Fucoidan alleviates high sucrose-induced metabolic disorders and enhances intestinal homeostasis through modulation of Notch signaling.

INTRODUCTION: The therapeutic potential of fucoidan (FUC), a natural polysaccharide, in metabolic disorders is recognized, yet its underlying mechanisms remain unclear. METHODS: We conducted investigations into the therapeutic mechanisms of FUC sourced from Sargassum fulvellum concerning metabolic disorders induced by a high-sucrose diet (HSD), employing Drosophila melanogaster and mice models. Drosophila larvae were subjected to HSD exposure to monitor growth inhibition, reduced pupation, and developmental delays. Additionally, we examined the impact of FUC on growth- and development-related hormones in Drosophila. Furthermore, we assessed the modulation of larval intestinal homeostasis by FUC, focusing on the regulation of Notch signaling. In mice, we evaluated the effects of FUC on HSD-induced impairments in intestinal epithelial barrier integrity and gut hormone secretion. RESULTS: FUC supplementation significantly enhanced pupal weight in Drosophila larvae and effectively countered HSD-induced elevation of glucose and triglyceride levels. It notably influenced the expression of growth- and development-related hormones, particularly augmenting insulin-like peptides production while mitigating larval growth retardation. FUC also modulated larval intestinal homeostasis by negatively regulating Notch signaling, thereby protecting against HSD-induced metabolic stress. In mice, FUC ameliorated HSD-induced impairments in ileum epithelial barrier integrity and gut hormone secretion. CONCLUSIONS: Our findings demonstrate the multifaceted therapeutic effects of FUC in mitigating metabolic disorders and maintaining intestinal health. FUC holds promise as a therapeutic agent, with its effects attributed partly to the sulfate group and its ability to regulate Notch signaling, emphasizing its potential for addressing metabolic disorders.

Quantitative proteomics reveals the neurotoxicity of trimethyltin chloride on mitochondria in the hippocampus of mice.

Trimethyltin chloride (TMT) is a potent neurotoxin widely used as a constituent of polyvinyl chloride plastic in the industrial and agricultural fields. However, the underlying mechanisms by which TMT leads to neurotoxicity remain elusive. In the present study, we constructed a dose and time dependent neurotoxic mouse model of TMT exposure to explore the molecular mechanisms involved in TMT-induced neurological damage. Based on this model, the cognitive ability of TMT exposed mice was assessed by the Morris water maze test and a passive avoidance task. The ultrastructure of hippocampus was analyzed by the transmission electron microscope. Subsequently, proteomics integrated with bioinformatics and experimental verification were employed to reveal potential mechanisms of TMT-induced neurotoxicity. Gene ontology (GO) and pathway enrichment analysis were done by using Metascape and GeneCards database respectively. Our results demonstrated that TMT-exposed mice exhibited cognitive disorder, and mitochondrial respiratory chain abnormality of the hippocampus. Proteomics data showed that a total of 7303 proteins were identified in hippocampus of mice of which 224 ones displayed a 1.5-fold increase or decrease in TMT exposed mice compared with controls. Further analysis indicated that these proteins were mainly involved in tricarboxylic acid (TCA) cycle and respiratory electron transport, proteasome degradation, and multiple metabolic pathways as well as inflammatory signaling pathways. Some proteins, including succinate-CoA ligase subunit (Suclg1), NADH dehydrogenase subunit 5 (Nd5), NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 4-like 2 (Ndufa4l2) and cytochrome c oxidase assembly factor 7 (Coa7), which were closely related to mitochondrial respiratory electron transport, showed TMT dose and time dependent changes in the hippocampus of mice. Moreover, apoptotic molecules Bax and cleaved caspase-3 were up-regulated, while anti-apoptotic Bcl-2 was down-regulated compared with controls. In conclusion, our findings suggest that impairment of mitochondrial respiratory chain transport and promotion of apoptosis are the potential mechanisms of TMT induced hippocampus toxicity in mice.

Structural characterization and antagonistic effect against P-selectin-mediated function of SFF-32, a fucoidan fraction from Sargassum fusiforme.

