Important determinants for fucoidan bioactivity: a critical review of structure-function relations and extraction methods for fucose-containing sulfated polysaccharides from brown seaweeds

Systematic synthesis of sulfated oligofucosides and their effect on breast cancer MCF-7 cells

Sulfated tetrafucosides with different sulfation patterns, and a non-sulfated tetrafucoside , were designed and systematically synthesized from the common key intermediate . In addition, their anti-proliferative activities and apoptosis-inducing activities against human breast cancer MCF-7 cells were evaluated. Our results demonstrated that the sulfated tetrafucosides reduced the number of MCF-7 cells in a dose-dependent manner, and of these, 3,4-O-sulfated type showed the highest anti-proliferative activity, comparable to the activity of fucoidan isolated from Fucus vesiculosus. Furthermore, it was revealed that both and exhibited apoptosis-inducing activities through activation of caspase-8 on MCF-7 cells.

Anti-metastasis effect of fucoidan from Undaria pinnatifida sporophylls in mouse hepatocarcinoma Hca-F cells

Metastasis is one of the major causes of cancer-related death. It is a complex biological process involving multiple genes, steps, and phases. It is also closely connected to many biological activities of cancer cells, such as growth, invasion, adhesion, hematogenous metastasis, and lymphatic metastasis. Fucoidan derived from Undaria pinnatifida sporophylls (Ups-fucoidan) is a sulfated polysaccharide with more biological activities than other fucoidans. However, there is no information on the effects of Ups-fucoidan on tumor invasion and metastasis. We used the mouse hepatocarcinoma Hca-F cell line, which has high invasive and lymphatic metastasis potential in vitro and in vivo, to examine the effect of Ups-fucoidan on cancer cell invasion and metastasis. Ups-fucoidan exerted a concentration- and time-dependent inhibitory effect on tumor metastasis in vivo and inhibited Hca-F cell growth, migration, invasion, and adhesion capabilities in vitro. Ups-fucoidan inhibited growth and metastasis by downregulating vascular endothelial growth factor (VEGF) C/VEGF receptor 3, hepatocyte growth factor/c-MET, cyclin D1, cyclin-dependent kinase 4, phosphorylated (p) phosphoinositide 3-kinase, p-Akt, p-extracellular signal regulated kinase (ERK) 1/2, and nuclear transcription factor-κB (NF-κB), and suppressed adhesion and invasion by downregulating L-Selectin, and upregulating protein levels of tissue inhibitor of metalloproteinases (TIMPs). The results suggest that Ups-fucoidan suppresses Hca-F cell growth, adhesion, invasion, and metastasis capabilities and that these functions are mediated through the mechanism involving inactivation of the NF-κB pathway mediated by PI3K/Akt and ERK signaling pathways.

Anti-Proliferation Potential and Content of Fucoidan Extracted from Sporophyll of New Zealand Undaria pinnatifida

Undaria pinnatifida is a species of brown seaweed known to contain rich amounts of fucoidan, a sulfated polysaccharide known to possess various biological activities. We isolated crude fucoidan (F0) from the sporophylls of U. pinnatifida grown in the Marlborough Sounds, New Zealand. Sulfate content, uronic acid content, and molecular weight of F0 were 15.02, 1.24, and >150 kDa, respectively. F0 was fractionated to yield three further fractions: F1, F2, and F3. Cytotoxicity of two major fractions was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The algal fucoidans specifically suppressed the proliferation of three cancer cell lines with less cytotoxicity against the normal cells. Selective cytotoxicity could relate to the distinctive structures of each fucoidan fraction. Results from this study provide evidence that fucoidan, especially from U. pinnatifida grown in New Zealand, possesses great potential to be used as a functional food to reduce cancer risk or supplement cancer treatment.

