Gastrointestinal modifications and bioavailability of brown seaweed phlorotannins and effects on inflammatory markers

Potential use of seaweed as a dietary supplement to mitigate enteric methane emission in ruminants

Seaweeds or marine algae exhibit diverse morphologies, sizes, colors, and chemical compositions, encompassing various species, including red, green, and brown seaweeds. Several seaweeds have received increased research attention and application in animal feeding investigations, particularly in ruminant livestock, due to their higher yield and convenient harvestability at present. Recent endeavors encompassing both in vitro and in vivo experiments have indicated that many seaweeds, particularly red seaweed (Asparagopsis taxiformis and Asparagopsis armata), contain plant secondary compounds, such as halogenated compounds and phlorotannins, with the potential to reduce enteric ruminal methane (CH4) emissions by up to 99 % when integrated into ruminant diets. This review provides an encompassing exploration of the existing body of knowledge concerning seaweeds and their impact on rumen fermentation, the toxicity of ruminal microbes, the health of animals, animal performance, and enteric ruminal CH4 emissions in both in vitro and in vivo settings among ruminants. By attaining a deeper comprehension of the implications of seaweed supplementation on rumen fermentation, animal productivity, and ruminal CH4 emissions, we could lay the groundwork for devising innovative strategies. These strategies aim to simultaneously achieve environmental benefits, reduce greenhouse gas emissions, enhance animal efficiency, and develop aquaculture and seaweed production systems, ensuring a high-quality and consistent supply chain. Nevertheless, future research is essential to elucidate the extent of the effect and gain insight into the mode of action.

In vitro Immunostimulant Activity of the Polyphenolic Extract from the Arctic Brown Algae Fucus vesiculosus

Polyphenols (PP) found in brown algae are known for their wide range of biological activities including noteworthy antitumor properties. This article presents a method for obtaining an active polyphenolic extract from the Arctic alga Fucus vesiculosus with 98% purity and radical scavenging activity equivalent to 862 mg of ascorbic acid per gram of extract. Immunostimulant effects of polyphenols were assessed in vitro using venous blood from two groups of people: healthy people (HP) and people with chronic undifferentiated lymphocytic leukemia (LP). Polyphenols activated the surface properties of immunocompetent cells. Specifically, polyphenols dose-dependently increased the percentage of cells' spreading and adhesion by 2-3 times. Additionally, polyphenols increased the number of activated lymphocytes in the LP blood to levels characteristic of HP. Given their natural origin, high activity, non-toxicity, and straightforward production process, these studied polyphenols exhibit immense potential for use as new pharmaceuticals or as active components with immunostimulatory effects.

In vitro digestion and colonic fermentation of phenolic compounds and their antioxidant potential in Australian beach-cast seaweeds

Beach-cast seaweed has recently garnered attention for its nutrient-rich composition, including proteins, carbohydrates, vitamins, minerals, and phytochemicals. This study focuses on the phenolic content and antioxidant potential of five Australian beach-cast seaweed species during in vitro digestion and colonic fermentation. The bioaccessibility of the selected phenolic compounds was estimated and short chain fatty acids (SCFAs) production was determined. Cystophora sp., showed a notable increase in phenolic content (23.1 mg GAE/g) and antioxidant capacity (0.42 mg CE/g) during the intestinal and gastric phases of in vitro digestion. Durvillaea sp. demonstrated a significant release of flavonoids (0.35 mg QE/g), while Phyllosphora comosa released high levels of tannins (0.72 mg CE/g) during the intestinal phase. During colonic fermentation, P. comosa released the highest levels of phenolic compounds (4.3 mg GAE/g) after 2 h, followed by an increase in flavonoids (0.15 mg QE/g), tannins (0.07 mg CE/g), and antioxidant activity (DPPH: 0.12 mg CE/g; FRAP: 0.61 mg CE/g) after 4 h. Moreover, P. comosa released a considerable amount of phenolic compounds during both in vitro digestion and colonic fermentation. All species consistently released phenolic compounds throughout the study. Phloroglucinol, gallic acid, and protocatechuic acid were identified as the most bioaccessible phenolic compounds in all five Australian beach-cast seaweeds in the in vitro digestion. Nevertheless, compound levels declined during the colonic fermentation phase due to decomposition and fermentation by gut microbiota. With regard to SCFAs, P. comosa displayed elevated levels of acetic (0.51 mmol/L) and propionic acid (0.36 mmol/L) at 2 h, while Durvillaea sp. showed increased butyric (0.42 mmol/L) and valeric (0.26 mmol/L) production acid after 8 h. These findings suggest that seaweed such as Cystophora sp., Durvillaea sp., and P. comosa are promising candidates for food fortification or nutraceutical applications, given their rich phenolic content and antioxidant properties that potentially offer gut health benefits.

Unraveling the bioactive interplay: seaweed polysaccharide, polyphenol and their gut modulation effect

Seaweed is rich in many unique bioactive compounds such as polyphenols and sulfated polysaccharides that are not found in terrestrial plant. The discovery of numerous biological activities from seaweed has made seaweed an attractive functional food source with the potential to be exploited for human health benefits. During food processing and digestion, cell wall polysaccharide and polyphenols commonly interact, and this may influence the nutritional properties of food. Interactions between cell wall polysaccharide and polyphenols in plant-based system has been extensively studied. However, similar interactions in seaweed have received little attention despite the vast disparity between the structural and chemical composition of plant and seaweed cell wall. This poses a challenge in extracting seaweed bioactive compounds with intact biological properties. This review aims to summarize the cell wall polysaccharide and polyphenols present in brown, red and green seaweed, and current knowledge on their potential interactions. Moreover, this review gives an overview of the gut modulation effect of seaweed polysaccharide and polyphenol.

Why is it important to understand the nature and chemistry of tannins to exploit their potential as nutraceuticals?

Tannins comprise a large group of polyphenols that can differ widely in chemical composition and molecular weight. The use of tannins dates back to antiquity, but it is only in recent years that their potential use as nutraceuticals associated with the human diet is beginning to be exploited. Although the biological effects of these phytocomplexes have been studied for many years, there are still several open questions regarding their chemistry and biotransformation. The vastness of the molecules that make up the class of tannins has made their characterisation, as well as their nomenclature and classification, a daunting task. This review has been written with the aim of bringing order to the chemistry of tannins by including aspects that are sometimes still overlooked or should be updated with new research in order to understand the potential of these phytocomplexes as active ingredients or technological components for nutraceutical products. Future trends in tannin research should address many questions that are still open, such as determining the exact biosynthetic pathways of all classes of tannins, the actual biological effects determined by the interaction of tannins with other molecules, their metabolization, and the best extraction methods, but with a view to market requirements.