ETHNOPHARMACOLOGICAL RELEVANCE: Sargassum fusiforme (Harvey) Setchell, or Haizao, has been used in traditional Chinese medicine (TCM) since at least the eighth century a.d. S. fusiforme is an essential component of several Chinese formulas, including Haizao Yuhu Decoction, used to treat goiter, and Neixiao Lei Li Wan used to treat scrofuloderma. The pharmacological efficacy of S. fusiforme may be related to its anti-inflammatory effect. AIM OF THE STUDY: To determine the structural characteristics of SFF-32, a fucoidan fraction from S. fusiforme, and its antagonistic effect against P-selectin mediated function. MATERIALS AND METHODS: The primary structure of SFF-32 was determined using methylation/GC-MS and NMR analysis. Surface morphology and solution conformation of SFF-32 were determined by scanning electron microscopy (SEM), Congo red test, and circular dichroic (CD) chromatography, respectively. The inhibitory effects of SFF-32 against the binding of P-selectin to HL-60 cells were evaluated using flow cytometry, static adhesion assay, and parallel-plate flow chamber assay. Furthermore, the blocking effect of SFF-32 on the interaction between P-selectin and PSGL-1 was evaluated using an in vitro protein binding assay. RESULTS: The main linkage types of SFF-32 were proven to →[3)-α-l-Fucp-(1→3,4)-α-l-Fucp-(1]2→[4)-ß-d-Manp-(1→3)-d-GlcAp-(1]2→4)-ß-d-Manp-(1→3)-ß-d-Glcp-(1→4)-ß-d-Manp-(1→2,3)-ß-d-Galp-(1→4)-ß-d-Manp-(1→[4)-α-l-Rhap-(1]3→. The sulfated unit or terminal xylose residues were attached to the backbone through the C-3 of some fucose residues and terminal xylose residues were attached to C-3 of galactose residues. Moreover, SFF-32 disrupted P-selectin-mediated cell adhesion and rolling as well as blocked the interaction between P-selectin and its physiological ligand PSGL-1 in a dose-dependent manner. CONCLUSIONS: Blocking the binding between P-selectin and PSGL-1 is the possible underlying mechanism by which SFF-32 inhibits P-selectin-mediated function, which demonstrated that SFF-32 may be a potential anti-inflammatory lead compound.

Ethanol extract of Sargarsum fusiforme alleviates HFD/STZ-induced hyperglycemia in association with modulation of gut microbiota and intestinal metabolites in type 2 diabetic mice.

Type 2 diabetes mellitus (T2DM) is considered a rapidly growing chronic disease that threatens human health worldwide. Extracts of various seaweeds have been shown to have anti-diabetic activity. Sargarsum fusiforme, an edible brown seaweed, has been shown to possess anti-inflammatory, anti-diabetic and anti-obesity activities. In this study, we investigated the beneficial effect of an ethanol extract of S. fusiforme (EE) on type 2 diabetes in mice induced with high-fat diet (HFD) and streptozotocin (STZ). Administering EE to the diabetic mice significantly reduced food intake, water intake and fasting blood glucose (FBG), while improving glucose tolerance, lipid profile and ameliorating hepatic oxidative stress. Furthermore, these animals also exhibited significantly diminished epididymal fat deposition, as well as less pathological changes in the heart and liver tissues, while displaying some highly enriched benign gut bacteria (e.g., Intestinimonas, Oscillibacter, Lachnoclostridium, unidentified_Lachnospiraceae, Roseburia and Anaerotruncus) and a lower abundance of bacteria associated with diabetes or other metabolic diseases (e.g., Enterorhabdus and Romboutsia). Metabolomic analysis revealed reduced levels of branched-chain amino acids (BCAA), such as l-valine and l-isoleucine, aromatic amino acids (AAA), such as l-tyrosine and l-phenylalanine, and increased levels of 4-hydroxyphenylacetic acid (4-HPA) in the gut content, suggesting that EE may impact T2DM through modulation of these compounds in the gut of the animals. Taken together, the results implied that S. fusiforme may contain valuable active components other than polysaccharides that have potential benefit in alleviating T2DM.

Sargassum fusiforme Alginate Relieves Hyperglycemia and Modulates Intestinal Microbiota and Metabolites in Type 2 Diabetic Mice.

Sargassum fusiforme alginate (SF-Alg) possess many pharmacological activities, including hypoglycemic and hypolipidemic. However, the hypoglycemic mechanisms of SF-Alg remain unclear due to its low bioavailability. In this study, we evaluated the therapeutic effect of SF-Alg on high-fat diet (HFD)/streptozotocin (STZ)-induced type 2 diabetes (T2D) mice. SF-Alg intervention was found to significantly reduce fasting blood glucose (FBG), triglycerides (TG), and total cholesterol (TC), while increasing high-density lipoprotein cholesterol (HDL-c) and improving glucose tolerance. In addition, administrating SF-Alg to diabetic mice moderately attenuated pathological changes in adipose, hepatic, and heart tissues as well as skeletal muscle, and diminished oxidative stress. To probe the underlying mechanisms, we further analyzed the gut microbiota using 16S rRNA amplicon sequencing, as well as metabolites by non-targeted metabolomics. Here, SF-Alg significantly increased some benign bacteria (Lactobacillus, Bacteroides, Akkermansia Alloprevotella, Weissella and Enterorhabdus), and significantly decreased harmful bacteria (Turicibacter and Helicobacter). Meanwhile, SF-Alg dramatically decreased branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) in the colon of T2D mice, suggesting a positive benefit of SF-Alg as an adjvant agent for T2D.

