Fucoidan from Laminaria japonica Ameliorates Type 2 Diabetes Mellitus in Association with Modulation of Gut Microbiota and Metabolites in Streptozocin-Treated Mice

Exploring the potential of Fucoidan from Laminaria japonica: A comprehensive review of its biological activities and benefits for human

Laminaria japonica (L. japonica), a widely cultivated marine macroalga, has gained substantial attention in human nutrition due to its rich composition of carbohydrates, essential minerals, and vitamins. As one of the primary polysaccharides in L. japonica, fucoidan has demonstrated notable biological activities, including anti-inflammatory, antioxidant, antimicrobial, antiviral, cardiovascular protective effects, modulation of gut microbiota, and improvement of metabolic disorders, thereby holding significant potential in food and healthcare applications. Despite these recognized benefits, systematic reviews addressing the extraction and purification methodologies, structural elucidation, compositional analysis, and associated bioactivities of L. japonica-derived fucoidan remain limited. This review comprehensively examines current advancements in fucoidan extraction and purification techniques, discusses its structural characterization, and synthesizes recent findings on its multifaceted biological activities to explore its potential and significance in human health.

Medicinal and edible homologous poly/oligo-saccharides: Structural features, effect on intestinal flora and preventing and treating type 2 diabetes, and their applications: A review

Type 2 diabetes mellitus (T2DM) is the third most common chronic metabolic disorder worldwide and seriously dangerous. Novel therapeutics are sought due to the paucity of safe and effective metabolic disorder-related diabetes medicines. Intestinal flora impacts glucose and lipid balance, making it a unique T2DM therapeutic target. Due to gut fermentation, poly/oligo-saccharides are highly beneficial prebiotic carbohydrates for intestinal health. Moreover, supplementation with naturally occurring medicinal and edible homologous traditional Chinese medicines (MEHTCM) poly/oligo-saccharides has significant antidiabetic effects with few side effects. Now, a comprehensive review of research developments of MEHTCM poly/oligo-saccharides was presented to explore their prospects. We outlined the structural characteristics, structure classification, and structure-activity relationships. Notably, structure-activity relationships illustrated that molecular weight, monosaccharide composition, and glycosidic bond type could influence the hypoglycemic activity and prebiotic effect of MEHTCM poly/oligo-saccharides. Additionally, the review systematically summarized the effect and potential mechanism of MEHTCM poly/oligo-saccharide on T2DM, focusing on gut microbiota. The potential applications in formulations for special medical purposes, common food, health care product, agriculture and other fields have also been summarized. This review emphasizes MEHTCM poly/oligo-saccharides' potential as prebiotics for T2DM treatment. This information provides new insights and a theoretical foundation for MEHTCM poly/oligo-saccharide nutritional and medicinal research.

Laminaria japonica Polysaccharide Regulates Fatty Hepatosis Through Bile Acids and Gut Microbiota in Diabetes Rat

In this study, we examined the effect of Laminaria japonica polysaccharide (fucoidan) on the regulation of lipid metabolism. A rat model of diabetes mellitus (DM) was established by a high-sugar and high-fat diet combined with streptozotocin. Changes in the rats' body weight and blood glucose level during the experiment were recorded. Before the end of the experiment, an automatic biochemical analyzer was used to detect the fasting blood glucose (FBG), lipid content in serum, and insulin content, and calculate the insulin resistance index. Oil red O staining was used to detect lipid deposition in the liver. H&E staining, Masson staining, and PASM staining were used to observe the pathological structural changes in the liver. 16 s RNA sequencing and targeted metabolomics were used to detect intestinal microbiota and bile acid content. The results showed that fucoidan was able to inhibit weight loss in the DM rats and reduce the content of triglycerides (TG), cholesterol (TC), and low-density lipoprotein (LDL-C) in serum. Oil red O staining showed a decrease in liver fat accumulation after fucoidan treatment. 16 s RNA sequencing demonstrated that fucoidan increased the abundance of Bacteroidia, Campylobacteria, Clostridia, Gammaproteobacteria, Negativicutes, and Verrucomicrobi. Fucoidan also increased the secretion of secondary bile acids (Nor-DCA, TLCA, β-UDCA) and alleviated lipid metabolism disorders. The expression of α-SMA was inhibited by fucoidan, whereas the expression of FXR and TGR5 was promoted. Fucoidan shows good activity in regulating lipid metabolism by regulating the expression of FXR and TGR5 and acting on the intestinal flora-bile acid axis.

