Dieckol, a Major Marine Polyphenol, Enhances Non-Rapid Eye Movement Sleep in Mice via the GABAA-Benzodiazepine Receptor

Novel neuropharmacological activity of citrus lime (Citrus aurantifolia): A standardized lime peel supplement enhances non-rapid eye movement sleep by activating the GABA type A receptor

Polyphenols have been well-established to exert sedative-hypnotic effects in psychopharmacology. Lime (Citrus aurantifolia) peel is rich in biologically active polyphenols; however, the effects of lime peel extract on sleep have not yet been demonstrated. A comparison was conducted in mice, between the sleep-promoting effects of a standardized lime peel supplement (SLPS) and a well-known hypnotic drug, zolpidem, and its hypnotic mechanism was investigated using in vivo and in vitro assays. The effects of SLPS on sleep were assessed using a pentobarbital-induced sleep test and sleep architecture analysis based on recording electroencephalograms and electromyograms. Additionally, a GABAA receptor binding assay, electrophysiological measurements, and in vivo animal models were used to elucidate the hypnotic mechanism. SLPS (200 and 400 mg/kg) was found to significantly decrease sleep latency and increase the amount of non-rapid eye movement sleep without altering delta activity. The hypnotic effects of SLPS were attributed to its flavonoid-rich ethyl acetate fraction. SLPS had a binding affinity to the GABA-binding site of the GABAA receptor and directly activated the GABAA receptors. The hypnotic effects and GABAA receptor activity of SLPS were completely blocked by bicuculline, a competitive antagonist of the GABAA receptor, in both in vitro and in vivo assays. To the best of our knowledge, this study is the first to demonstrate the hypnotic effects of SLPS, which acts via the GABA-binding site of the GABAA receptor. Our results suggest that lime peel, a by-product abundantly generated during juice processing, can potentially be used as a novel sedative-hypnotic.

Dietary polyphenols and sleep modulation: Current evidence and perspectives

Polyphenols are plant compounds with several biological activities. This review aims to summarize current knowledge on the potential role of polyphenols in modulating sleep. A total of 28 preclinical studies, 12 intervention studies and four observational studies exploring the role of polyphenol intake on sleep were identified. From animal studies, 26 out of the 28 studies found beneficial effects of polyphenols on sleep architecture. Three out of four human observational studies found a beneficial association between polyphenol intake and sleep parameters. And, among clinical intervention studies, eight from a total of 12 studies found some beneficial effect of polyphenol intake on various sleep parameters, although some discrepancies between studies were found. Overall, emerging evidence suggests a benefit of polyphenol intake on sleep. Several mechanisms of action have been suggested, ranging from effects on neurotransmitters to an action through the gut-brain axis. However, more research in this field is needed, emphasizing the use of nutritional doses in mechanistic studies and interventions targeting participants with sleep problems. This would allow to elucidate whether an additional biological effect of polyphenols is modulation of sleep, a behavior associated with adverse health outcomes.

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.

Anti-Inflammatory Effects of Marine Bioactive Compounds and Their Potential as Functional Food Ingredients in the Prevention and Treatment of Neuroinflammatory Disorders

Functional foods include enhanced, enriched, fortified, or whole foods that impart health benefits beyond their nutritional value, particularly when consumed as part of a varied diet on a regular basis at effective levels. Marine sources can serve as the sources of various healthy foods and numerous functional food ingredients with biological effects can be derived from these sources. Microalgae, macroalgae, crustaceans, fungi, bacteria fish, and fish by-products are the most common marine sources that can provide many potential functional food ingredients including phenolic compounds, proteins and peptides, and polysaccharides. Neuroinflammation is closely linked with the initiation and progression of various neurodegenerative diseases, including Alzheimer's disease, Huntington's disease, and Parkinson's disease. Activation of astrocytes and microglia is a defense mechanism of the brain to counter damaged tissues and detrimental pathogens, wherein their chronic activation triggers neuroinflammation that can further exacerbate or induce neurodegeneration. Currently, available therapeutic agents only provide symptomatic relief from these disorders and no therapies are available to stop or slow down the advancement of neurodegeneration. Thereffore, natural compounds that can exert a protective effect against these disorders have therapeutic potential. Numerous chemical compounds, including bioactive peptides, fatty acids, pigments, alkaloids, and polysaccharides, have already been isolated from marine sources that show anti-inflammatory properties, which can be effective in the treatment and prevention of neuroinflammatory disorders. The anti-inflammatory potential of marine-derived compounds as functional food ingredients in the prevention and treatment of neurological disorders is covered in this review.