Testing of potential glycan-based heparanase inhibitors in a fluorescence activity assay using either bacterial heparinase II or human heparanase

Heparanase, an endo-β-glucuronidase cleaving heparan sulfate (HS) chains at cell surfaces and in the extracellular matrix (ECM), is involved in angiogenesis, tumor progression and metastasis as well as in inflammation and kidney dysfunction. Therefore, heparanase is considered a promising therapeutic target and diagnostic marker. Recently, we have developed a simple, rapid, fully automatable fluorimetric activity assay using the synthetic sulfated pentasaccharide fondaparinux as substrate and bacterial heparinase II (HEP-II) instead of human heparanase (hHEP). The aim of this study was to evaluate this assay for inhibitor testing as well as to check whether the assay principle is applicable to measure the activity and inhibition, respectively, of the actual target enzyme hHEP. Besides the known hHEP inhibitor suramin and the antiinflammatory and antimetastatic PS3, two series of β-1,3-glucan sulfates differing in their chain length and degree of sulfation, further semisynthetic sulfated glycans, and two sulfated polysaccharides isolated from algae were included to examine structure-activity relationships. The inhibitory activity of sulfated glycans showed to be greatly dependent on both their degree of sulfation and their basic glycan structure, but independent of their molecular size. The β-1,3-glucan sulfates were superior to suramin as well as to the other glycans with similar degree of sulfations. The most active inhibitor was found to be the β-1,3-glucan sulfate PS3 (IC₅₀=0.017 μM). By using hHEP instead of HEP-II comparable results were obtained. With an IC₅₀ being about 160 times lower than that of suramin, PS3 exhibited again the strongest inhibitory effects. Inhibition of hHEP may therefore contribute to the potent antiinflammatory and antimetastatic activities of PS3 in vivo. In conclusion, the fluorimetric hHEP activity assay proved to be a simple, fully automatable tool for testing potential inhibitors. In case of HS mimetic inhibitors, the assay variant with HEP-II may provide a fast and inexpensive option for initial screening purposes.

The system of fucoidans from the brown seaweed Dictyota dichotoma: chemical analysis and antiviral activity

Room-temperature acid (pH 2) extraction of Dictyota dichotoma thalli yielded 2.2% of sulfated polysaccharides. Further extraction with the same solvent at 70°C was conducted sequentially for nine times, with a total yield of 7.2%. Fucose was the main monosaccharide only in the room-temperature extract (EAR) and in the first 70°C extract (EAH1). The remaining fractions showed increasing amounts of mannose (the main neutral monosaccharide), xylose and uronic acids. Fractionation by means of cetrimide precipitation and redissolution in increasing sodium chloride solutions has allowed obtaining several subfractions from each extract. The fractions redissolved at lower NaCl concentrations have large amounts of uronic acids and lesser sulfate contents, whereas those redissolved at higher NaCl concentrations are heavily sulfated and have low uronic acid contents. For the fucose-rich extracts (EAR and EAH1), fractionation leads to uronoxylomannofucan-rich and galactofucan-rich fractions. The remaining extracts gave rise to complex mixtures, with mannose and uronic acid-rich polysaccharides. Moderate inhibitory effect against herpes virus (HSV-1) and Coxsackie virus (CVB3) were found for the galactofucan-rich fractions. Most of the other fractions were inactive against both viruses, although some xylomannan-rich fractions were also active against HSV-1.

Healthy aging diets other than the Mediterranean: a focus on the Okinawan diet

The traditional diet in Okinawa is anchored by root vegetables (principally sweet potatoes), green and yellow vegetables, soybean-based foods, and medicinal plants. Marine foods, lean meats, fruit, medicinal garnishes and spices, tea, alcohol are also moderately consumed. Many characteristics of the traditional Okinawan diet are shared with other healthy dietary patterns, including the traditional Mediterranean diet, DASH diet, and Portfolio diet. All these dietary patterns are associated with reduced risk for cardiovascular disease, among other age-associated diseases. Overall, the important shared features of these healthy dietary patterns include: high intake of unrefined carbohydrates, moderate protein intake with emphasis on vegetables/legumes, fish, and lean meats as sources, and a healthy fat profile (higher in mono/polyunsaturated fats, lower in saturated fat; rich in omega-3). The healthy fat intake is likely one mechanism for reducing inflammation, optimizing cholesterol, and other risk factors. Additionally, the lower caloric density of plant-rich diets results in lower caloric intake with concomitant high intake of phytonutrients and antioxidants. Other shared features include low glycemic load, less inflammation and oxidative stress, and potential modulation of aging-related biological pathways. This may reduce risk for chronic age-associated diseases and promote healthy aging and longevity.