Antiviral activity of a polysaccharide from Sargassum fusiforme against respiratory syncytial virus

This experiment examined the antiviral activity of polysaccharides from Sargassum fusiforme against respiratory syncytial virus (RSV) in vitro, including their mechanism of action and preliminary structural analysis. Four polysaccharides (SFP1, SFP2, SFP3, and SFP4) were purified from Sargassum fusiforme using a DEAE-52 cellulose column and an NW Super 150 gel column. CCK-8 and western blot were utilized to study the antiviral activities and mechanisms of the polysaccharides. Preliminary structural analysis was conducted using HPLC and NMR techniques. The findings suggest that SFP4 (120 kD) is an acidic chemical compound composed of 88.8 % total sugars, 0.13 % proteins, 10.8 % glucuronidic acids, and 21.1 % sulfates. It contains at least ten monosaccharides, primarily mannuronic acid and fucose. Among the four polysaccharides, SFP4 had the highest anti-RSV activity, with a therapeutic index (TI) exceeding 139. SFP4 exhibited noteworthy antiviral efficacy in both upper and lower respiratory cells that were infected, especially when administered as a prophylactic treatment 2 h in advance. Furthermore, SFP4 showed a dose-dependent antiviral effect, with the highest therapeutic index (TI > 320) observed at a concentration of 7.81 μg·mL-1 during the prophylactic phase. It was speculated that SFP4's antiviral effect is due to its ability to inhibit the attachment of G-proteins to cells.

Polysaccharides in Medicinal and Food Homologous Plants regulate intestinal flora to improve type 2 diabetes: Systematic review

BACKGROUND

Medicinal and food homologous plants (MFHPs) which can improve Type 2 Diabetes Mellitus (T2DM) draw significant attention among the public due to their low toxicity and more safety. Polysaccharides, one of the various active components of MFHPs, are recognized as effective modulators of the intestinal flora. By altering the composition of intestinal flora and affecting their metabolic products, polysaccharides can improve T2DM, making them a central focus of anti-diabetic research.

PURPOSE

The purpose of this study is to systematically review the mechanism by which polysaccharides from MFHPs (MFHPPs) regulate the composition of intestinal flora and its metabolic products to improve T2DM.

METHODS

This study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and conducts a comprehensive search on the PubMed, Web of Science and Embase databases. All experimental articles published up to March 4, 2024, are included in the search.

RESULTS

Among the 5733 articles reviewed, 29 were selected, covering 22 different MFHPs. MFHPPs can improve T2DM, particularly in lowering blood glucose levels, with consistent results. MFHPPs can regulate the diversity of intestinal flora in T2DM animal models, primarily affecting four phyla: decreasing Firmicutes and Proteobacteria while increasing Bacteroidetes and Actinobacteriota. At the genus level, the improvement of T2DM by MFHPPs is associated with the modulation of 12 key genera: Allobaculum, Akkermansia, Bifidobacterium, Lactobacillus, Helicobacter, Halomonas, Olsenella, Oscillospira, Shigella, Escherichia-Shigella, Romboutsia and Bacteroides. At the molecular level, MFHPPs primarily act by modulating the intestinal flora to increase short-chain fatty acid levels, promote the secretion of glucagon-like peptide-1, influence the IGF1/PI3K/AKT signaling pathway, or the PI3K/AKT/GSK-3β pathway, to lower blood glucose levels. They may also improve T2DM by working in glucose metabolism through the "microbiota-gut-organ" axis. MFHPPs can also alleviate T2DM by mitigating inflammation and oxidative stress: MFHPPs regulate intestinal flora to reduce lipopolysaccharide "leakage" and enhance intestinal mucosal permeability to tackle the inflammation associated with T2DM; MFHPPs enhance the expression of oxidative stress-related enzymes to alleviate oxidative stress and improve T2DM. Lastly, from a metabolic pathway perspective, MFHPPs are primarily involved in the metabolism of amino acids and their derivatives, carbohydrate metabolism and glutathione metabolism.

