The structure property and endothelial protective activity of fucoidan from Laminaria japonica

A comparative study of the hypolipidemic effects and mechanisms of action of Laminaria japonica- and Ascophyllum nodosum-derived fucoidans in apolipoprotein E-deficient mice

The structural characteristics of fucoidans exhibit species and regional diversity. Previous studies have demonstrated that Laminaria japonica- and Ascophyllum nodosum-derived fucoidans have type I and type II fucosyl chains, respectively. These chemical differences may contribute to distinct hypolipidemic effects and mechanisms of action. Chemical analysis demonstrated that the percentage contents of sulfate, glucuronic acid, and galactose were higher in L. japonica-derived fucoidans than those of A. nodosum-derived fucoidans. In hyperlipidemic apolipoprotein E-deficient mice, both A. nodosum- and L. japonica-derived fucoidans significantly decreased the plasma and hepatic levels of total cholesterol and triglyceride, leading to the reduction of atherosclerotic plaques. Western blotting experiments demonstrated that these fucoidans significantly enhanced the expression and levels of scavenger receptor B type 1, cholesterol 7 alpha-hydroxylase A1, and peroxisome proliferator-activated receptor (PPAR)-α, contributing to circulating lipoprotein clearance and fatty acid degradation, respectively. Differentially, L. japonica-derived fucoidan significantly increased the LXR/ATP-binding cassette G8 signaling pathway in the small intestine, as revealed by real-time quantitative PCR, which may lead to further cholesterol and other lipid excretion. Collectively, these data are useful for understanding the hypolipidemic mechanisms of action of seaweed-derived fucoidans, and their potential application for the prevention and/or treatment of atherosclerotic cardiovascular diseases.

The STING-mediated antiviral effect of fucoidan from Durvillaea antarctica

Fucoidans have attracted increasing attention due to their minimal toxicity and various biological activities, such as antioxidant, anti-inflammatory, anti-tumor and immunomodulatory effects. In this study, the antiviral effect and mechanism of fucoidan (FU) derived from Durvillaea antarctica were explored in vitro. The results demonstrated that FU effectively inhibited the infection of both RNA virus (VSV) and DNA virus (HSV-1). The potential antiviral mechanism of FU is to trigger the production of type I IFN (IFN-I) and IFN-stimulated genes dependent on the cytoplasmic DNA adaptor STING (stimulator of interferon genes), and to enhance innate immune response via activating the STING-TBK1-IRF3 pathway. FU possesses the potential to be an antiviral and immunomodulatory agent in the future.

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.

Fucoidan suppresses proliferation and epithelial-mesenchymal transition process via Wnt/β-catenin signalling in hemangioma

Hemangioma is a common benign tumour that usually occurs on the skin of the head and neck, particularly among infants. The current clinical treatment against hemangioma is surgery excision, however, application of drug is a safer and more economical therapy for children suffering from hemangioma. As a natural sulfated polysaccharide rich in brown algae, fucoidan is widely recognized for anti-tumour bioactivity and dosage safety in humans. This study aims to demonstrate the anti-tumour effect and underlying mechanism of fucoidan against hemangioma in vivo and in vitro. We investigated the effects of fucoidan by culturing hemangioma cells in vitro and treating BALB/c mice bearing with hemangioma. At first, we measured the cell proliferation and migration ability through in vitro experiments. Then, we tested the expression of epithelial-mesenchymal transition (EMT) and Wnt/β-catenin pathway-related biomarkers by western blot and qPCR. Furthermore, we applied β-catenin-specific inhibitor, XAV939, to determine whether fucoidan suppressed EMT via the Wnt/β-catenin pathway in hemangioma cells. In vivo experiments, we applied oral gavage of fucoidan to treat EOMA-bearing mice, along with evaluating the safety and efficacy of fucoidan. We found that fucoidan remarkably inhibits the proliferation and EMT ability of hemangioma cells, which is dependent on the Wnt/β-catenin pathway. These results suggest that fucoidan exhibits tumour inhibitory effect on aggressive hemangioma via regulating the Wnt/β-catenin signalling pathway both in vitro and in vivo, providing a new potent drug candidate for treating hemangioma.

Fucoidan's Molecular Targets: A Comprehensive Review of Its Unique and Multiple Targets Accounting for Promising Bioactivities Supported by In Silico Studies

Fucoidan is a class of multifunctional polysaccharides derived from marine organisms. Its unique and diversified physicochemical and chemical properties have qualified them for potential and promising pharmacological uses in human diseases, including inflammation, tumors, immunity disorders, kidney diseases, and diabetes. Physicochemical and chemical properties are the main contributors to these bioactivities. The previous literature has attributed such activities to its ability to target key enzymes and receptors involved in potential disease pathways, either directly or indirectly, where the anionic sulfate ester groups are mainly involved in these interactions. These findings also confirm the advantageous pharmacological uses of sulfated versus non-sulfated polysaccharides. The current review shall highlight the molecular targets of fucoidans, especially enzymes, and the subsequent responses via either the upregulation or downregulation of mediators' expression in various tissue abnormalities. In addition, in silico studies will be applied to support the previous findings and show the significant contributors. The current review may help in understanding the molecular mechanisms of fucoidan. Also, the findings of this review may be utilized in the design of specific oligomers inspired by fucoidan with the purpose of treating life-threatening human diseases effectively.