Cooking, Digestion, and In Vitro Colonic Fermentation of Nigerian Wholegrains Affect Phenolic Acid Metabolism and Gut Microbiota Composition

Wholegrains contain both fibre and phenolic acids (PAs), and their gastrointestinal modifications are critical for their bioavailability and bioactivity. We evaluated the modifications on the PA profile and gut microbiota composition of selected Nigerian wholegrains, following cooking and gastrointestinal digestion. Red fonio, red millet, red sorghum, and white corn were cooked, digested, and fermented using an in vitro colonic model. A total of 26 PA derivatives were quantified in soluble and bound fractions using Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) analysis. DNA samples were analysed using 16S rRNA amplicon sequencing to profile the microbiota composition. The results show that cooking and digestion significantly affected the levels of PAs in all grains (p ≤ 0.05) compared to raw grains. Colonic fermentation resulted in a peak of total soluble PAs at 4-6 h for red sorghum and white corn and at 24 h for red millet and red fonio. Enterobacteriaceae genera were the most abundant at 24 h in all grains studied. 3-hydroxybenzaldehyde correlated positively with the relative abundance of Dorea and the mucus-degrader bacteria Akkermansia (p ≤ 0.05), whereas hydroferulic acid and isoferulic acid levels correlated negatively with Oscillospira and Ruminococcus (p ≤ 0.05), respectively. Our data indicate that cooking, digestion, and colonic fermentation affect the release of bound PAs from wholegrains and, consequently, their metabolic conversion. Furthermore, PA fermentation in the gut is associated with potentially relevant changes in the microbiota. This in vitro study provides the basis for the design of an in vivo human intervention study that can confirm the trends herein observed but also assess the impact on health outcomes.

Cochayuyo (Durvillaea incurvata) Extracts: Their Impact on Starch Breakdown and Antioxidant Activity in Pasta during In Vitro Digestion

Seaweeds, notably cochayuyo (Durvillaea incurvata), are recognized for their rich macro- and micronutrient content, along with their inhibitory effects on the α-glucosidase enzyme. The present study aims to evaluate the effectiveness of this inhibition in actual starchy food products under in vitro gastrointestinal conditions. This study utilized freeze-dried cochayuyo, extracted using hot pressurized liquid extraction with 50% ethanol at 120 °C and 1500 psi. The inhibition mechanism of α-glucosidase was determined, and the polyphenol composition of the extract was analyzed using Ultra-High-Performance Liquid Chromatography. This study further evaluated the extract's impact on starch digestibility, total phenolic content, and antioxidant capacity in pasta (noodles) as representative starchy food under gastrointestinal conditions. The results indicate that the α-glucosidase inhibition mechanism is of mixed type. Phenolic compounds, primarily tetraphloroethol, could contribute to this anti-enzymatic activity. The extract was observed to decrease starch digestibility, indicated by a lower rate constant (0.0158 vs. 0.0261 min-1) and digested starch at an infinite time (77.4 vs. 80.5 g/100 g). A significant increase (~1200 vs. ~390 µmol TROLOX/100 g) in antioxidant activity was also noted during digestion when the extract was used. Thus, this study suggests that the cochayuyo extract can reduce starch digestion and enhance antioxidant capacity under gastrointestinal conditions.

Anti-Hypercholesterolemia Effects of Edible Seaweed Extracts and Metabolomic Changes in Hep-G2 and Caco-2 Cell Lines

Hypercholesterolemia is a major risk for the development of cardiovascular diseases (CVDs), the main cause of mortality worldwide, and it is characterized by high levels of circulating cholesterol. The drugs currently available for hypercholesterolemia control have several side effects, so it is necessary to develop new effective and safer therapies. Seaweeds serve as sources of several bioactive compounds with claimed beneficial effects. Eisenia bicyclis (Aramé) and Porphyra tenera (Nori) are edible seaweeds that were previously recognized as rich in bioactive compounds. In the present study, we aim to evaluate the anti-hypercholesterolemia effect of these two seaweed extracts and their health potential. Both extracts, but more efficiently Aramé extract, have liver 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) inhibitory activity as well as the capability to reduce approximately 30% of cholesterol permeation through human Caco-2 cells by simulating the intestinal lining, which is a target for hypercholesterolemia treatments. An untargeted metabolomic assay on human intestinal Caco-2 and liver Hep-G2 cell lines exposed to Aramé and Nori extracts revealed changes in the cells' metabolism, indicating the extracts' health beneficial effects. The metabolic pathways affected by exposure to both extracts were associated with lipid metabolism, such as phospholipids, and fatty acid metabolism, amino acid pathways, cofactors, vitamins, and cellular respiration metabolism. The effects were more profound in Aramé-treated cells, but they were also observed in Nori-exposed cells. The metabolite modifications were associated with the protection against CVDs and other diseases and to the improvement of the cells' oxidative stress tolerance. The results obtained for the anti-hypercholesterolemia properties, in addition to the revelation of the positive impact on cell metabolism, offer an important contribution for further evaluation of these seaweed extracts as functional foods or for CVD prevention.

Potential of Seaweeds to Mitigate Production of Greenhouse Gases during Production of Ruminant Proteins

The potential of seaweed to mitigate methane is real and studies with red seaweeds have found reductions in methane produced from ruminants fed red seaweeds in the region of 60-90% where the active compound responsible for this is bromoform. Other studies with brown and green seaweeds have observed reductions in methane production of between 20 and 45% in vitro and 10% in vivo. Benefits of feeding seaweeds to ruminants are seaweed specific and animal species-dependent. In some instances, positive effects on milk production and performance are observed where selected seaweeds are fed to ruminants while other studies note reductions in performance traits. A balance between reducing methane and maintaining animal health and food quality is necessary. Seaweeds are a source of essential amino acids and minerals however, and offer huge potential for use as feeds for animal health maintenance once formulations and doses are correctly prepared and administered. A negative aspect of seaweed use for animal feed currently is the cost associated with wild harvest and indeed aquaculture production and improvements must be made here if seaweed ingredients are to be used as a solution to control methane production from ruminants for continued production of animal/ruminant sourced proteins in the future. This review collates information concerning different seaweeds and how they and their constituents can reduce methane from ruminants and ensure sustainable production of ruminant proteins in an environmentally beneficial manner.

Bioaccessibility and bioactivities of phenolic compounds from microalgae during in vitro digestion and colonic fermentation

Microalgae are a developing novel source of carbohydrates, phenolic compounds, carotenoids and proteins. In this study, in vitro digestion and colonic fermentation were conducted to examine the total phenolic content and potential antioxidant activity of four microalgal species (Chlorella sp., Spirulina sp., Dunaliella sp., and Isochrysis sp.). The bioaccessibility of targeted phenolic compounds and the short-chain fatty acid (SCFA) production were also estimated. Particularly, Spirulina sp. exhibited the highest total phenolic content (TPC) and free radical scavenging (2,2'-diphenyl-1-picrylhydrazyl, DPPH) capacity after gastrointestinal digestion of 7.93 mg gallic acid equivalents (GAE) per g and 2.35 mg Trolox equivalents (TE) per g. Meanwhile, it had the highest total flavonoid content (TFC) of 1.07 quercetin equivalents (QE) per g after 8 h of colonic fermentation. Dunaliella sp. and Isochrysis sp. showed comparable ferric reducing antioxidant power (FRAP) of 4.96 and 4.45 mg QE per g after 4 h of faecal reaction, respectively. p-hydroxybenzoic and caffeic acid almost completely decomposed after the intestine and fermented in the colon with the gut microflora. In Dunaliella sp. and Isochrysis sp., these phenolic acids were found in the colonic fermented residual, probably due to the presence of dietary fibre and the interactions with other components. All four species reached the highest values of SCFA production after 16 h, except Spirulina sp., which displayed the most increased total SCFA production after 8 h of fermentation. It is proposed that Spirulina sp. could be more beneficial to gut health.