CONCLUSION

MFHPPs can improve T2DM by enhancing the composition of intestinal flora, regulating its metabolic products to promote insulin secretion, inhibiting glucagon-like peptide secretion, facilitating glycogen synthesis, reducing inflammation levels and alleviating oxidative stress. Furthermore, MFHPPs demonstrate potential protective effects on critical organs such as the pancreas, liver, kidneys and heart. Therefore, MFHPPs demonstrate significant clinical potential. However, most studies can only indicate the potential of MFHPPs intervention in improving T2DM through the intestinal flora. The causality between MFHPPs regulating the intestinal flora and T2DM requires further investigation.

Lipid- and glucose-lowering effects of Rhamnan sulphate from Monostroma nitidum with altered gut microbiota in mice

Rhamnan sulphate (RS) is a sulphated polysaccharide found in green algae such as Monostroma nitidum that exhibits various biological functions, including anticoagulant, antitumour, antiviral, and anti-obesity properties. In our previous clinical trial, we demonstrated that RS intake improves constipation. However, no specific bacteria showed a significant (p < .05) change. Notably, these results were obtained after a short RS inoculation period of only 2 weeks. In the present study, to evaluate the long-term effects of RS on the gut microbiota, we orally administered RS to BALB/c mice for 11 weeks, analyzed their blood biochemical data, and performed 16s rRNA-sequencing. Oral administration of RS increased body weight with increased food intake, whereas plasma total cholesterol and fasting plasma glucose levels decreased. RS-fed mice showed lower fasting insulin levels (p < .1) and decreased homeostatic model assessment for insulin resistance (HOMA-IR, p < .0001), suggesting that RS improved insulin resistance. In the feces of mice, the amounts of acetic and propionic acids increased. In the gut microbiota, predictive metagenomic profiling using the phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt2) revealed functional alterations in Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways in RS-fed mice. Corresponding to the blood glucose-lowering effect, the glycolysis and tricarboxylic acid (TCA) cycle pathways were activated. In addition, the Firmicutes/Bacteroides (F/B) ratio, which may be associated with various health outcomes, was also reduced. These results suggest that the blood glucose-lowering effect, improvement in insulin resistance, and lipid-lowering effect of RS may be due to changes in the intestinal microbiota.

Exploring the prebiotic potential of hydrolyzed fucoidan fermented in vitro with human fecal inocula: Impact on microbiota and metabolome

Fucoidan is widely applied in food and pharmaceutical industry for the promising bioactivities. Low-molecular weight hydrolyzed fucoidan has gained attention for its beneficial health effects. Here, the modulation on microbiome and metabolome features of fucoidan and its acidolyzed derivatives (HMAF, 1.5-20 kDa; LMAF, <1.5 kDa) were investigated through human fecal cultures. Fucose is the main monosaccharide component in fucoidan and LMAF, while HMAF contains abundant glucuronic acid. LMAF fermentation resulted in the highest production of short-chain fatty acids, with acetate and propionate reaching maximum levels of 13.46 mmol/L and 11.57 mmol/L, respectively. Conversely, HMAF exhibited a maximum butyrate production of 9.28 mmol/L. Both fucoidan and acidolyzed derivatives decreased the abundance of Escherichia-Shigella and Klebsiella in human fecal cultures. Fucoidan and HMAF prefer to improve the abundance of Bacteroides. However, LMAF showed positive influence on Bifidobacterium, Lactobacillus, and Megamonas. Untargeted metabolome indicated that fucoidan and its derivatives mainly altered the metabolic level of lipids, indole, and their derivatives, with fucoidan and HMAF promoting higher level of indole-3-propionic acid and indole-3-carboxaldehyde compared to LMAF. Considering the chemical structural differences, this study suggested that hydrolyzed fucoidan can provide potential therapeutic applications for targeted regulation of microbial communities.