Natural fucoidans inhibit coronaviruses by targeting viral spike protein and host cell furin

Fucoidans are a class of long chain sulfated polysaccharides and have multiple biological functions. Herein, four natural fucoidans extracted from Fucus vesiculosus, F. serratus, Laminaria japonica and Undaria pinnatifida, were tested for their HCoV-OC43 inhibition and found to demonstrate EC50 values ranging from 0.15 to 0.61 µg/mL. That from U. pinnatifida exhibited the most potent anti-HCoV-OC43 activity with an EC50 value of 0.15 ± 0.02 µg/mL, a potency largely independent of its sulfate content. Comparison of the gene expression profiles of fucoidan-treated and untreated cells infected with HCoV-OC43 revealed that fucoidan treatment effectively diminished HCoV-OC43 gene expressions associated with induced chemokines, cytokines and viral activities. Further studies using a highly fucoidan-resistant HCoV-OC43 determined that fucoidan inhibited HCoV-OC43 infection via interfering with viral entry and led to the identification of the specific site on the N-terminal region of spike protein, that located adjacent to the host cell receptor binding domain, targeted by the virus. Furthermore, in a SARS-CoV-2 pseudovirus neutralization assay, fucoidan also blocked SARS-CoV-2 entry. In vitro and in vivo, fucoidan decreased SARS-CoV-2 viral loads and inhibited viral infection in Calu-3 or Vero E6 cells and SARS-CoV-2 infected hamsters, respectively. Fucoidan was also found to inhibit furin activity, and reported furin inhibitors were found to inhibit viral infection by wild type HCoV-OC43 or SARS-CoV-2. Accordingly, we conclude that fucoidans inhibit coronaviral infection by targeting viral spike protein and host cell furin to interfere with viral entry.

Fucoidan from Fucus vesiculosus prevents the loss of dopaminergic neurons by alleviating mitochondrial dysfunction through targeting ATP5F1a

Parkinson's disease is a neurodegenerative disease that is characterized by the loss of dopaminergic neurons. Fucoidan, which has emerged as a neuroprotective agent, is a marine-origin sulfated polysaccharide enriched in brown algae and sea cucumbers. However, variations in structural characteristics exist among fucoidans derived from different sources, resulting in a wide spectrum of biological effects. It is urgent to find the fucoidan with the strongest neuroprotective effect, and the mechanism needs to be further explored. We isolated and purified four different fucoidan species with different chemical structures and found that Type II fucoidan from Fucus vesiculosus (FvF) significantly improved mitochondrial dysfunction, prevented neuronal apoptosis, reduced dopaminergic neuron loss, and improved motor deficits in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. Further mechanistic investigation revealed that the ATP5F1a protein is a key target responsible for alleviating mitochondrial dysfunction of FvF to exert neuroprotective effects. This study highlights the favorable properties of FvF for neuroprotection, making FvF a promising candidate for the treatment of PD.

Immunopotentiating Activity of Fucoidans and Relevance to Cancer Immunotherapy

Fucoidans, discovered in 1913, are fucose-rich sulfated polysaccharides extracted mainly from brown seaweed. These versatile and nontoxic marine-origin heteropolysaccharides have a wide range of favorable biological activities, including antitumor, immunomodulatory, antiviral, antithrombotic, anticoagulant, antithrombotic, antioxidant, and lipid-lowering activities. In the early 1980s, fucoidans were first recognized for their role in supporting the immune response and later, in the 1990s, their effects on immune potentiation began to emerge. In recent years, the understanding of the immunomodulatory effects of fucoidan has expanded significantly. The ability of fucoidan(s) to activate CTL-mediated cytotoxicity against cancer cells, strong antitumor property, and robust safety profile make fucoidans desirable for effective cancer immunotherapy. This review focusses on current progress and understanding of the immunopotentiation activity of various fucoidans, emphasizing their relevance to cancer immunotherapy. Here, we will discuss the action of fucoidans in different immune cells and review how fucoidans can be used as adjuvants in conjunction with immunotherapeutic products to improve cancer treatment and clinical outcome. Some key rationales for the possible combination of fucoidans with immunotherapy will be discussed. An update is provided on human clinical studies and available registered cancer clinical trials using fucoidans while highlighting future prospects and challenges.

A Comprehensive Review of the Cardioprotective Effect of Marine Algae Polysaccharide on the Gut Microbiota

Cardiovascular disease (CVD) is the number one cause of death worldwide. Recent evidence has demonstrated an association between the gut microbiota and CVD, including heart failure, cerebrovascular illness, hypertension, and stroke. Marine algal polysaccharides (MAPs) are valuable natural sources of diverse bioactive compounds. MAPs have many pharmaceutical activities, including antioxidant, anti-inflammatory, immunomodulatory, and antidiabetic effects. Most MAPs are not utilized in the upper gastrointestinal tract; however, they are fermented by intestinal flora. The relationship between MAPs and the intestinal microbiota has drawn attention in CVD research. Hence, this review highlights the main action by which MAPs are known to affect CVD by maintaining homeostasis in the gut microbiome and producing gut microbiota-generated functional metabolites and short chain fatty acids. In addition, the effects of trimethylamine N-oxide on the gut microbiota composition, bile acid signaling properties, and CVD prevention are also discussed. This review supports the idea that focusing on the interactions between the host and gut microbiota may be promising for the prevention or treatment of CVD. MAPs are a potential sustainable source for the production of functional foods or nutraceutical products for preventing or treating CVD.