Curcuminoids, a major turmeric component, have a sleep-enhancing effect by targeting the histamine H1 receptor

Turmeric (Curcuma longa) had been considered as a universal panacea in functional foods and traditional medicines. In recent, the sedative-hypnotic effect of turmeric extract (TE) was reported. However, sleep-promoting compounds in TE have been not yet demonstrated. Curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin) are the major constituents of turmeric being responsible for its various biological activities. Therefore, they can be first assumed to be sedative-hypnotic compounds of TE. In the present study, we aimed to investigate the effects and underlying mechanisms of curcuminoids and each constituent on the sleep-wake cycle of mice. Molecular docking studies, histamine H1 receptor (H1R) binding assays, and H1R knockout animal studies were used to investigate the molecular mechanisms underlying the sleep-promoting effects. Curcuminoids and their constituents reduced sleep latency and increased sleep duration in the pentobarbital-induced sleep test in mice. In addition, curcuminoids significantly increased the duration of NREMS and reduced sleep latency without altering the REMS and delta activity. Curcumin, demethoxycurcumin, and bisdemethoxycurcumin were predicted to interact with H1R in the molecular model. In the binding affinity assay, we found that curcuminoids, as well as their constituents, significantly bind to H1R with the K_i value of 1.49 μg mL^-1. Furthermore, sleep latency was reduced and NREMS frequency was increased following curcuminoid administration in wild-type mice but not in H1R knockout mice. Therefore, we conclude that curcuminoids reduce sleep latency and enhance the quantity of NREMS by acting as modulators of H1R, indicating their usefulness in treating insomnia.

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.

Comprehensive effects of various nutrients on sleep

Sleep problems have become common among people today. Sleep disorders are closely associated with physiological and psychological diseases. Among the ways of improving objective or subjective sleep quality, controlling elements associated with food intake can be more efficient than other methods in terms of time and cost. Therefore, the purpose of this study was to understand the effects of nutrients and natural products on sleep. An extensive literature search was conducted, and related articles were identified through online databases, such as Elsevier, Google Scholar, PubMed, Springer, and Web of Science. Expert opinion, conference abstracts, unpublished studies, and studies published in languages other than English were excluded from this review. The effects of macronutrients and diet adjustment on sleep differed. Although not all nutrients independently affect sleep, they comprehensively affect it through tryptophan metabolism. Furthermore, natural foods related to GABA have an effect on sleep similar to that of sleeping pills. Taken together, our results suggest that humans can control both their objective and subjective sleep quality based on their lifestyle and food consumption. However, until now, direct studies on the relationship between human sleep and nutrition, such as clinical trials, have been insufficient. As both objective and subjective sleep quality are the factors determining the quality of life of individuals, further studies on those are needed to improve it.

In silico investigation and potential therapeutic approaches of natural products for COVID-19: Computer-aided drug design perspective