Edible traditional Chinese medicines improve type 2 diabetes by modulating gut microbiotal metabolites

Type 2 diabetes mellitus (T2DM) is a metabolic disorder with intricate pathogenic mechanisms. Despite the availability of various oral medications for controlling the condition, reports of poor glycemic control in type 2 diabetes persist, possibly involving unknown pathogenic mechanisms. In recent years, the gut microbiota have emerged as a highly promising target for T2DM treatment, with the metabolites produced by gut microbiota serving as crucial intermediaries connecting gut microbiota and strongly related to T2DM. Increasingly, traditional Chinese medicine is being considered to target the gut microbiota for T2DM treatment, and many of them are edible. In studies conducted on animal models, edible traditional Chinese medicine have been shown to primarily alter three significant gut microbiotal metabolites: short-chain fatty acids, bile acids, and branched-chain amino acids. These metabolites play crucial roles in alleviating T2DM by improving glucose metabolism and reducing inflammation. This review primarily summarizes twelve edible traditional Chinese medicines that improve T2DM by modulating the aforementioned three gut microbiotal metabolites, along with potential underlying molecular mechanisms, and also incorporation of edible traditional Chinese medicines into the diets of T2DM patients and combined use with probiotics for treating T2DM are discussed.

Metabolomics and Biomarkers for Paroxysmal and Persistent Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common type of arrhythmia worldwide and is associated with serious complications. This study investigated the metabolic biomarkers associated with AF and the differences in metabolomics and associated metabolic biomarkers between paroxysmal AF (AFPA) and persistent AF.

METHODS AND RESULTS

Plasma samples were prospectively collected from patients with AF and patients in sinus rhythm with negative coronary angiography. The patients were divided into 3 groups: AFPA, persistent AF, and sinus rhythm (N=54). Metabolomics (n=36) using ultra-high-performance liquid chromatography mass spectrometry was used to detect differential metabolites that were validated in a new cohort (n=18). The validated metabolites from the validation phase were further analyzed by receiver operating characteristic. Among the 36 differential metabolites detected by omics assay, 4 were successfully validated with area under the curve >0.8 (P<0.05). Bioinformatics analysis confirmed the enrichment pathways of unsaturated fatty acid biosynthesis, glyoxylate and dicarboxylate metabolism, and carbon metabolism. Arachidonic acid was a potential biomarker of AFPA, glycolic acid and L-serine were biomarkers of AFPA and persistent AF, and palmitelaidic acid was a biomarker of AFPA.

CONCLUSIONS

In this metabolomics study, we detected 36 differential metabolites in AF, and 4 were validated with high sensitivity and specificity. These differential metabolites are potential biomarkers for diagnosis and monitoring of disease course. This study therefore provides new insights into the precision diagnosis and management of AF.

Recent advances in medicinal and edible homologous plant polysaccharides: Preparation, structure and prevention and treatment of diabetes

Medicinal and edible homologs (MEHs) can be used in medicine and food. The National Health Commission announced that a total of 103 kinds of medicinal and edible homologous plants (MEHPs) would be available by were available in 2023. Diabetes mellitus (DM) has become the third most common chronic metabolic disease that seriously threatens human health worldwide. Polysaccharides, the main component isolated from MEHPs, have significant antidiabetic effects with few side effects. Based on a literature search, this paper summarizes the preparation methods, structural characterization, and antidiabetic functions and mechanisms of MEHPs polysaccharides (MEHPPs). Specifically, MEHPPs mainly regulate PI3K/Akt, AMPK, cAMP/PKA, Nrf2/Keap1, NF-κB, MAPK and other signaling pathways to promote insulin secretion and release, improve glycolipid metabolism, inhibit the inflammatory response, decrease oxidative stress and regulate intestinal flora. Among them, 16 kinds of MEHPPs were found to have obvious anti-diabetic effects. This article reviews the prevention and treatment of diabetes and its complications by MEHPPs and provides a basis for the development of safe and effective MEHPP-derived health products and new drugs to prevent and treat diabetes.

Correction: Zhang et al. Fucoidan from Laminaria japonica Ameliorates Type 2 Diabetes Mellitus in Association with Modulation of Gut Microbiota and Metabolites in Streptozocin-Treated Mice. Foods 2023, 12, 33

In the original publication, there was a mistake in Figure 3 as published [...].