Exploring Glycan Binding Specificity of Odorranalectin by Alanine Scanning Library

Fluorescently labelled alanine scan analogues of odorranalectin (OL), a cyclic peptide that exhibits lectin like properties, were screened for binding BSA-conjugated monosaccharides using an enzyme-linked lectin assay (ELLA). Results revealed that Lys⁵, Phe⁷, Tyr⁹, Gly¹², Leu¹⁴, and Thr¹⁷ were crucial for binding BSA-L-fucose, BSA-D-galactose and BSA-N-acetyl-D-galactosamine. Notably, Ala substitution of Ser³, Pro⁴, and Val¹³ resulted in higher binding affinities compared to the native OL. The obtained data also indicated that Arg⁸ plays an important role in differentiation of binding for BSA-L-fucose/D-galactose from BSA-N-acetyl-D-galactosamine. The thermodynamics of binding of the selected alanine analogues was evaluated by isothermal titration calorimetry. Low to moderate binding affinities were determined for the tetravalent MUC1 glycopeptide and asialofetuin, respectively, and high for the fucose rich polysaccharide, fucoidan. The thermodynamic profile of interactions with asialofetuin exhibits shift to an entropy-driven mechanism compared to the fucoidan, which displayed an enthalpyentropy compensation, typically associated with the carbohydratelectin recognition process.

Protective potential of sulfated polysaccharides from tropical seaweeds against alkylating- and oxidizing-induced genotoxicity

Sulfated polysaccharides (SPs) from seaweeds are potential bioactive natural compounds, but their DNA protective activity is poorly explored. This article aimed to evaluate the genotoxic/antigenotoxic potentials of a sulfated heterofucan from brown seaweed Spatoglossum schröederi (Fucan A - FA) and a sulfated galactan from green seaweed Codium isthomocladum (3G4S) using in vitro Comet assay (alkaline and oxidative versions) with HepG2 cells. The antioxidant activity of these SPs was evaluated by total antioxidant capacity, radical scavenging, metal chelating, and antioxidant enzyme activity assays. Both SPs were not genotoxic. FA and 3G4S displayed strong antigenotoxic activity against oxidizing chemical (H₂O₂) but not against alkylating chemical (MMS). The DNA damage reduction after a pre-treatment of 72 h with these SPs was 81.42% to FA and 81.38% to 3G4S. In simultaneous exposure to FA or 3G4S with H₂O₂, HepG2 cells presented 48.04% and 55.41% of DNA damage reduction compared with the control, respectively. The antigenotoxicity of these SPs relates to direct antioxidant activity by blockage of the initiation step of the oxidative chain reaction. Therefore, we conclude that FA and 3G4S could be explored as functional natural compounds with antigenotoxic activity due to their great protection against oxidative DNA damage.

Physicochemical Properties and Anticoagulant Activity of Purified Heteropolysaccharides from Laminaria japonica

Laminaria japonica is widely consumed as a key food and medicine. Polysaccharides are one of the most plentiful constituents of this marine plant. In this study, several polysaccharide fractions with different charge numbers were obtained. Their physicochemical properties and anticoagulant activities were determined by chemical and instrumental methods. The chemical analysis showed that Laminaria japonica polysaccharides (LJPs) and the purified fractions LJP0, LJP04, LJP06, and LJP08 mainly consisted of mannose, glucuronic acid, galactose, and fucose in different mole ratios. LJP04 and LJP06 also contained minor amounts of xylose. The polysaccharide fractions eluted by higher concentration of NaCl solutions showed higher contents of uronic acid and sulfate group. Biological activity assays showed that LJPs LJP06 and LJP08 could obviously prolong the activated partial thromboplastin time (APTT), indicating that they had strong anticoagulant activity. Furthermore, we found that LJP06 exerted this activity by inhibiting intrinsic factor Xase with higher selectivity than other fractions, which may have negligible bleeding risk. The sulfate group may play an important role in the anticoagulant activity. In addition, the carboxyl group and surface morphology of these fractions may affect their anticoagulant activities. The results provide information for applications of L. japonica polysaccharides, especially LJP06 as anticoagulants in functional foods and therapeutic agents.

Polysaccharides from Laminaria japonica protect memory abilities and neurogenesis in mice after cranial irradiation through ameliorating neuroinflammation and collagen IV degradation

BACKGROUND

Radiation-induced brain injury (RIBI) is one of the most common long-term complications for patients with malignant brain tumors after radiotherapy. At present, there is no effective treatment for RIBI. Recent studies have also confirmed that polysaccharides from laminaria japonica (LJP) display potential neuroprotective function. However, its mechanisms of neuroprotection remain unclear.

AIM

In this study, we aimed to explore the effect and underlying mechanism of LJP on neurogenesis in radiation-induced brain injury mice.

METHODS

SPF two-month-old male mice were randomly divided into control group (Con), LJP treatment group (LJP), irradiation group (IR), and irradiation with LJP treatment group (IR + LJP). LJP (40 mg/kg/day) was intraperitoneally injected at one day before radiation for seven consecutive days (once daily). The mice were exposed to 10 Gy × 2 fractionated doses, once every other day, with a total dose of 20 Gy. Changes in cognitive function of mice following radiation were evaluated by the Morris water maze test. Furthermore, body weight and general status of mice were measured throughout the experiment. Immunohistochemical staining for neural proliferating cells (Ki67+ cells) and immature neurons (DCX + cells) was utilized to assay changes of neurogenesis in hippocampus. Microglial activation and collagen IV deposition within the neurogenic microenvironment were observed respectively by immunohistochemical staining for Iba-1 and Collagen IV in the hippocampus. Levels of pro-inflammatory cytokines (TNF-α and IL-1β) in the hippocampus were detected by ELISA kits post-radiation.