Sargassum fusiforme fucoidan modifies gut microbiota and intestinal metabolites during alleviation of hyperglycemia in type 2 diabetic mice.

Type 2 diabetic mellitus (T2DM) is a complicated metabolic disorder that is now considered as a major global public health problem. Fucoidan exhibits diverse biological activities, especially prevention of metabolic diseases. In this regard, we herein aimed to reveal the beneficial effect of Sargassum fusiforme fucoidan (SFF) on high-fat diet (HFD) and streptozotocin (STZ) induced T2DM mice. We noted that on the one hand, SFF significantly decreased fasting blood glucose, diet and water intake, and hyperlipidemia, while on the other hand, it improved glucose tolerance. Furthermore, SFF reduced epididymal fat deposition, attenuated the pathological changes in heart and liver tissues, and decreased oxidative stress in diabetic mice. To explore the underlying mechanisms of these ameliorative effects, the gut microbiota was analyzed. Notably, SFF highly enriched benign microbes including Bacteroides, Faecalibacterium and Blautia, as well as increased levels of (R)-carnitine and choline in the colon of diabetic mice. This may be a potential mechanism for alleviating T2DM, thus implying the benefits of SFF as an adjuvant agent for T2DM treatment. Taken together, this study demonstrated a promising application of fucoidan as one of the adjuvant agents for the management of T2DM in the future.

Sargassum fusiforme Fucoidan Alleviates High-Fat Diet-Induced Obesity and Insulin Resistance Associated with the Improvement of Hepatic Oxidative Stress and Gut Microbiota Profile.

Sargassum fusiforme fucoidan (SFF) exhibits diverse biological activities. Insulin resistance (IR) implicated in type 2 diabetes (T2D) has become an epidemic health issue worldwide. In this study, we investigated whether SFF can improve insulin sensitivity in high-fat diet (HFD)-fed mice. Our present data showed that SFF significantly reduced fasting blood glucose and IR index along with improved glucose tolerance. Impaired phosphorylation of Akt was also restored by SFF. Furthermore, SFF decreased the levels of MDA and 4-HNE-modified protein and increased GSH/GSSG ratio as well as elevated antioxidant enzymes and activated Nrf2 signaling. SFF also increased the abundance and diversity of gut microbiota in the obese mice, as well as improved intestinal integrity and inflammation. Our findings suggested that SFF ameliorated HFD-induced IR through activating the Nrf2 pathway, remodeling gut microbiota, and reducing intestinal inflammation, thus providing a novel perspective into the treatment strategy on metabolic disease.

Gamma-irradiation degraded sulfated polysaccharide from a new red algal strain Pyropia yezoensis Sookwawon 104 with in vitro antiproliferative activity.

Pyropia yezoensis Sookwawon 104 is a newly cultivated strain of red marine algae. The present study aimed to investigate the in vitro antiproliferative activity of sulfated polysaccharide extracted from P. yezoensis Sookwawon 104 (PYSP), as well as that of its low molecular weight (Mw) derivatives. PYSP is a heterogeneous sulfated polysaccharide mainly composed of galactose, glucose and fucose. PYSP was degraded by gamma-irradiation at doses of 20 and 100 kGy to produce two derivatives, named as PYSP-20 and PYSP-100, respectively. Comparison of PYSP, PYSP-20 and PYSP-100 revealed clear differences in their molecular weight (Mw) distributions, and distinct in vitro antiproliferative activities against Hep3B, MDA-MB-231 and HeLa cancer cell lines. PYSP-20 and PYSP-100 exhibited stronger antiproliferative effects than PYSP, suggesting that the reduction in Mw may have increased the in vitro antiproliferative activity. Furthermore, the mRNA expression levels of the antitumor gene P53 and cell cycle-associated genes P21, Cyclin B1 and cyclin dependent kinase 1 (Cdk1) were further analyzed by reverse transcription-quantitative PCR in PYSP-20 and PYSP-100-treated cancer cells. PYSP and its derivatives were shown to inhibit the proliferation of tumor cells by regulating the expression of P53, P21, Cyclin B1 and Cdk1. In conclusion, low-Mw polysaccharide derivatives prepared from P. yezoensis Sookwawon 104 by gamma-irradiation exhibit significant inhibition effects on cancer cell proliferation in vitro and may be a novel source of potential anticancer therapeutic agents.