Overview of Phlorotannins' Constituents in Fucales

Fucales are an order within the Phaeophyceae that include most of the common littoral seaweeds in temperate and subtropical coastal regions. Many species of this order have long been a part of human culture with applications as food, feedand remedies in folk medicine. Apart from their high nutritional value, these seaweeds are also a well-known reservoir of multiple bioactive compounds with great industrial interest. Among them, phlorotannins, a unique and diverse class of brown algae-exclusive phenolics, have gathered much attention during the last few years due to their numerous potential health benefits. However, due to their complex structural features, combined with the scarcity of standards, it poses a great challenge to the identification and characterization of these compounds, at least with the technology currently available. Nevertheless, much effort has been taken towards the elucidation of the structural features of phlorotannins, which have resulted in relevant insights into the chemistry of these compounds. In this context, this review addresses the major contributions and technological advances in the field of phlorotannins extraction and characterization, with a particular focus on Fucales.

A Bioactive Substance Derived from Brown Seaweeds: Phlorotannins

Phlorotannins are a type of natural active substance extracted from brown algae, which belong to a type of important plant polyphenol. Phloroglucinol is the basic unit in its structure. Phlorotannins have a wide range of biological activities, such as antioxidant, antibacterial, antiviral, anti-tumor, anti-hypertensive, hypoglycemic, whitening, anti-allergic and anti-inflammatory, etc. Phlorotannins are mainly used in the fields of medicine, food and cosmetics. This paper reviews the research progress of extraction, separation technology and biological activity of phlorotannins, which will help the scientific community investigate the greater biological significance of phlorotannins.

Red seaweed extracts reduce methane production by altering rumen fermentation and microbial composition in vitro

A series of in vitro batch culture incubations were carried out to investigate changes in rumen fermentation characteristics, methane (CH4) production, and microbial composition in response to supplementation with five different red seaweed species (Amphiroa anceps, AANC; Asparagopsis taxiformis, ATAX; Chondracanthus tenellus, CTEN; Grateloupia elliptica, GELL; and Gracilaria parvispora, GPAR). Prior to the incubations, the total flavonoid and polyphenol content of the red seaweed extracts was quantified. The incubated substrate consisted of timothy hay and corn grain [60:40 dry matter (DM) basis]. Treatments were substrate mixtures without seaweed extract (CON) or substrate mixtures supplemented with 0.25 mg/mL of red seaweed extract. Samples were incubated for 6, 12, 24, 36, and 48 h. Each sample was incubated in triplicates in three separate runs. In vitro DM degradability, fermentation parameters (i.e., pH, volatile fatty acids, and ammonia nitrogen), total gas production, and CH4 production were analyzed for all time points. Microbial composition was analyzed using 16S rRNA amplicon sequencing after 24 h of incubation. The highest CH4 reduction (mL/g DM, mL/g digested DM, and % of total gas production) was observed in ATAX (51.3, 50.1, and 51.5%, respectively, compared to CON; P < 0.001) after 12 h of incubation. The other red seaweed extracts reduced the CH4 production (mL/g DM; P < 0.001) in the range of 4.6–35.0% compared to CON after 24 h of incubation. After 24 h of incubation, supplementation with red seaweed extracts tended to increase the molar proportion of propionate (P = 0.057) and decreased the acetate to propionate ratio (P = 0.033) compared to the CON. Abundances of the genus Methanobrevibacter and total methanogens were reduced (P = 0.050 and P = 0.016) by red seaweed extract supplementation. The linear discriminant analysis effect size (P < 0.05, LDA ≥ 2.0) showed that UG Succinivibrionaceae, Anaeroplasma, and UG Ruminococcaceae, which are associated with higher propionate production, starch degradation, and amylase activity were relatively more abundant in red seaweed extracts than in the CON. Our results suggest that supplementation with red seaweed extracts altered the microbiota, leading to the acceleration of propionate production and reduction in CH4 production.

Influence of Oxidation and Dialysis of Phlorotannins on Bioactivity and Composition of Ultrasound-Assisted Extracts from Ascophyllum nodosum

The isolation and chemical characterization of phlorotannins has gained special attention in recent years due to their specific health-promoting benefits. Flow-cell ultrasound-assisted extraction (90 W/cm2 of sonication power, 2 min of retention time and 20 g solvent/g algae of liquid-solid ratio) was carried out by using double-distilled water (WE) and acetone:water mixture (AWE) as extraction solvents. The AWE showed a higher total polyphenols content (TPC), carbohydrates (CHOs) and antioxidant activities than WE. However, when the WE was purified by using Amberlite XAD16 column, the purified WE (PWE) showed similar a TPC, decreased CHOs and increased antioxidant activity compared to WE. The oxidation of the PWE extract was evaluated under natural, forced and severe oxidation condition for 120 h. Only severe oxidation conditions were able to significantly reduce TPC and antioxidant activities. PWE was dialyzed (20, 10, 3.5 and 2 kDa). The main bioactive fraction of phlorotannins was obtained from 10 to 20 kDa. CHOs were distributed in fractions below 20 kDa. MALDI-TOF analysis was performed for PWE, PD20 and PD2 extracts to analyze the degree of polymerization of phlorotannins, which ranged from 4 to 17 phloroglucinol units/molecule. Fragmentation patterns allowed the proximate identification of several phlorotannins in Ascophyllum nodosum extracts.

Ascophyllum nodosum and Fucus vesiculosus Extracts Improved Lipid Metabolism and Inflammation in High-Energy Diet-Induced Hyperlipidemia Rats

Ascophyllum nodosum and Fucus vesiculosus both contain unique polyphenols called phlorotannins. Phlorotannins reportedly possess various pharmacological activities. A previous study reported that the activity of phlorotannin is strongly correlated with the normalization of metabolic function, and phlorotannins are extremely promising nutrients for use in the treatment of metabolic syndrome. To date, no study has explored the antihyperlipidemic effects of phlorotannins from A. nodosum and F. vesiculosus in animal models. Therefore, in the present study, we investigated the effects of phlorotannins using a rat model of high-energy diet (HED)-induced hyperlipidemia. The results showed that the rats that were fed an HED and treated with phlorotannin-rich extract from A. nodosum and F. vesiculosus had significantly lower serum fasting blood sugar (FBS), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol (TC), triacylglyceride (TG) and free fatty acids (FFAs) levels and hepatic TG level and had higher serum insulin, high-density lipoprotein cholesterol (HDL-C) levels and lipase activity in their fat tissues than in the case with the rats that were fed the HED alone. A histopathological analysis revealed that phlorotannin-rich extract could significantly reduce the size of adipocytes around the epididymis. In addition, the rats treated with phlorotannin-rich extract had significantly lowered interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) levels and increased superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities than did those in the HED group. These results suggested that the phlorotannin-rich extract stimulated lipid metabolism and may have promoted lipase activity in rats with HED-induced hyperlipidemia. Our results indicated that A. nodosum and F. vesiculosus, marine algae typically used as health foods, have strong antihyperlipidemic effects and may, therefore, be useful for preventing atherosclerosis. These algae may be incorporated into antihyperlipidemia pharmaceuticals and functional foods.