RESULTS

Morris water maze test showed that LJP therapy markedly reduced the escape latency and increased the times of crossing platform and percent time of the target quadrant in the radiated mice. In addition, the decrease of the neural proliferating cells (Ki67+ cells) and immature neurons (DCX + cells) in the hippocampus of mice following irradiation was significantly mitigated by the LJP treatment, suggesting that LJP could prevent from neurogenesis damage after irradiation. LJP injection significantly attenuated degradation of collagen IV, activation of microglia, and increase of pro-inflammatory cytokines (TNF-α and IL-1β) levels in the neurogenic microenvironment of the hippocampus after radiation.

CONCLUSION

These findings suggest that LJP early treatment may mitigate radiation-induced cognitive impairments and that its mechanism may relate to its protection of neurogenesis by alleviating neuroinflammation and collagen IV degradation within the neurogenic microenvironment.

Laminaria japonica fucoidan ameliorates cyclophosphamide-induced liver and kidney injury possibly by regulating Nrf2/HO-1 and TLR4/NF-κB signaling pathways

BACKGROUND

During clinical practice, cyclophosphamide (CTX) can lead to liver and kidney injury in vivo. In this study, we established a liver and kidney injury model by injecting CTX (80 mg kg-1  d-1 ) into male ICR mice, and then mice were treated with saline and fucoidan (20 or 40 mg kg-1 ), respectively. Subsequently, the liver and kidney toxicity indices, the expression levels of malonic dialdehyde (MDA), inflammatory factors, and the main protein levels of the Nrf2/HO-1 and TLR4/NF-κB pathways were determined.

RESULTS

Our results indicated that fucoidan could significantly decrease serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (CRE), and urea (BUN) in the test group compared to the model group. Fucoidan administration caused reductions in MDA, interleukin-6 (IL-6), IL-1β, and tumor necrosis factor alpha (TNF-α) levels and improved superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities in the liver and kidney of CTX-induced mice. Fucoidan up-regulated the Nrf2/HO-1 pathway and enhanced the protein levels of Nrf2, HO-1, GCLM, and NQO1. Moreover, fucoidan down-regulated the TLR4/NF-κB pathway, as indicated by decreased levels of TLR4, NF-κB p65, NF-κB p50, and increased IκBα level in liver and kidney tissues.

CONCLUSION

Our studies suggest that fucoidan can ameliorate CTX-induced liver and kidney injury, potentially via up-regulating the Nrf2/HO-1 pathway and inhibiting the TLR4/NF-κB pathway. © 2021 Society of Chemical Industry.

Isolation, structural characterization and bioactivities of polysaccharides from Laminaria japonica: A review

Laminaria japonica is a familiar marine plant and is often used as food due to its abundant carbohydrates, vitamins and minerals. As one of the main types of active substances in L. japonica, polysaccharides are widely used in the food and chemical industries and in medicine and healthcare due to their health benefits, such as immunoregulatory, antioxidant, and antidiabetic effects. However, there has been no systematic summary of the isolation, structural characterization and bioactivities of L. japonica polysaccharides (LJPs). Therefore, the present review includes a survey of extraction and purification methods for these bioactive molecules, along with a dissertation on the structural characterization of the carbohydrate components. Moreover, an overview of the most recent results related to LJP biological activities is provided. This review provides a useful reference for further research, production, and application of LJPs in functional foods and therapeutic agents.

Fucoidan for cardiovascular application and the factors mediating its activities

Fucoidan is a sulfated polysaccharide with various bioactivities. The application of fucoidan in cancer treatment, wound healing, and food industry has been extensively studied. However, the therapeutic value of fucoidan in cardiovascular diseases has been less explored. Increasing number of investigations in the past years have demonstrated the effects of fucoidan on cardiovascular system. In this review, we will focus on the bioactivities related to cardiovascular applications, for example, the modulation functions of fucoidan on coagulation system, inflammation, and vascular cells. Factors mediating those activities will be discussed in detail. Current therapeutic strategies and future opportunities and challenges will be provided to inspire and guide further research.

A comparative study of the effects of different fucoidans on cefoperazone-induced gut microbiota disturbance and intestinal inflammation

Antibiotic abuse can lead to gut microbiota disturbance and intestinal inflammation, which in turn may lead to serious inflammatory bowel disease and metabolic syndromes. To investigate the effect of fucoidan on alleviation of the side effects of antibiotics and its structure-activity relationship, we compared the effects of two fucoidan fractions with medium and low molecular weights (MF and LF) from Laminaria japonica on microbiota dysbiosis, colonic inflammation and intestinal mucosal damage in a cefoperazone-induced intestinal injury mouse model. Our results showed that oral administration of 200 mg kg-1 LF (Mw = 1.13 kDa) and MF (Mw = 26.7 kDa) together with 100 mg kg-1 cefoperazone for 10 days could significantly alleviate weight loss, colon shortening and enlargement, mucosal structural damage in the small intestine, cecum and colon induced by cefoperazone in mice. Meanwhile, LF and MF also significantly suppressed the overproduction of TNF-α, IFN-γ, and IL-6 in the colon; however, LF can restore the decrease in the levels of TNF-α and IL-6 in the small intestine and the decrease in the levels of TNF-α, IFN-γ, and IL-6 in the cecum induced by cefoperazone in mice. We found that the molecular weight of fucoidan plays an important role in the regulation of the gut microbiota in antibiotic-treated mice. Interestingly, fucoidans with different molecular weights resulted in quite different caecal microbiota communities. MF exhibited a much better effect on the restoration of the gut microbiota community richness and diversity and the beneficial bacterium Muribaculaceae. However, LF resulted in the dominance of bacteria including Staphylococcus in cefoperazone treated mice, without an increase in the community richness and diversity of caecal microbiota. In the LF and MF treated mice, an increase in the abundance of beneficial bacteria, Muribaculaceae, Acinetobacter_lwoffii and Alloprevotella, and a decrease in the abundance of harmful bacteria, e.g., Parasutterella, Helicobacter and Enterococcus were also observed. Considering the negative effect of LF on the gut microbiota, MF with a molecular weight of 26.7 kDa seemed to be a more suitable choice of prebiotics for patients receiving cefoperazone treatment.