Different extraction methods bring about distinct physicochemical properties and antioxidant activities of Sargassum fusiforme fucoidans.

Fucoidan is a complex sulfated polysaccharide and an active component found in the cell wall of brown seaweeds. In the present study, fucoidans were obtained from Sargassum fusiforme using different extraction methods, including hot water (prepared fucoidan was named as WSFF), dilute hydrochloric acid (ASFF), and calcium chloride solution (CSFF). The assessments were performed on S. fusiforme fucoidans based on their chemical composition, molecular conformations, and in vitro antioxidant activities. ASFF showed the maximum extraction yield (11.24%), whereas CSFF exhibited the minimum yield (3.94%). The monosaccharide composition of WSFF, ASFF, and CSFF was similar, but the molar ratio of monosaccharide was quite different. Moreover, their molecular weight, Fourier transform infrared (FT-IR) spectrum, surface morphology, uronic acid content and degree of sulfation were distinct. The Congo red test and Circular dichroism spectroscopy analysis displayed some differences in solution conformation of these samples. Furthermore, WSFF, ASFF, and CSFF showed distinct in vitro antioxidant activities evaluated by DPPH and hydroxyl radical scavenging assays. The present study provides scientific evidence on the influences of extraction methods on the physicochemical characteristics, conformation behaviors and antioxidant activities of S. fusiforme fucoidans.

Therapeutic Effects of Fucoidan: A Review on Recent Studies.

Fucoidan is a polysaccharide largely made up of l-fucose and sulfate groups. Fucoidan is favorable worldwide, especially amongst the food and pharmaceutical industry as a consequence of its promising therapeutic effects. Its applaudable biological functions are ascribed to its unique biological structure. Classical bioactivities associated with fucoidan include anti-oxidant, anti-tumor, anti-coagulant, anti-thrombotic, immunoregulatory, anti-viral and anti-inflammatory effects. More recently, a variety of in vitro and in vivo studies have been carried out to further highlight its therapeutic potentials. This review focuses on the progress towards understanding fucoidan and its biological activities, which may be beneficial as a future therapy. Hence, we have summarized in vitro and in vivo studies that were done within the current decade. We expect this review and a variety of others can contribute as a theoretical basis for understanding and inspire further product development of fucoidan.

Antitumor bioactivity of porphyran extracted from Pyropia yezoensis Chonsoo2 on human cancer cell lines.

BACKGROUND: Pyropia yezoensis, rich in porphyran, is a medicine-edible red alga. In the present study, the physicochemical characteristics, conformational states and antitumor activities of a novel porphyran extracted from the high-yield algal strain Pyropia yezoensis Chonsoo2 and its two degraded derivatives by gamma irradiation were investigated. RESULTS: Pyropia yezoensis porphyran is a water-soluble, triple-helical sulfated hetero-galactopyranose, named PYP. PYP was degraded by gamma irradiation at 20 kGy and 50 kGy, giving two low molecular weight derivatives comprising PYP-20 and PYP-50, respectively. PYP with a higher molecular weight has a solution conformation different from PYP-20 and PYP-50. Three porphyrans had no toxicity in normal human liver cells (HL-7702) and showed antitumor effects on Hep3B, HeLa and MDA-MB-231. They had better antitumor against HeLa cells, exhibiting a similar inhibition ratio compared to 5-fluorouracil, with PYP especially exhibiting a higher inhibition ratio than 5-fluorouracil. With respect to HeLa cells, the different antitumor activities might be related to porphyran molecular weight and solution conformation. Furthermore, the HeLa cell cycle was blocked in the G2/M phase after PYP treatment, leading to cell proliferation inhibition. The induction of cell cycle arrest was related to the changes in the expression of p21, p53, Cyclin B1 and cyclin-dependent kinase 1. CONCLUSION: Pyropia yezoensis porphyran, as applied to medicine and functional food, could potentially be used as a non-toxic natural adjuvant in cancer therapy. © 2019 Society of Chemical Industry.

Physicochemical characterization of Sargassum fusiforme fucoidan fractions and their antagonistic effect against P-selectin-mediated cell adhesion.