Fucoidan from Sargassum wightii reduces oxidative stress through upregulating Nrf2/HO-1 signaling pathway in alloxan-induced diabetic cardiomyopathy rats

BACKGROUND

Diabetic cardiomyopathy (DCM) is a form of cardiac dysfunction caused by diabetes, increasing heart failure and death. Studies shown that hyperglycemia-induced oxidative stress significantly affects heart structure and functional changes during diabetic cardiomyopathy. Fucoidans are sulfated polysaccharide derived from naturally available seaweeds and reported for various biological functions such as antioxidant, anti-diabetic, and anti-inflammatory. However, the therapeutic potential of Indian seaweeds against DCM remains largely unexplored. Therefore, the current study aimed to work on the cardioprotective effect of extracted fucoidan from Sargassum wightii (SwF) in alloxan-induced DCM.

METHODS AND RESULTS

Diabetes (DM) was induced with alloxan monohydrate (150 mg/kg-1) dissolved in Nacl (0.9%) overnight-fasted rats. Group III, IV rats were DM induced, followed by treated with SwF (150 mg/kg-1) and (300 mg/kg-1). Group V and VI were non-diabetic rats and received SwF (150 mg/kg-1) and (300 mg/kg-1). SwF reduced classical progressive DM complications such as hyperglycemia, polydipsia, polyphagia, and polyurea in alloxan-induced diabetic rats. Biochemical analysis showed that SwF decreased blood glucose, cardiac markers enzymes, and lipid peroxidation levels compared to diabetic rats. SwF administration significantly increased Nrf2, HO-1, SOD, Catalase, and NQO1 gene expression. In addition, SwF-treated rats showed reduced heart tissue damage with increased Nrf2 and HO-1 protein expression.

CONCLUSION

The current research concludes that targeting oxidative stress with SwF provided an effective role in the prevention of DCM. Thus, fucoidan could be used to develop functional food ingredients for DCM.

Fucoidan derived from Sargassum pallidum alleviates metabolism disorders associated with improvement of cardiac injury and oxidative stress in diabetic mice

Type 2 diabetes mellitus (T2DM) and its complications have become a serious global health epidemic. Cardiovascular complications have considered as a major cause of high mortality in diabetic patients. Fucoidans from brown algae have diverse medicinal activities, however, few studies reported pharmacological activity of Sargassum. pallidum fucoidan (Sp-Fuc). Therefore, the aim of this study was to investigate the effects of Sp-Fuc on diabetic symptoms and cardiac injury in spontaneous diabetic db/db mice. SP-Fuc at 200 mg/(kg/d) was administered intragastrically to db/db mice for 8 weeks, the effects on hyperlipidemia, hyperglycemia, insulin resistance, and cardiac damage, as well as oxidative stress, inflammation, Nrf2/ARE, and NF-κB signaling pathways, were investigated. Our data demonstrated that Sp-Fuc significantly (p < 0.05) decreased body weights, hyperlipidemia, and hyperglycemia in db/db mice, along with improved insulin sensitivity. Additionally, Sp-Fuc significantly (p < 0.05) alleviated cardiac dysfunction and pathological morphology of cardiac tissue. Sp-Fuc also significantly (p < 0.05) decreased lipid peroxidation, increased antioxidant function, as well as reduced cardiac inflammation, possibly through Nrf2/ARE and NF-κB signaling. Sp-Fuc can ameliorate the metabolism disorders of glucose and lipid in diabetic mice by activating Nrf2/ARE antioxidant signaling, simultaneously reducing cardiac redox imbalance and inflammatory damage. The present findings provide a perspective on the therapy strategy for T2DM and its complications.

Therapeutic Potential of Polyphenols and Other Micronutrients of Marine Origin

Polyphenols are compounds found in various plants and foods, known for their antioxidant and anti-inflammatory properties. Recently, researchers have been exploring the therapeutic potential of marine polyphenols and other minor nutrients that are found in algae, fish and crustaceans. These compounds have unique chemical structures and exhibit diverse biological properties, including anti-inflammatory, antioxidant, antimicrobial and antitumor action. Due to these properties, marine polyphenols are being investigated as possible therapeutic agents for the treatment of a wide variety of conditions, such as cardiovascular disease, diabetes, neurodegenerative diseases and cancer. This review focuses on the therapeutic potential of marine polyphenols and their applications in human health, and also, in marine phenolic classes, the extraction methods, purification techniques and future applications of marine phenolic compounds.