Polysaccharides from Laminaria japonica: an insight into the current research on structural features and biological properties

Laminaria japonica, one of the most widespread seafood consumed in China and many other nations, has been traditionally utilized as an effective therapeutically active substance for treating weight loss, phlegm elimination, and detumescence for more than 2000 years. Numerous studies have found that the polysaccharides play an indispensable role in the nutritional and medicinal value of L. japonica. Water extraction and alcohol precipitation method is the most used method. Approximately 56 LJPs were successfully isolated and purified from L. japonica, whereas only few of them were well characterized. Modern pharmacological studies have shown that L. japonica polysaccharides (LJPs) have high-order structural features and multiple biological activities, including anti-tumor, anti-thrombotic, anti-atherosclerosis, hypolipidemic, hypoglycemic, antioxidant, anti-inflammatory, renoprotective, and immunomodulatory. In addition, the structural characteristics of LJPs are closely related to their biological activity. In this review, the extraction and purification methods, structural characteristics, biological activities, clinical settings, toxicities, and structure-activity relationships of LJPs are comprehensively summarized. The structural characteristics and biological activities as well as the underlying molecular mechanisms of LJPs were also outlined. Furthermore, the clinical settings and structure-activity functions of LJPs were highlighted. Some research perspectives and challenges in the study of LJPs were also proposed.

Brown seaweed Cystoseira schiffneri as a promising source of sulfated fucans: Seasonal variability of structural, chemical, and antioxidant properties

A fucoidan, sulfated polysaccharide, was extracted from the brown seaweed Cystoseira schiffneri during 4 harvest periods (December, April, July, and September) and studied for its structural and chemical properties. The Cystoseira schiffneri fucoidan (CSF) showed important variation in sulfate content ranging from 7.8% in December to 34.8% in July. This was confirmed by Fourier transform infrared and nuclear magnetic resonance spectroscopies showing characteristic signals of sulfated polysaccharides. Molecular mass of the CSF varied as a function of season from 3,745 in December to 26,390 Da in July. Gas chromatography-mass spectroscopy showed that CSF fractions were "mannogalactofucans" composed mainly of mannose, fucose, and galactose with low levels of other monosaccharides. Moreover, interesting in vitro antioxidant activities that depend on the harvest season were noted for CSF. Thus, the present work might contribute to establish criteria for extracting bioactive fucoidans from an endemic Tunisian seaweed C. schiffneri.

Fucoxanthin extracted from Laminaria Japonica inhibits metastasis and enhances the sensitivity of lung cancer to Gefitinib

ETHNOPHARMACOLOGICAL RELEVANCE

Laminaria japonica, a brown seaweed, has been used in Traditional Chinese Medicine (TCM) to treat a variety of diseases including lung cancer.

AIM OF THE STUDY

To demonstrate the effects of Fucoxanthin (FX), a major active component extracted from Laminaria japonica on metastasis and Gefitinib (Gef) sensitivity in human lung cancer cells both in vitro and in vivo.

MATERIALS AND METHODS

Invasion and migration of lung cancer cells were detected using the wound healing assay and transwell assay. Epithelial-to-mesenchymal transition (EMT) factors and PI3K/AKT/NF-κB pathways were analyzed by western blotting. RNA interference (RNAi) technology was used to silence TIMP-2 gene expression in A549 cells. The anti-metastatic effect of FX was evaluated in vivo in an experimental lung metastatic tumor model. On the other hand, cell counting kit-8 assay was used to study the cell viability of human lung cancer PC9 cells and Gef resistant PC9 cells (PC9/G) after Gef, FX or FX combined with Gef treatment. PC9 xenograft model was established to explore the anti-tumor effect of FX or combined with Gef. Immunohistochemistry staining assay and immunofluorescence staining assay were used to reveal the effects of FX on lung cancer cell proliferation and apoptosis.

RESULTS

FX was able to significantly inhibit lung cancer cells migration and invasion in vitro. FX suppressed the expressions of Snail, Twist, Fibronectin, N-cadherin, MMP-2, PI3K, p-AKT and NF-κB, and increased the expression of TIMP-2. Furthermore, knockdown of TIMP-2 attenuated FX-mediated invasion inhibition. Additionally, we demonstrated that FX inhibited lung cancer cells metastasis in vivo. The anti-metastatic effects of FX on lung cancer cells might be attributed to inhibition of EMT and PI3K/AKT/NF-κB pathway. We further demonstrated that the anti-tumor activity of FX was not only limited to the drug sensitive cell lines, but also prominent on lung cancer cells with Gef resistant phenotype. Furthermore, in vivo xenograft assay confirmed that FX inhibited tumor growth and enhanced the sensitivity of lung cancer cells to Gef and this effect may be due to inhibition of tumor cell proliferation and activation of apoptosis.