P-selectin, mediated adhesion between endothelium and neutrophils, is a promising target for the therapeutics of acute inflammatory-related diseases. It is reported that brown algal fucoidans can antagonize P-selectin function. However, the fractionation and physicochemical characterization of Sargassum fusiforme fucoidan, and the screening of fucoidan fractions with P-selectin antagonistic capability have not been investigated. In this study, we isolated and fractionated systematically the S. fusiforme fucoidan by ion-exchange chromatography and size exclusion chromatography to obtain eight fucoidan fractions. Their physicochemical characterization was determined by chemical methods, HPLC and FT-IR. The inhibitory capacity of the fucoidan fractions in P-selectin-mediated leukocyte adhesion was evaluated by static adhesion assay and parallel-plate flow chamber. Results showed that fucoidan fractions possessed distinct physicochemical properties, including total carbohydrate, uronic acid and sulfate contents, molecular weight, and monosaccharide compositions. Among all the fucoidan fractions, SFF-32 and SFF-42 showed better blocking ability against P-selectin-mediated cell adhesion.

Analysis of the stress distribution of the subtalar joint and fusion efficacy after double-screw insertion.

BACKGROUND: Screw fixation is a typical technique for the isolated subtalar joint. However, no consensus has been reached on how to select the most suitable insertion position and direction. This study aims to find the ideal screw insertion and then explore its influence on the clinical efficacy of subtalar fusion by analyzing the effects of different cannulated screw insertions on the stress distribution, anti-rotary strength, and anti-inversion/eversion strength of the subtalar joint. METHODS: In this study, we investigated three cannulated screw insertions for subtalar fusion: screw insertion with the most uniform stress distribution (group A), lateral-medial parallel screw insertion (group B), and traditional longitudinally parallel screw insertion (group C). The effects of these three insertions on the loading stress of the subtalar joint (including stress distribution, anti-inversion/eversion strength, and anti-rotary strength) were comparatively analyzed with the three-dimensional finite element method to screen the ideal screw insertion. Moreover, a prospective study was conducted to analyze the influence of the ideal screw insertion on subtalar fusion, including the fusion rate, fusion time, and clinical efficacy (VAS score, AOFAS score, and complications). RESULTS: Group B was worse than group A with respect to the stress distribution uniformity, but slightly better than group C, and better than both groups A and C in terms of the anti-rotary strength and anti-inversion/eversion strength. The screw insertion based on the most uniform stress distribution is not feasible in surgery. Therefore, the lateral-medial antiparallel screw insertion is the ideal insertion. From January 2012 to June 2016, 48 cases were treated by subtalar fusion with the ideal screw insertion, and then followed up for 30.6 months (12-48 months). The fusion was proved in all 48 cases with a fusion rate of 100% by X-ray or CT scan. The mean time of fusion was 12.8 weeks (12-16 weeks). The VAS score decreased from 6.00 before operation to 1.03 on the last visit (P < 0.05), and the AOFAS score increased from 57.0 to 85.6 (P < 0.05), with a good and excellent rate of 95.8%. CONCLUSIONS: The lateral-medial parallel screw insertion not only demonstrates a good stress distribution profile of the subtalar joint but also has advantages such as easy localization and operation during surgery, as well as a high fusion rate and few complications after surgery. Therefore, it is a safe, accurate, and effective fixation mode that is worthy of being popularized clinically.

Characterization of a P-selectin-binding moiety from Bupleurum chinense polysaccharide and its antagonistic effect against P-selectin-mediated function.

P-selectin is a promising therapeutic target for acute inflammation-related diseases, and interest has been growing in the search for high-affinity glycoconjugate ligands that can target the initial P-selectin-mediated recruitment of neutrophils to the site of inflammation. In our previous study, we isolated a water-soluble polysaccharide (BCPS) from Bupleurum chinense and showed that it exhibits anti-inflammatory effect by antagonizing P-selectin-mediated adhesion of HL-60 cells to CHO-P cells. In this study, we prepared a P-selectin-based affinity chromatography medium and used it to purify the P-selectin-binding moiety of BCPS. The purified P-selectin-binding moiety of BCPS, designated as BCPS-m, was mainly composed of arabinose, galactose and glucose, and had a relative molecular weight of 3600 Da. The backbone of BCPS-m was composed of 1,5-linked arabinose, 1,4-linked and 1,4,6-linked glucose, and with branched 1-linked glucose or galactose terminal. BCPS-m could disrupt the P-selectin-mediated binding of HL-60 cells to CHO-P cells (CHO cells that stably expressed an exogenous P-selectin). It also blocked the interaction between P-selectin and its physiological ligand PSGL-1 significantly, resulting in much greater reduction (77%) in P-selectin-PSGL-1 binding than that caused by BCPS (35%). The data suggested that BCPS-m could be the key P-selectin-binding moiety of BCPS, and that it may be a better P-selectin antagonist than BCPS.