Wholegrain fermentation affects gut microbiota composition, phenolic acid metabolism and pancreatic beta cell function in a rodent model of type 2 diabetes

The intestinal microbiota plays an important role in host metabolism via production of dietary metabolites. Microbiota imbalances are linked to type 2 diabetes (T2D), but dietary modification of the microbiota may promote glycemic control. Using a rodent model of T2D and an in vitro gut model system, this study investigated whether differences in gut microbiota between control mice and mice fed a high-fat, high-fructose (HFHFr) diet influenced the production of phenolic acid metabolites following fermentation of wholegrain (WW) and control wheat (CW). In addition, the study assessed whether changes in metabolite profiles affected pancreatic beta cell function. Fecal samples from control or HFHFr-fed mice were fermented in vitro with 0.1% (w/v) WW or CW for 0, 6, and 24 h. Microbiota composition was determined by bacterial 16S rRNA sequencing and phenolic acid (PA) profiles by UPLC-MS/MS. Cell viability, apoptosis and insulin release from pancreatic MIN6 beta cells and primary mouse islets were assessed in response to fermentation supernatants and selected PAs. HFHFr mice exhibited an overall dysbiotic microbiota with an increase in abundance of proteobacterial taxa (particularly Oxalobacteraceae) and Lachnospiraceae, and a decrease in Lactobacillus. A trend toward restoration of diversity and compositional reorganization was observed following WW fermentation at 6 h, although after 24 h, the HFHFr microbiota was monodominated by Cupriavidus. In parallel, the PA profile was significantly altered in the HFHFr group compared to controls with decreased levels of 3-OH-benzoic acid, 4-OH-benzoic acid, isoferulic acid and ferulic acid at 6 h of WW fermentation. In pancreatic beta cells, exposure to pre-fermentation supernatants led to inhibition of insulin release, which was reversed over fermentation time. We conclude that HFHFr mice as a model of T2D are characterized by a dysbiotic microbiota, which is modulated by the in vitro fermentation of WW. The differences in microbiota composition have implications for PA profile dynamics and for the secretory capacity of pancreatic beta cells.

Impact of Gastrointestinal Digestion on the Anti-Inflammatory Properties of Phlorotannins from Himanthalia elongata

A phlorotannin extract was obtained from Himanthalia elongata, revealing a profile rich in fucophlorethol-type and carmalol-type compounds. When subjected to simulated gastrointestinal digestion, its levels of total phlorotannins and antioxidant activity, measured in vitro via NO^● and O₂^●− scavenging assays, were reduced, thus suggesting that these compounds’ integrity and bioactivity are negatively affected by the digestive process. Nevertheless, when undigested vs. digested extracts were used on lipopolysaccharide-stimulated Raw 264.7 macrophages, both showed a strong inhibitory effect on the cellular NO^● production. In fact, although not statistically significant, the digested extract revealed a tendentially stronger effect compared to its undigested counterpart, suggesting that even though there is a decrease in the phlorotannins’ concentration after digestion, with a consequent loss of their scavenging properties, the possible degradation products being formed may exert their effects through the modulation of the intracellular signaling mechanisms. Overall, this study not only contributes to a better understanding of the phlorotannins’ composition of the species H. elongata, but also shows that, although the digestive process may affect the integrity and concentration of these compounds, this does not necessarily translate into loss of bioactivity, in particular the anti-inflammatory activity, probably owing to the bioactive effects that the degradation products of these phenolics may have at an intracellular level.

Role of natural products towards the SARS-CoV-2: A critical review

Despite the fact that various therapeutic compounds are being investigated, there is still a scarcity of effective and reliable therapeutic regimens to treat COVID-19. Ever since the COVID-19 pandemic, a diversity of traditional herbal treatments has been investigated to cure infected people, either alone or in conjunction with mainstream pharmaceuticals, with encouraging outcomes. In this article, we look at the latest research on the usage of natural products to alleviate the severity of COVID-19. To determine the activity of the natural products, act against SARS-CoV-2 to various targets like M^pro, ACE-II, papain-like, chymotrypsin-like proteases, and some antiviral targets. The processes underlying this preventative or therapeutic action are also examined. We used PubMed, Scopus, Google Scholar, and the WHO site to perform our review. The anti-SARS-CoV-2 impacts of various herbal extracts and purified compounds may be mediated via direct prevention of viral replication or entrance. Interestingly, certain items might avert SARS-CoV-2 from infecting human cells by blocking the ACE-2 protein or the serine protease TMPRRS2. Natural products have also been stated to suppress proteins intricate in the virus life cycle, like papain-like and chymotrypsin-like proteases. To conclude, natural products can be used alone or in combination as remedies or treatments for COVID-19. In addition, their compositions may provide insight into the development of effective and reliable antiviral drugs.

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The COVID-19 pandemic caused by a novel coronavirus SARS-CoV-2, resulted in thousands of deaths across the world.

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Globally, numerous studies and researchers have recently started fighting this virus.

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In this article, we look at the latest research on the usage of natural products to alleviate the severity of COVID-19.

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The anti-SARS-CoV-2 impacts of various herbal extracts and purified compounds may be mediated via direct prevention of viral replication or entrance.

Seaweed-Derived Phlorotannins: A Review of Multiple Biological Roles and Action Mechanisms

Phlorotannins are a group of phenolic secondary metabolites isolated from a variety of brown algal species belonging to the Fucaceae, Sargassaceae, and Alariaceae families. The isolation of phlorotannins from various algal species has received a lot of interest owing to the fact that they have a range of biological features and are very biocompatible in their applications. Phlorotannins have a wide range of therapeutic biological actions, including antimicrobial, antidiabetic, antioxidant, anticancer, anti-inflammatory, anti-adipogenesis, and numerous other biomedical applications. The current review has extensively addressed the application of phlorotannins, which have been extensively investigated for the above-mentioned biological action and the underlying mechanism of action. Furthermore, the current review offers many ways to use phlorotannins to avoid certain downsides, such as low stability. This review article will assist the scientific community in investigating the greater biological significance of phlorotannins and developing innovative techniques for treating both infectious and non-infectious diseases in humans.

The Immunomodulating Effect of Phlorotannins from a Brown Alga, Eisenia nipponica, on Mice Stimulated with Ovalbumin through T Cell Regulation

The immunomodulating effect of phlorotannin was investigated in mice stimulated by ovalbumin. When analyzing the main components of phlorotannin concentrate (PTC) from Eisenia nipponica, seven phlorotannins [eckol, 6,6'-bieckol, 6,8'-bieckol, 8,8'-bieckol, dieckol, phlorofucofuroeckol (PFF)-A, and PFF-B] were detected. These phlorotannins accounted for approximately 80% of PTC. Oral administration of PTC to mice daily for 21 days reduced serum immunoglobulin E (IgE) and total IgG1 levels attributable to Th2 cells. The production of splenic cytokines [interleukin (IL)-10 and transforming growth factor-β1] and Treg cell-mediated expression of forkhead box protein P3 mRNA were significantly increased whereas the production of inflammatory cytokines (interferon-γ, IL-4, IL-5, and IL-17) by Th1, Th2, and Th17 cells was markedly suppressed. IL-21 production and basic leucine zipper ATF-like transcription factor mRNA expression attributable to follicular helper T (Tfh) cells were also suppressed. Flow cytometric analyses demonstrated increased number of Treg cells despite a decrease in the total T cell population. An increase in total B cells was also observed by the flow cytometric analyses in addition to increases in IL-10 production, which activates B cells. In contrast, the significantly suppressed production of inflammatory cytokines and moderate increase in Treg cell subpopulation indicated a direct impact of PTC on inflammatory lymphocytes (Th1, Th2, Th17, and Tfh). Thus, PTC may exert antiallergic effects by immunomodulation of T cells and inactivation of inflammatory lymphocyte.