CONCLUSION

Collectively, our findings suggested that FX suppresses metastasis of lung cancer cells and overcomes EGFR TKIs resistance. Thus, FX is worthy of further investigation as a drug candidate for the treatment of lung cancer.

Galactofucan from Laminaria japonica is not degraded by the human digestive system but inhibits pancreatic lipase and modifies the intestinal microbiota

The effects of galactofucan from Laminaria japonica on the digestion and intestinal microbiota of human were investigated in the present study. Crude fraction of the sulfated polysaccharide from L. japonica (CF) and its molecular-weight homogeneous fraction (CGF-3) were prepared and characterized. In the simulated digestion model for the human saliva and gastrointestinal tract, no obvious changes in the molecular weight or the reducing sugar content of CGF-3 were observed, indicating CGF-3 is resistant to the human digestive system. Then CGF-3 did not affect the α-amylase activity while it dose-dependently inhibited the activity of pancreatic lipase partly depending on its sulfate groups. In the in vitro fermentation with the human fecal microbiota, CF did not change the total carbohydrate, reducing sugar and short chain fatty acids contents, which indicated CF was not utilized by the microbiota. However, the microbiota composition was modulated greatly by CF intervention. These findings shed a light on the better understanding of the impacts of dietary galactofucan on the digestion and intestinal microbiota.

Low molecular weight fucoidan inhibits hepatocarcinogenesis and nonalcoholic fatty liver disease in zebrafish via ASGR/STAT3/HNF4A signaling

BACKGROUND

Hepatocellular carcinoma ranks fourth in cancer-related mortality currently lacks effective therapeutics. Fucoidan is sulfated polysaccharide that is mainly found in brown seaweeds. In this study, we investigated the effects and mechanisms of low molecular weight fucoidan (i.e. oligo-fucoidan [OF]) preventing hepatocarcinogenesis.

METHODS

We used [HBx,src], [HBx,src,p53-/+ ], and [CD36] transgenic zebrafish liver cancer model treated with OF, and performed molecular and histopathological analysis. Transcriptomic and pathways analysis was performed.

RESULTS

Decreased expression of lipogenic enzymes, fibrosis markers, and cell cycle/proliferation markers by OF in [HBx,src] and [HBx,src,p53-/+ ] transgenic fish. Liver fibrosis was decreased as revealed by Sirius Red staining, and the liver cancer formation was eventually reduced by feeding OF. OF was also found to be capable of reducing lipid accumulation and cancer formation in non-B non-C Hepatocellular carcinoma (HCC) model in CD36 transgenic zebrafish. Whole-genome expression analysis showed that 661 genes were up-regulated, and 451 genes were downregulated by feeding OF. Upregulated genes were mostly found in protein transporter activity, and downregulated genes were enriched with response to extracellular stimulus and metal binding in gene ontology analysis. The driver gene was HNF4A revealed by NetworkAnalyst from OF differential regulated genes at various insults. OF is able to bind the asialoglycoprotein receptor (ASGR) in hepatoma cells, and increased the phosphorylation of signal transducer and activator of transcription 3 (STAT3) in both hepatoma cells and [HBx,src,p53-/+ ] transgenic fish liver cancer model. Using chromatin-immunoprecipitation, we found pSTAT3 could associate with the P1 promoter of HNF4A. Knockdown of either ASGR or HNF4A reversed OF mediated anti-cancer cell proliferation.

CONCLUSIONS

Taken together, we provide evidence that OF exhibits the anti-HCC, anti-steatosis, and anti-fibrosis effect for liver in zebrafish models, and the anti-cancer potential of OF attributed to the binding to ASGR and activation of STAT3/HNF4A signaling. OF might be potentially valuable for the management of HCC.

Molecular Targets and Related Biologic Activities of Fucoidan: A Review

Fucoidan-a marine natural active polysaccharide derived from brown algae with a variety of medicinal activities and low toxicity-has been used as clinical drug for renal diseases for nearly 20 years. The pharmacological mechanism of fucoidan has been well-investigated, based on target molecules and downstream signaling pathways. This review summarizes some important molecular targets of fucoidan and its related biologic activities, including scavenger receptor (SR), Toll-like receptors (TLRs), C-type lectin (CLEC) and some newly found target molecules, which may be beneficial for further understanding the pharmacological mechanism of fucoidan and discovering its new functions, as well as developing related clinical or adjuvant drugs and functional preparations.

Structural Characterization and α-Glucosidase Inhibitory and Antioxidant Activities of Fucoidans Extracted from Saccharina japonica

Two sulfated fucoidan fractions (Lj3 and Lj5) were extracted from Saccharina japonica and then subjected to acid hydrolysis to obtain Lj3h and Lj5h. Lj3h and Lj5h were characterized using IR, methylation analysis, and mass spectrometry. It was found that Lj3h and Lj5h were homogeneous low molecular weight fucoidans. Specifically, Lj3h was composed of the main chain of 1,3-linked α-L-fucopyranose residues with sulfate at C-2 and/or C-4 and three different monosaccharides (galactose, glucose, mannose) branched at C-2 and/or C-4 of fucose residue. Lj5h contained backbones of alternating galactopyranose residues and fucopyranose residues attached via a 1→3 linkage (galactofucan) and 1→6 linked galactan. The sulfation pattern was mainly located at C2/C4 fucose or galactose residues and more branches occupied at C-4 of fucose residue and C-2, C-3 or/and C-6 of galactose residue. In vitro assay indicated that, among the four fucoidans tested, only Lj5 showed potent α-glucosidase inhibitory activity with IC50 of 153.27±22.89 μg/mL, and the two parent fucoidans, Lj3 and Lj5, showed better antioxidant activity than their derivatives. These findings highlight the structure and bioactivity diversity of Saccharina japonica-derived fucoidans.