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a substantial number of deaths around the world, making it a serious and pressing public health hazard. Phytochemicals could thus provide a rich source of potent and safer anti-SARS-CoV-2 drugs. The absence of approved treatments or vaccinations continues to be an issue, forcing the creation of new medicines. Computer-aided drug design has helped to speed up the drug research and development process by decreasing costs and time. Natural compounds like terpenoids, alkaloids, polyphenols, and flavonoid derivatives have a perfect impact against viral replication and facilitate future studies in novel drug discovery. This would be more effective if collaboration took place between governments, researchers, clinicians, and traditional medicine practitioners' safe and effective therapeutic research. Through a computational approach, this study aims to contribute to the development of effective treatment methods by examining the mechanisms relating to the binding and subsequent inhibition of SARS-CoV-2 ribonucleic acid (RNA)-dependent RNA polymerase (RdRp). The in silico method has also been employed to determine the most effective drug among the mentioned compound and their aquatic, nonaquatic, and pharmacokinetics' data have been analyzed. The highest binding energy has been reported -11.4 kcal/mol against SARS-CoV-2 main protease (7MBG) in L05. Besides, all the ligands are non-carcinogenic, excluding L04, and have good water solubility and no AMES toxicity. The discovery of preclinical drug candidate molecules and the structural elucidation of pharmacological therapeutic targets have expedited both structure-based and ligand-based drug design. This review article will assist physicians and researchers in realizing the enormous potential of computer-aided drug design in the design and discovery of therapeutic molecules, and hence in the treatment of deadly diseases.

Seafood Discards: A Potent Source of Enzymes and Biomacromolecules With Nutritional and Nutraceutical Significance

In recent times, the seafood industry is found to produce large volumes of waste products comprising shrimp shells, fish bones, fins, skins, intestines, and carcasses, along with the voluminous quantity of wastewater effluents. These seafood industry effluents contain large quantities of lipids, amino acids, proteins, polyunsaturated fatty acids, minerals, and carotenoids mixed with the garbage. This debris not only causes a huge wastage of various nutrients but also roots in severe environmental contamination. Hence, the problem of such seafood industry run-offs needs to be immediately managed with a commercial outlook. Microbiological treatment may lead to the valorization of seafood wastes, the trove of several useful compounds into value-added materials like enzymes, such as lipase, protease, chitinase, hyaluronidase, phosphatase, etc., and organic compounds like bioactive peptides, collagen, gelatin, chitosan, and mineral-based nutraceuticals. Such bioconversion in combination with a bio-refinery strategy possesses the potential for environment-friendly and inexpensive management of discards generated from seafood, which can sustainably maintain the production of seafood. The compounds that are being produced may act as nutritional sources or as nutraceuticals, foods with medicinal value. Determining utilization of seafood discard not only reduces the obnoxious deposition of waste but adds economy in the production of food with nutritional and medicinal importance, and, thereby meets up the long-lasting global demand of making nutrients and nutraceuticals available at a nominal cost.

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.

Bioactive Compounds of Nutraceutical Value from Fishery and Aquaculture Discards

Seafood by-products, produced by a range of different organisms, such as fishes, shellfishes, squids, and bivalves, are usually discarded as wastes, despite their possible use for innovative formulations of functional foods. Considering that “wastes” of industrial processing represent up to 75% of the whole organisms, the loss of profit may be coupled with the loss of ecological sustainability, due to the scarce recycling of natural resources. Fish head, viscera, skin, bones, scales, as well as exoskeletons, pens, ink, and clam shells can be considered as useful wastes, in various weight percentages, according to the considered species and taxa. Besides several protein sources, still underexploited, the most interesting applications of fisheries and aquaculture by-products are foreseen in the biotechnological field. In fact, by-products obtained from marine sources may supply bioactive molecules, such as collagen, peptides, polyunsaturated fatty acids, antioxidant compounds, and chitin, as well as catalysts in biodiesel synthesis. In addition, those sources can be processed via chemical procedures, enzymatic and fermentation technologies, and chemical modifications, to obtain compounds with antioxidant, anti-microbial, anti-cancer, anti-hypertensive, anti-diabetic, and anti-coagulant effects. Here, we review the main discards from fishery and aquaculture practices and analyse several bioactive compounds isolated from seafood by-products. In particular, we focus on the possible valorisation of seafood and their by-products, which represent a source of biomolecules, useful for the sustainable production of high-value nutraceutical compounds in our circular economy era.