Encapsulation of phlorotannins from edible brown seaweed in chitosan: Effect of fortification on bioactivity and stability in functional foods

Phlorotannins are a family of proven therapeutic agents. However, low stability disturbs their full bioactivity expression in the human body. Hence, this study focused on preserving their vitality through encapsulation. Phlorotannins isolated from Sargassum ilicifolium were encapsulated in the chitosan-tripolyphosphate carrier. Their storage stability, processing stability, and bioactivity retention upon in vitro digestion were determined. Results revealed the highest total phlorotannin content (TPC) of 854.38 ± 48 mg Phloroglucinol Equivalence/g in the semi-purified ethyl acetate fraction while the NMR spectrum and the LCMS profile revealed the isolation of phlorotannins in it. Storage at -18℃ and 4℃ temperatures preserved thrice both the encapsulated and non-encapsulated phlorotannins than ambient conditions. Encapsulated compound reported 56.4% of TPC retention at 175 ℃ processing temperature. Fermented fraction of encapsulated form showed significantly higher (p < 0.05) antioxidant activities and TPC (0.23 ± 0.03 mg/mL) suggesting the potential for targeted delivery of phlorotannins to their absorption sites through encapsulation.

Biological Potential, Gastrointestinal Digestion, Absorption, and Bioavailability of Algae-Derived Compounds with Neuroprotective Activity: A Comprehensive Review

Currently, there is no known cure for neurodegenerative disease. However, the available therapies aim to manage some of the symptoms of the disease. Human neurodegenerative diseases are a heterogeneous group of illnesses characterized by progressive loss of neuronal cells and nervous system dysfunction related to several mechanisms such as protein aggregation, neuroinflammation, oxidative stress, and neurotransmission dysfunction. Neuroprotective compounds are essential in the prevention and management of neurodegenerative diseases. This review will focus on the neurodegeneration mechanisms and the compounds (proteins, polyunsaturated fatty acids (PUFAs), polysaccharides, carotenoids, phycobiliproteins, phenolic compounds, among others) present in seaweeds that have shown in vivo and in vitro neuroprotective activity. Additionally, it will cover the recent findings on the neuroprotective effects of bioactive compounds from macroalgae, with a focus on their biological potential and possible mechanism of action, including microbiota modulation. Furthermore, gastrointestinal digestion, absorption, and bioavailability will be discussed. Moreover, the clinical trials using seaweed-based drugs or extracts to treat neurodegenerative disorders will be presented, showing the real potential and limitations that a specific metabolite or extract may have as a new therapeutic agent considering the recent approval of a seaweed-based drug to treat Alzheimer’s disease.

Phlorotannins of the Brown Algae Sargassum vulgare from the Mediterranean Sea Coast

Brown seaweeds are a good source of bioactive compounds, particularly of phlorotannins, which may exert a wide spectrum of pharmacological properties. In the present study, phlorotannins of S. vulgare were extracted using a 70% acetone solution and the crude extract was further purified through liquid–liquid partition, giving rise to n-hexane, ethyl acetate and aqueous residue fractions. The crude extract and the purified fractions were evaluated for potential antioxidant abilities as well as for inhibitory potential towards the digestive enzymes α-amylase and pancreatic lipase, and anti-inflammatory potential through the hindering of albumin denaturation. Overall, the ethyl acetate fraction was the richest in phlorotannins (9.4 ± 0.03 mg PGE/g) and was also the most promising regarding the tested bioactive properties. Of note, its inhibitory potential towards α-amylase was about nine times that of the commercial drug acarbose and its inhibitory activity against high temperature-induced protein denaturation was superior to that of the non-steroidal drug ketoprofen. According to UHPLC-DAD-ESI-MS/MS analysis, this fraction contained a range of phlorotannins with at least six units of phloroglucinol, including dibenzodioxine-1,3,6,8-tetraol, fuhalol, pentaphlorethol, fucopentaphlorethol and dihydroxypentafuhalol, in addition to several less common phlorotannin sulfate derivatives.

Molecular Targets of Brown Algae Phlorotannins for the Therapy of Inflammatory Processes of Various Origins

Inflammatory reactions are part of a complex biological response that plays a vital role in the appearance of various stimuli resulting from tissue and cell damage, the invasion of pathogenic bacteria, and the formation of the subsequent adaptive immune response. The production of many triggers and mediators of inflammation, which are inducers of pro-inflammatory factors, is controlled by numerous differentiation programs, through which inflammation is resolved and tissue homeostasis is restored. However, prolonged inflammatory responses or dysregulation of pro-inflammatory mechanisms can lead to chronic inflammation. Modern advances in biotechnology have made it possible to characterize the anti-inflammatory activity of phlorotannins, polyphenolic compounds from brown seaweed, and the mechanisms by which they modulate the inflammatory response. The purpose of this review is to analyze and summarize the results of numerous experimental in vitro and in vivo studies, illustrating the regulatory mechanisms of these compounds, which have a wide range of biological effects on the body. The results of these studies and the need for further research are discussed.

Effects of different extraction methods on contents, profiles, and antioxidant abilities of free and bound phenolics of Sargassum polycystum from the South China Sea

Total phenolic content (TPC), phenolic profiles, and antioxidant activity of free and bound extracts of Sargassum polycystum, obtained by different extraction solvents and hydrolysis methods, were investigated. Aqueous acetone afforded the highest free TPC and antioxidant ability, followed by aqueous ethanol and aqueous methanol. Twelve free phenolic compounds were identified by ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS), including two hydroxycinnamic acids, seven flavonoids, one stilbene, and two phlorotannins. Three to nine different free phenolic compounds were extracted by these solvents with different compositions, including nine by 70% acetone and eight by 70% methanol, 70% ethanol, and 50% ethanol. The highest total content of free phenolic compounds determined by high-performance liquid chromatography-diode array detection was obtained from 70% ethanol. Alkaline hydrolysis afforded higher bound TPC (274.27 mg GAE/100 g DW) and antioxidant ability than acid hydrolysis. Five bound phenolic compounds were characterized by UHPLC-MS and five were released from alkaline hydrolysis, whereas two were released from acid hydrolysis. Total content of bound phenolic compounds released by alkaline hydrolysis was 14.68-fold higher than that by acid hydrolysis. The free and bound TPC, phenolic profiles, and antioxidant activities depended on the extraction solvent used. These results indicate that S. polycystum is a potentially useful antioxidant source and contribute to the development of seaweed-based functional foods. PRACTICAL APPLICATION: Phenolics are usually divided into free and bound forms based on their extractability and interaction with cell wall components. The nutritional effects of bound phenolics in algae have long been neglected. These topics contribute to the development of seaweed-based functional foods.

