucinol alleviated the neuropathological features and behavioral phenotypes in the 5XFAD mouse model. Taken together, our results suggest that phloroglucinol has therapeutic potential for AD treatment.

Purification of phlorotannins from Macrocystis pyrifera using macroporous resins

Phlorotannins are secondary metabolites produced by brown seaweed, which are known for their nutraceutical and pharmacological properties. The aim of this work was to determine the type of macroporous resin and the conditions of operation that improve the purification of phlorotannins extracted from brown seaweed, Macrocystis pyrifera. For the purification of phlorotannins, six resins (HP-20, SP-850, XAD-7, XAD-16N, XAD-4 and XAD-2) were assessed. The kinetic adsorption allowed determination of an average adsorption time for the resins of 9h. The highest level of purification of phlorotannins was obtained with XAD-16N, 42%, with an adsorption capacity of 183±18mgPGE/g resin, and a desorption ratio of 38.2±7.7%. According to the adsorption isotherm the best temperature of operation was 25°C, and the model that best described the adsorption properties was the Freundlich model. The purification of phlorotannins might expand their use as a bioactive substance in the food, nutraceutical and pharmaceutical industries.

Marine Pharmacology in 2012-2013: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis, and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The peer-reviewed marine pharmacology literature from 2012 to 2013 was systematically reviewed, consistent with the 1998–2011 reviews of this series. Marine pharmacology research from 2012 to 2013, conducted by scientists from 42 countries in addition to the United States, reported findings on the preclinical pharmacology of 257 marine compounds. The preclinical pharmacology of compounds isolated from marine organisms revealed antibacterial, antifungal, antiprotozoal, antituberculosis, antiviral and anthelmitic pharmacological activities for 113 marine natural products. In addition, 75 marine compounds were reported to have antidiabetic and anti-inflammatory activities and affect the immune and nervous system. Finally, 69 marine compounds were shown to display miscellaneous mechanisms of action which could contribute to novel pharmacological classes. Thus, in 2012–2013, the preclinical marine natural product pharmacology pipeline provided novel pharmacology and lead compounds to the clinical marine pharmaceutical pipeline, and contributed significantly to potentially novel therapeutic approaches to several global disease categories.

Interaction of Plant Extracts with Central Nervous System Receptors

Background: Plant extracts have been used in traditional medicine for the treatment of various maladies including neurological diseases. Several central nervous system receptors have been demonstrated to interact with plant extracts and components affecting the pharmacology and thereby potentially playing a role in human disease and treatment. For instance, extracts from Hypericum perforatum (St. John’s wort) targeted several CNS receptors. Similarly, extracts from Piper nigrum, Stephania cambodica, and Styphnolobium japonicum exerted inhibition of agonist-induced activity of the human neurokinin-1 receptor. Methods: Different methods have been established for receptor binding and functional assays based on radioactive and fluorescence-labeled ligands in cell lines and primary cell cultures. Behavioral studies of the effect of plant extracts have been conducted in rodents. Plant extracts have further been subjected to mood and cognition studies in humans. Results: Mechanisms of action at molecular and cellular levels have been elucidated for medicinal plants in support of standardization of herbal products and identification of active extract compounds. In several studies, plant extracts demonstrated affinity to a number of CNS receptors in parallel indicating the complexity of this interaction. In vivo studies showed modifications of CNS receptor affinity and behavioral responses in animal models after treatment with medicinal herbs. Certain plant extracts demonstrated neuroprotection and enhanced cognitive performance, respectively, when evaluated in humans. Noteworthy, the penetration of plant extracts and their protective effect on the blood-brain-barrier are discussed. Conclusion: The affinity of plant extracts and their isolated compounds for CNS receptors indicates an important role for medicinal plants in the treatment of neurological disorders. Moreover, studies in animal and human models have confirmed a scientific basis for the application of medicinal herbs. However, additional investigations related to plant extracts and their isolated compounds, as well as their application in animal models and the conducting of clinical trials, are required.

Dieckol, an edible seaweed polyphenol, retards rotenone-induced neurotoxicity and α-synuclein aggregation in human dopaminergic neuronal cells

Dopaminergic neurons are particularly vulnerable to oxidative stress, which may initiate a cascade of intracellular toxic events that lead to protein aggregation and subsequent cell death, causing Parkinson's disease.

The edible brown seaweed Ecklonia cava reduces hypersensitivity in postoperative and neuropathic pain models in rats

The current study was designed to investigate whether edible brown seaweed Ecklonia cava extracts exhibits analgesic effects in plantar incision and spared nerve injury (SNI) rats. To evaluate pain-related behavior, we performed the mechanical withdrawal threshold (MWT) and thermal hypersensitivity tests measured by von Frey filaments and a hot/cold plate analgesia meter. Pain-related behavior was also determined through analysis of ultrasonic vocalization. The results of experiments showed MWT values of the group that was treated with E. cava extracts by 300 mg/kg significantly increased; on the contrary, number of ultrasonic distress vocalization of the treated group was reduced at 6 h and 24 h after plantar incision operation (62.8%, p < 0.05). Moreover, E. cava 300 mg/kg treated group increased the paw withdrawal latency in hot-and cold-plate tests in the plantar incision rats. After 15 days of continuous treatment with E. cava extracts at 300 mg/kg, the treated group showed significantly alleviated SNI-induced hypersensitivity response by MWT compared with the control group. In conclusion, these results suggest that E. cava extracts have potential analgesic effects in the case of postoperative pain and neuropathic pain in rats.

Herbal Insomnia Medications that Target GABAergic Systems: A Review of the Psychopharmacological Evidence

Insomnia is a common sleep disorder which is prevalent in women and the elderly. Current insomnia drugs mainly target the γ-aminobutyric acid (GABA) receptor, melatonin receptor, histamine receptor, orexin, and serotonin receptor. GABA_A receptor modulators are ordinarily used to manage insomnia, but they are known to affect sleep maintenance, including residual effects, tolerance, and dependence. In an effort to discover new drugs that relieve insomnia symptoms while avoiding side effects, numerous studies focusing on the neurotransmitter GABA and herbal medicines have been conducted. Traditional herbal medicines, such as Piper methysticum and the seed of Zizyphus jujuba Mill var. spinosa, have been widely reported to improve sleep and other mental disorders. These herbal medicines have been applied for many years in folk medicine, and extracts of these medicines have been used to study their pharmacological actions and mechanisms. Although effective and relatively safe, natural plant products have some side effects, such as hepatotoxicity and skin reactions effects of Piper methysticum. In addition, there are insufficient evidences to certify the safety of most traditional herbal medicine. In this review, we provide an overview of the current state of knowledge regarding a variety of natural plant products that are commonly used to treat insomnia to facilitate future studies.