Fucoidan Isolated from Saccharina japonica Inhibits LPS-Induced Inflammation in Macrophages via Blocking NF-κB, MAPK and JAK-STAT Pathways

Fucoidan has been reported to have a variety of biological activities. However, different algae species, extraction methods, harvesting seasons, and growth regions lead to the structural variation of fucoidan, which would affect the bioactivities of fucoidan. To date, the anti-inflammatory properties and the underlying mechanism of fucoidan from brown alga Saccharina japonica (S. japonica) remain limited. The aims of the present study were to investigate the structure, the anti-inflammatory properties, and the potential molecular mechanisms of fucoidan isolated from S. japonica (SF6) against lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. SF6 was characterized using high performance liquid gel permeation chromatography (HPGPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR), and observed to be rich in fucose, galactose, and sulfate. Additionally, results showed that SF6 remarkably inhibited LPS-induced production of various inflammatory mediators and pro-inflammation cytokines, including nitric oxide (NO), NO synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-β (IL-β), and interleukin-6 (IL-6). A mechanism study showed that SF6 could effectively inhibit inflammatory responses through blocking LPS-induced inflammation pathways, including nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and Janus kinase (JAK)-2 and signal transducer and activator of transcription (STAT)-1/3 pathways. These results suggested that SF6 has the potential to be developed as an anti-inflammatory agent applied in functional food.

Low Molecular Weight Fucoidan Prevents Radiation-Induced Fibrosis and Secondary Tumors in a Zebrafish Model

Radiotherapy often causes unwanted side effects such as radiation-induced fibrosis and second malignancies. Fucoidan, a sulfated polysaccharide extracted from brown seaweed, has many biological effects including anti-inflammation and anti-tumor. In the present study, we investigated the radioprotective effect of Oligo-Fucoidan (OF) using a zebrafish animal model. Adult zebrafish of wild-type and transgenic fish with hepatocellular carcinoma were orally fed with Oligo-Fucoidan before irradiation. Quantitative PCR, Sirius red stain, hematoxylin, and eosin stain were used for molecular and pathological analysis. Whole genomic microarrays were used to discover the global program of gene expression after Oligo-Fucoidan treatment and identified distinct classes of up- and downregulated genes/pathways during this process. Using Oligo-Fucoidan oral gavage in adult wild-type zebrafish, we found Oligo-Fucoidan pretreatment decreased irradiation-induced fibrosis in hepatocyte. Using hepatitis B virus X antigen (HBx), Src and HBx, Src, p53−/+ transgenic zebrafish liver cancer model, we found that Oligo-Fucoidan pretreatment before irradiation could lower the expression of lipogenic factors and enzymes, fibrosis, and cell cycle/proliferation markers, which eventually reduced formation of liver cancer compared to irradiation alone. Gene ontology analysis revealed that Oligo-Fucoidan pretreatment increased the expression of genes involved in oxidoreductase activity in zebrafish irradiation. Oligo-Fucoidan also decreased the expression of genes involved in transferase activity in wild-type fish without irradiation (WT), nuclear outer membrane-endoplasmic reticulum membrane network, and non-homologous end-joining (NHEJ) in hepatocellular carcinoma (HCC) transgenic fish. Rescue of those genes can prevent liver cancer formation. Conclusions: Our results provide evidence for the ability of Oligo-Fucoidan to prevent radiation-induced fibrosis and second malignancies in zebrafish.

Brown Seaweed Fucoidan in Cancer: Implications in Metastasis and Drug Resistance

Fucoidans are sulphated polysaccharides that can be obtained from brown seaweed and marine invertebrates. They have anti-cancer properties, through their targeting of several signaling pathways and molecular mechanisms within malignant cells. This review describes the chemical structure diversity of fucoidans and their similarity with other molecules such as glycosaminoglycan, which enable them to participation in diverse biological processes. Furthermore, this review summarizes their influence on the development of metastasis and drug resistance, which are the main obstacles to cure cancer. Finally, this article discusses how fucoidans have been used in clinical trials to evaluate their potential synergy with other anti-cancer therapies.

In vitro anticancer activity of fucoidan extracted from Sargassum cinereum against Caco-2 cells

Fucoidan is a marine sulfated polysaccharide, which is extracted from brown seaweed that has a wide range of bioactivities including anti-cancer properties. However, the underlying mechanism of fucoidan on its anti-cancer and apoptotic activity against colon cancer cell line Caco-2 remains to be elucidated. Hence, the present study evaluated the cytotoxicity, apoptotic and anti-cancer activity of fucoidan extracted from brown seaweed Sargassum cinereum against Caco-2 cell line. Cytotoxicity, morphological examination of nuclei, mitochondrial membrane potential, flow cytometry, reactive oxygen species (ROS) formation and detection of apoptotic efficacy of fucoidan were assessed by different assay protocols. Fucoidan inhibited growth of Caco-2 cells in a dose-dependent manner. IC50 concentration of fucoidan was found to be 250 μg/ml. AO/EB, Hoechst and Annexin V/PI staining confirmed the apoptosis induced by fucoidan in Caco-2 cells. Fucoidan was also found to increase ROS production and augment mitochondrial membrane permeability. The findings of the study suggest that fucoidan exerts potent anti-cancer and apoptotic effect on Caco-2 cells by enhancing ROS production. Thus, fucoidan may be used as a promising therapeutic regimen against various cancer cell types.