Evaluation on Intestinal Permeability of Phlorotannins Using Caco-2 Cell Monolayers

Among the phlorotannins of seaweed polyphenols, eckols which have a dibenzodioxin linkage are known to have various physiological functions. The purpose of this study was to investigate the intestinal epithelial absorption of eckols using Caco-2 cell monolayers of the small intestinal membrane model. Each compound permeated from the apical (AP) side to the basolateral (BL) side in the monolayers was identified and quantitated by liquid chromatography-mass spectrometry with electrospray ionization. In the transport assays using five types of eckols (eckol, fucofuroeckol A, phlorofucofuroeckol A, dieckol, and 8,8'-bieckol), only the monomeric eckol showed limited transepithelial absorption with relatively small apparent permeability values (0.30  ±  0.04  ×  10−8 cm/s). Analyzing the Hanks’ balanced salt solution in the receiver on the BL side showed that phloroglucinol was detected in all experimental sections using eckols, and it's concentration increased with time over the course of the incubation. The other molecules corresponding to the unconjugated and conjugated metabolites of eckols were not detected in the AP and BL sides through the assays. These results suggest that eckols, including monomeric eckol, may be decomposed into phloroglucinol in the intestinal epithelium and the resulting phloroglucinol permeates to the BL side.

The role of seaweed as a potential dietary supplementation for enteric methane mitigation in ruminants: Challenges and opportunities

Seaweeds are macroalgae, which can be of many different morphologies, sizes, colors, and chemical profiles. They include brown, red, and green seaweeds. Brown seaweeds have been more investigated and exploited in comparison to other seaweed types for their use in animal feeding studies due to their large sizes and ease of harvesting. Recent in vitro and in vivo studies suggest that plant secondary compound-containing seaweeds (e.g., halogenated compounds, phlorotannins, etc.) have the potential to mitigate enteric methane (CH4) emissions from ruminants when added to the diets of beef and dairy cattle. Red seaweeds including Asparagopsis spp. are rich in crude protein and halogenated compounds compared to brown and green seaweeds. When halogenated-containing red seaweeds are used as the active ingredient in ruminant diets, bromoform concentration can be used as an indicator of anti-methanogenic properties. Phlorotannin-containing brown seaweed has also the potential to decrease CH4 production. However, numerous studies examined the possible anti-methanogenic effects of marine seaweeds with inconsistent results. This work reviews existing data associated with seaweeds and in vitro and in vivo rumen fermentation, animal performance, and enteric CH4 emissions in ruminants. Increased understanding of the seaweed supplementation related to rumen fermentation and its effect on animal performance and CH4 emissions in ruminants may lead to novel strategies aimed at reducing greenhouse gas emissions while improving animal productivity.

Recent Advances in Research on Polyphenols: Effects on Microbiota, Metabolism, and Health

Polyphenols have attracted huge interest among researchers of various disciplines because of their numerous biological activities, such as antioxidative, antiinflammatory, antiapoptotic, cancer chemopreventive, anticarcinogenic, and antimicrobial properties, and their promising applications in many fields, mainly in the medical, cosmetics, dietary supplement and food industries. In this review, the latest scientific findings in the research on polyphenols interaction with the microbiome and mitochondria, their metabolism and health beneficial effects, their involvement in cognitive diseases and obesity development, as well as some innovations in their analysis, extraction methods, development of cosmetic formulations and functional food are summarized based on the papers presented at the 13th World Congress on Polyphenol Applications. Future implications of polyphenols in disease prevention and their strategic use as prophylactic measures are specifically addressed. Polyphenols may play a key role in our tomorrow´s food and nutrition to prevent many diseases.

Extraction and Nano-Sized Delivery Systems for Phlorotannins to Improve Its Bioavailability and Bioactivity

This review aims to provide an informative summary of studies on extraction and nanoencapsulation of phlorotannins to improve their bioavailability and bioactivity. The origin, structure, and different types of phlorotannins were briefly discussed, and the extraction/purification/characterization methods for phlorotannins were reviewed, with a focus on techniques to improve the bioactivities and bioavailability of phlorotannins via nano-sized delivery systems. Phlorotannins are promising natural polyphenol compounds that have displayed high bioactivities in several areas: anticancer, anti-inflammation, anti-HIV, antidiabetic, and antioxidant. This review aims to provide a useful reference for researchers working on developing better utilization strategies for phlorotannins as pharmaceuticals, therapeuticals, and functional food supplements.

Does timing of phytonutrient intake influence the suppression of postprandial oxidative stress? A systematic literature review

BACKGROUND

Postprandial oxidative stress markers in blood are generated transiently from various tissues and cells following high-fat and/or high-carbohydrate (HFHC) meals, and may be suppressed by certain phytonutrients, such as polyphenols and carotenoids. However, the transient presence of phytonutrients in circulation suggests that timing of consumption, relative to the meal, could be important. This systematic review investigates the effect of timing of phytonutrient intake on blood markers of postprandial oxidative processes.

METHOD

EMBASE, Medline, Scopus and Web of Science were searched up to December 2020. Eligible studies met the criteria: 1) healthy human adults; 2) phytonutrient(s) consumed in solid form within 24 h of a HFHC meal; 3) postprandial measurements of oxidative stress or antioxidants in blood; and 4) controlled study design. Cohen's d effect sizes were calculated to compare studies.

RESULTS

Nine studies, involving 256 participants, were included. Phytonutrients were consumed either at the same time, 1 h before, or the day (>12 h) before a HFHC meal. Significant decreases in blood markers - plasma lipid hydroperoxides, plasma malondialdehyde, serum sNox2-dp, serum 8-iso-PGF2α, platelet p47phox phosphorylation, and Keap-1 and p47phox protein levels in mononuclear cells (MNCs) - were observed where the phytonutrient was consumed together with the challenge meal (n = 4). Lack of any effect on oxidative stress markers was observed where phytonutrients were consumed with (n = 1), 1 h before (n = 1), and the day before (n = 2) the HFHC meal.

CONCLUSION

Phytonutrients consumed with a HFHC meal significantly suppressed some markers of oxidative stress in blood. Although there were only a limited number of studies, it appears that suppression appeared effective at the time of peak phytonutrient concentration in plasma. However, further studies are required to confirm the observations and systematically optimise the effect of timing.

Seaweed-Based Molecules and Their Potential Biological Activities: An Eco-Sustainable Cosmetics

Amongst the countless marine organisms, seaweeds are considered as one of the richest sources of biologically active ingredients having powerful biological activities. Seaweeds or marine macroalgae are macroscopic multicellular eukaryotic photosynthetic organisms and have the potential to produce a large number of valuable compounds, such as proteins, carbohydrates, fatty acids, amino acids, phenolic compounds, pigments, etc. Since it is a prominent source of bioactive constituents, it finds diversified industrial applications viz food and dairy, pharmaceuticals, medicinal, cosmeceutical, nutraceutical, etc. Moreover, seaweed-based cosmetic products are risen up in their demands by the consumers, as they see them as a promising alternative to synthetic cosmetics. Normally it contains purified biologically active compounds or extracts with several compounds. Several seaweed ingredients that are useful in cosmeceuticals are known to be effective alternatives with significant benefits. Many seaweeds' species demonstrated skin beneficial activities, such as antioxidant, anti-melanogenesis, antiaging, photoprotection, anti-wrinkle, moisturizer, antioxidant, anti-inflammatory, anticancer and antioxidant properties, as well as certain antimicrobial activities, such as antibacterial, antifungal and antiviral activities. This review presents applications of bioactive molecules derived from marine algae as a potential substitute for its current applications in the cosmetic industry. The biological activities of carbohydrates, proteins, phenolic compounds and pigments are discussed as safe sources of ingredients for the consumer and cosmetic industry.

Impact of Phlorotannin Extracts from Fucus vesiculosus on Human Gut Microbiota

Recent studies indicate that plant polyphenols could be pointed as potential prebiotic candidates since they may interact with the gut microbiota, stimulating its growth and the production of metabolites. However, little is known about the fate of brown seaweeds' phlorotannins during their passage throughout the gastrointestinal tract. This work aimed to evaluate the stability and bioaccessibility of Fucus vesiculosus phlorotannins after being submitted to a simulated digestive process, as well as their possible modulatory effects on gut microbiota and short-chain fatty acids production following a fermentation procedure using fecal inoculates to mimic the conditions of the large intestine. The stability of phlorotannins throughout the gastrointestinal tract was reduced, with a bioaccessibility index between 2 and 14%. Moreover, slight alterations in the growth of certain commensal bacteria were noticed, with Enterococcus spp. being the most enhanced group. Likewise, F. vesiculosus phlorotannins displayed striking capacity to enhance the levels of propionate and butyrate, which are two important short-chain fatty acids known for their role in intestinal homeostasis. In summary, this work provides valuable information regarding the behavior of F. vesiculosus phlorotannins along the gastrointestinal tract, presenting clear evidence that these compounds can positively contribute to the maintenance of a healthy gastrointestinal condition.

Brown Algae Phlorotannins: A Marine Alternative to Break the Oxidative Stress, Inflammation and Cancer Network

According to the WHO, cancer was responsible for an estimated 9.6 million deaths in 2018, making it the second global leading cause of death. The main risk factors that lead to the development of this disease include poor behavioral and dietary habits, such as tobacco use, alcohol use and lack of fruit and vegetable intake, or physical inactivity. In turn, it is well known that polyphenols are deeply implicated with the lower rates of cancer in populations that consume high levels of plant derived foods. In this field, phlorotannins have been under the spotlight in recent years since they have shown exceptional bioactive properties, with great interest for application in food and pharmaceutical industries. Among their multiple bioactive properties, phlorotannins have revealed the capacity to interfere with several biochemical mechanisms that regulate oxidative stress, inflammation and tumorigenesis, which are central aspects in the pathogenesis of cancer. This versatility and ability to act either directly or indirectly at different stages and mechanisms of cancer growth make these compounds highly appealing for the development of new therapeutical strategies to address this world scourge. The present manuscript revises relevant studies focusing the effects of phlorotannins to counteract the oxidative stress-inflammation network, emphasizing their potential for application in cancer prevention and/or treatment.

Seaweed Components as Potential Modulators of the Gut Microbiota

Macroalgae, or seaweeds, are a rich source of components which may exert beneficial effects on the mammalian gut microbiota through the enhancement of bacterial diversity and abundance. An imbalance of gut bacteria has been linked to the development of disorders such as inflammatory bowel disease, immunodeficiency, hypertension, type-2-diabetes, obesity, and cancer. This review outlines current knowledge from in vitro and in vivo studies concerning the potential therapeutic application of seaweed-derived polysaccharides, polyphenols and peptides to modulate the gut microbiota through diet. Polysaccharides such as fucoidan, laminarin, alginate, ulvan and porphyran are unique to seaweeds. Several studies have shown their potential to act as prebiotics and to positively modulate the gut microbiota. Prebiotics enhance bacterial populations and often their production of short chain fatty acids, which are the energy source for gastrointestinal epithelial cells, provide protection against pathogens, influence immunomodulation, and induce apoptosis of colon cancer cells. The oral bioaccessibility and bioavailability of seaweed components is also discussed, including the advantages and limitations of static and dynamic in vitro gastrointestinal models versus ex vivo and in vivo methods. Seaweed bioactives show potential for use in prevention and, in some instances, treatment of human disease. However, it is also necessary to confirm these potential, therapeutic effects in large-scale clinical trials. Where possible, we have cited information concerning these trials.

Potential benefits of dietary seaweeds as protection against COVID-19

The coronavirus disease 2019 (COVID-19) pandemic in Japan is not as disastrous as it is in other Western countries, possibly because of certain lifestyle factors. One such factor might be the seaweed-rich diet commonly consumed in Japan. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which binds to angiotensin-converting enzyme 2 (ACE2) on the cell surface and downregulates ACE2, likely elevating the ratio of angiotensin-converting enzyme (ACE) to ACE2. The overreaction of the immune system, combined with the cytokine storm and ACE dominance, is purported to cause the condition of COVID-19 patients to deteriorate rapidly. Dietary seaweeds contain numerous components, including ACE inhibitory peptides, soluble dietary fibers (eg, fucoidan, porphyran), omega-3 fatty acids, fucoxanthin, fucosterol, vitamins D₃ and B₁₂, and phlorotannins. These components exert antioxidant, anti-inflammatory, and antiviral effects directly as well as indirectly through prebiotic effects. It is possible that ACE inhibitory components could minimize the ACE dominance caused by SARS-CoV-2 infection. Thus, dietary seaweeds might confer protection against COVID-19 through multiple mechanisms. Overconsumption of seaweeds should be avoided, however, as seaweeds contain high levels of iodine.

Twelve weeks' treatment with a polyphenol-rich seaweed extract increased HDL cholesterol with no change in other biomarkers of chronic disease risk in overweight adults: A placebo-controlled randomized trial

Cardiovascular diseases (CVD) are the leading global cause of death. Strategies to reduce CVD risk are urgently needed. Polyphenols represent a class of bioactive compounds with potential to moderate biochemical risk factors for CVD (cholesterol, triglycerides, glucose, and inflammation). This double-blind, placebo-controlled, randomized parallel-groups trial investigated the effect of a polyphenol-rich seaweed (Fucus vesiculosus) extract on biochemical markers of CVD risk. Thirty-four overweight and obese adults (21 female, 13 male) with elevated low-density lipoprotein cholesterol (>2.0 mmol/L) were randomized to either the seaweed extract (2000 mg/d) or placebo for twelve weeks. Fasting blood samples were collected at baseline, week six and week twelve to assess biochemical markers. Tests of cognitive performance and mood were performed at baseline, week six and week twelve. A 9.5% (-2.3, 12.9) increase in high-density lipoprotein (HDL) cholesterol was identified following the seaweed extract (baseline: mean (SD) 1.28 (0.23) mmol/L, week 12: 1.35 (0.24) mmol/L) which was different to placebo (baseline: 1.38 (0.54) mmol/L, week 12: 1.35 (0.59) mmol/L) (P=.045). No changes were identified in low-density lipoprotein cholesterol, total cholesterol, triglycerides, glucose, insulin, interleukin (IL)-2, IL-6, IL-8, IL-10, or tumour necrosis factor-alpha levels in the blood, or in cognitive performance or mood between the treatment and placebo groups. Despite the small increase observed in HDL cholesterol, the polyphenol-rich seaweed extract did not change CVD risk factors in adults with high fasting lipids. A larger sample size would be required to confirm the clinical relevance of the changes in HDL cholesterol.