Recent Advances in Pharmaceutical Potential of Brown Algal Polysaccharides and their Derivatives

Marine plants, animals and microorganisms display steady growth in the ocean and are abundant carbohydrate resources. Specifically, natural polysaccharides obtained from brown algae have been drawing increasing attention owing to their great potential in pharmaceutical applications. This review describes the structural and biological features of brown algal polysaccharides, including alginates, fucoidans, and laminarins, and it highlights recently developed approaches used to obtain the oligo- and polysaccharides with defined structures. Functional modification of these polysaccharides promotes their advanced applications in biomedical materials for controlled release and targeted drug delivery, etc. Moreover, brown algal polysaccharides and their derivatives possess numerous biological activities with anticancer, anticoagulant, wound healing, and antiviral properties. In addition, we also discuss carbohydrate- based substrates from brown algae, which are currently in clinical and preclinical studies, as well as the marine drugs that are already on the market. The present review summarizes the recent development in carbohydratebased products from brown algae, with promising findings that could rapidly facilitate the future discovery of novel marine drugs.

Production Inhibition and Excretion Promotion of Urate by Fucoidan from Laminaria japonica in Adenine-Induced Hyperuricemic Mice

This work aims to explore the amelioration of fucoidan on adenine-induced hyperuricemia and hepatorental damage. Adenine-induced hyperuricemic mice were administered with fucoidan, allopurinol and vehicle control respectively to compare the effects of the drugs. Serum uric acid, urea nitrogen, hepatorenal functions, activities of hepatic adenosine deaminase (ADA), xanthine oxidase (XOD), renal urate transporter 1 (URAT1) and NF-κB p65 were assessed. As the serum uric acid, urea nitrogen, creatinine, glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) data demonstrated, the adenine not only mediated hepatorenal function disorders, but also induced hyperuricemia in mice. Meanwhile, activities of hepatic ADA and XOD were markedly augmented by adenine, and the expression of URAT1 was promoted, which was conducive to the reabsorption of urate. However, exposure to fucoidan completely reversed those adenine-induced negative alternations in mice, and the activities of hepatic ADA and XOD were recovered to the normal level. It was obvious that hepatic and renal functions were protected by fucoidan treatment. The expression of URAT1 was returned to normal, resulting in an increase of renal urate excretion and consequent healing of adenine-induced hyperuricemia in mice. Expression and activation of NF-κB p65 was promoted in kidneys of adenine treated mice, but suppressed in kidneys of mice exposed to fucoidan from Laminaria japonica or allopurinol. In conclusion, the fucoidan is a potential therapeutic agent for the treatment of hyperuricemia through dual regulatory roles on inhibition of hepatic metabolism and promotion of renal excretion of urate.

Synthesis of Fucoidan-Mimetic Glycopolymers with Well-Defined Sulfation Patterns via Emulsion Ring-Opening Metathesis Polymerization

The approach developed here offers distinct and well-defined glycopolymers for deciphering the biological roles of natural bioactive polysaccharides. Fucose monomers were chemically synthesized and decorated with specific sulfation patterns including unsulfate, monosulfate, disulfate, and trisulfate groups. The six fucoidan-mimetic glycopolymers (18-23) were successfully fabricated through microwave-assisted ring-opening metathesis polymerization (ROMP) in an emulsion system. The molecular weight (M_w), polydispersity index (PDI), and multiple functional groups were fully characterized by SEC-MALLS-RI and NMR spectroscopy. Three glycopolymers (19, 21, 23) associated with 2-O-sulfation exhibited better inhibitory effects on the H1N1 virus, while glycopolymers (19, 20) with monosulfate groups were more effective against the H3N2 virus. These findings would promote the development of novel anti-influenza A virus (IAV) drugs based on natural fucoidans.

Low molecular weight fucoidan attenuates experimental abdominal aortic aneurysm through interfering the leukocyte-endothelial cells interaction

Low molecular weight fucoidan (LMWF) is a sulfated polysaccharide extracted from Saccharina Japonica that presents high affinity for P-selectin and abolish selectin-dependent recruitment of leukocytes. We hypothesized that dietary intake of LMWF, as a competitive binding agent of P-selectin, could limit the inflammatory infiltration and aneurysmal growth in an Angiotensin II-induced abdominal aortic aneurysm (AAA) mouse model. The Gene Expression Omnibus database was used for gene expressions and gene set enrichment analysis. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that focal adhesion was involved in the development of AAA. However, dietary intake of LMWF could limit the enlargement of AAA, decreasing maximal aortic diameter and preserving elastin lamellae. Although LMWF did not decrease the circulatory monocytes count and lower the expression of P-selectin in endothelium, it reduced macrophages infiltration in media and adventitia. Furthermore, matrix metalloproteinase expression was markedly downregulated, accompanied with reduced expression of inflammatory mediators, including interleukin 1β, tumor necrosis factor-α and monocyte chemotactic protein-1. The present study revealed a novel target for the treatment of AAA and the anti-inflammatory effects of LMWF.