The potential of marine resources for retinal diseases: a systematic review of the molecular mechanisms

We rely on vision more than on any other sense to obtain information about our environment. Hence, the loss or even impairment of vision profoundly affects our quality of life. Diet or food components have already demonstrated beneficial effects on the development of retinal diseases. Recently, there has been a growing interest in resources from marine animals and plants for the prevention of retinal diseases through nutrition. Especially fish intake and omega-3 fatty acids have already led to promising results, including associations with a reduced incidence of retinal diseases. However, the underlying molecular mechanisms are insufficiently explained. The aim of this review was to summarize the known mechanistic effects of marine resources on the pathophysiological processes in retinal diseases. We performed a systematic literature review following the PRISMA guidelines and identified 107 studies investigating marine resources in the context of retinal diseases. Of these, 46 studies described the underlying mechanisms including anti-inflammatory, antioxidant, antiangiogenic/vasoprotective, cytoprotective, metabolic, and retinal function effects, which we critically summarize. We further discuss perspectives on the use of marine resources for human nutrition to prevent retinal diseases with a particular focus on regulatory aspects, health claims, safety, and bioavailability.

Dieckol isolated from a brown alga, Eisenia nipponica, suppresses ear swelling from allergic inflammation in mouse

We previously found a lipophilic fraction of the methanol/chloroform extract of a brown alga, Eisenia nipponica, that had an antiallergic effect in a murine ear swelling test. In this study, we purified the active component from the lipophilic fraction using high performance liquid chromatography and analyzed the mass and nuclear magnetic resonance spectra. This uncovered the phlorotannin dieckol, which exhibited antiallergic effects in an ear swelling test using mice sensitized by arachidonic acid, 12-O-tetradecanoylphorbol-13-acetate, and oxazolone. Mechanistic investigations indicated that dieckol suppressed degranulation, chemical mediator release, and the expression of mRNA such as cyclooxygenase-2, interleukin-6, and tumor necrosis factor-α in rat basophilic leukemia-2H3 cells. In summary, we isolated dieckol from E. nipponica and demonstrated its antiallergic mechanisms. PRACTICAL APPLICATIONS: As the incidence of allergies increases worldwide, so too does the demand for food components with antiallergic and anti-inflammatory properties. Given this trend, we focused on a brown alga that displays a variety of bioactivities. Here, we have isolated dieckol from the antiallergic lipophilic fraction of E. nipponica and found that it possesses diverse physiological activities that may prevent lifestyle-related diseases. Consequently, dieckol or the alga containing this phlorotannin could be used as a health food ingredient to combat not only allergies, but also variety of disorders including the undesirable effects of aging.

Effects of brown seaweed polyphenols, a class of phlorotannins, on metabolic disorders via regulation of fat function

It is well known that fat dysfunction is the main driver of development of metabolic disorders. Changes in diet and lifestyle are particularly important to reverse the current global rise in obesity-related metabolic disorders. Seaweed has been consumed for thousands of years, and it is rich in bioactive compounds, especially unique polyphenols. The aim of the present review is to summarize the effects of different seaweed polyphenols on fat function in metabolic disorders and the related mechanisms. Seaweed polyphenols activate white adipose tissue to "brown" or "beige" adipose tissue to enhance energy consumption. In addition, the amelioration of fat factor imbalance and inflammatory response is also considered as an important reason for the regulation of lipid function with seaweed polyphenols. The present review provides an important basis for using seaweed polyphenols as potential dietary supplements to prevent metabolic disorders.

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.

Effects of Low ω6:ω3 Ratio in Sow Diet and Seaweed Supplement in Piglet Diet on Performance, Colostrum and Milk Fatty Acid Profiles, and Oxidative Status

Simple Summary

Feeding maternal animals divergent ratios of omega-6 (ω6) and omega-3 (ω3) fatty acids can change not only their health, physiological condition, and performance but also do the same for their offspring. In swine production, various ω6:ω3 ratios have been tested, but the search for an optimal proportion in the sow diet is still in progress. For piglets, weaning oxidative stress has been alleviated by supplementing with abundant sources of bioactive compounds. In this case, brown seaweed, a rich source of natural antimicrobials and antioxidants, can be a good candidate, but its supplementation in piglet diet is limited. This study explores the hypothesis that feeding a low ω6:ω3 ratio diet to sows during gestation and lactation, together with the supplementation of Ascophyllum nodosum for piglets during the post-weaning period, could benefit piglets’ performance and oxidative status more than the respective single treatment provided to the mother or the piglet. Results showed that the low dietary ω6:ω3 ratio (4:1) and seaweed supplement did not affect the post-weaning piglets’ growth rate and oxidative status. However, a low ω6:ω3 ratio diet alone improved weaning survival rate, suckling piglets’ weight gain, and total ω3 fatty acids in colostrum and milk.

Abstract

The ratio of omega-6 (ω6) to omega-3 (ω3) polyunsaturated fatty acids (PUFAs) in the diet contributes to animal health and performance modulations because they have mostly opposite physiological functions. Increasing ω3 PUFAs content in the maternal diet can stimulate antioxidative capacity in sow and piglets; however, the optimal ratio of ω6 and ω3 PUFAs in the sow diet is still under discussion. Rich sources of bioactive constituents such as brown seaweed are an excellent supplementation to promote animal health and antioxidant status. However, the knowledge of the effects of this compound, specifically in post-weaning piglets, is still limited. Moreover, the combined effect of a low ω6:ω3 PUFAs ratio in sow diet and seaweed supplementation in post-weaning piglets’ diet has never been studied. This research aims to assess the combined effect of a low ω6:ω3 ratio in sow diets and seaweed supplementation in piglet diets on their growth and oxidative status. We also assessed the impact of a low ω6:ω3 ratio in the maternal diet on reproduction, milk fatty acid (FA) profile, and plasma leptin concentration. Two sow diets (n = 8 each) contained either a control ratio (CR, 13:1 during gestation, starting from day 28 (G28) and 10:1 during lactation) or a low ratio (LR, 4:1 from G28 until the end of lactation (L-End)) of ω6:ω3 FA by adding soybean oil or linseed oil, respectively. Reproductive performance was evaluated. Colostrum and milk at lactation day 7 (L7) and L-End were collected to analyze FA profile. Plasma was collected at G28, G79, G108, L7, L14, and L-End for determination of leptin and oxidative status. At weaning, 20 male piglets were selected per sow group to form 4 diet treatments (n = 10 each), which were supplemented with or without 4 g/kg seaweed. Recording of growth performance and collection of blood were performed at days 0, 7, 15, and 21 of post-weaning for oxidative status. LR diet increased (p < 0.05) the survival rate of piglets at weaning, and individual and litter weight gains. Colostrum and milk at L7 and L-End had lower (p < 0.05) ω6:ω3 ratio in LR sows. Interaction between dietary treatments on sows and piglets was revealed for all examined growth parameters at most time points (p < 0.05). LR diet did not affect plasma leptin levels and oxidative status. These findings suggest that the seaweed supplement during post-weaning could not improve growth rate and oxidative status of piglets born from mothers receiving a low dietary ω6:ω3 ratio (4:1) during gestation and lactation. However, this low ratio was beneficial for weaning survival rate, sucking piglets’ weight gain, and ω3 enrichment in colostrum and milk.