Anticancer and cancer preventive properties of marine polysaccharides: some results and prospects

Many marine-derived polysaccharides and their analogues have been reported as showing anticancer and cancer preventive properties. These compounds demonstrate interesting activities and special modes of action, differing from each other in both structure and toxicity profile. Herein, literature data concerning anticancer and cancer preventive marine polysaccharides are reviewed. The structural diversity, the biological activities, and the molecular mechanisms of their action are discussed.

Importance of sulfate groups for the macrophage-stimulating activities of ascophyllan isolated from the brown alga Ascophyllum nodosum

To investigate the role of sulfate groups on the macrophage-stimulating activities of ascophyllan, we prepared desulfated ascophyllan, and its effects on RAW264.7 cells were compared with native ascophyllan. The chemical structural analysis revealed that nearly 21% of sulfate groups of ascophyllan were removed by desulfation reaction, while no significant changes in the molecular mass and monosaccharide composition occurred after desulfation. NO- and cytokine- (TNF-α and G-CSF) inducing activities of the desulfated ascophyllan on RAW264.7 cells were significantly decreased as compared to native ascophyllan. Furthermore, the activity of desulfated ascophyllan to induce reactive oxygen species (ROS) generation from RAW264.7 cells decreased to almost negligible level. Our results suggest that the level of sulfate groups of ascophyllan is an important structural element responsible for the macrophage-stimulating activities. Probably, even the limited removal of sulfate residues sensitive to desulfation reaction may result in significant decrease in the bioactivities of ascophyllan.

Preliminary investigation of a highly sulfated galactofucan fraction isolated from the brown alga Sargassum polycystum

A fucoidan preparation was isolated from the brown alga Sargassum polycystum (Fucales, Sargassaceae). The preparation was fractionated by anion-exchange chromatography, and two highly sulfated fractions F3 and F4 were obtained. The fractions were quite similar in composition, but different in chemical structure. F4 was analyzed by chemical methods, including desulfation, methylation, Smith degradation, and partial acid hydrolysis with mass-spectrometric monitoring, as well as by NMR spectroscopy. Several 2D NMR procedures, including HMQC-TOCSY and HMQC-NOESY, were used to obtain reliable structural information from the complex spectra. Molecules of F4 were shown to contain a backbone built up mainly of 3-linked α-L-fucopyranose 4-sulfate residues, as in many other fucoidans, but rather short sequences of these residues are interspersed by single 2-linked α-D-galactopyranose residues also sulfated at position 4. This rather unusual structural feature should have a great influence on the conformation of the polymeric molecule and may be important for biological activity of the polysaccharide. Hence, F4 is an example of a new sulfated galactofucan isolated from the brown alga. According to the data obtained, the distribution of galactose residues along the polysaccharide backbone seems to be not strictly regular, but the definitive sequence of monomers in the polymeric molecules awaits additional investigation.

Influence of fucoidans on hemostatic system

Three structurally different fucoidans from the brown seaweeds Saccharina latissima (SL), Fucus vesiculosus (FV), and Cladosiphon okamuranus (CO), two chemically modified fucoidans with a higher degree of sulfation (SL-S, CO-S), and a synthetic totally sulfated octasaccharide (OS), related to fucoidans, were assessed on anticoagulant and antithrombotic activities in different in vitro experiments. The effects were shown to depend on the structural features of the compounds tested. Native fucoidan SL with a degree of sulfation (DS) of 1.3 was found to be the most active sample, fucoidan FV (DS 0.9) demonstrated moderate activity, while the polysaccharide CO (DS 0.4) was inactive in all performed experiments, even at high concentrations. Additional introduction of sulfate groups into fucoidan SL slightly decreased the anticoagulant effect of SL-S, while sulfation of CO, giving rise to the preparation CO-S, increased the activity dramatically. The high level of anticoagulant activity of polysaccharides SL, SL-S, and CO-S was explained by their ability to form ternary complexes with ATIII-Xa and ATIII-IIa, as well as to bind directly to thrombin. Synthetic per-O-sulfated octasaccharide OS showed moderate anticoagulant effect, determined mainly by the interaction of OS with the factor Xa in the presence of ATIII. Comparable tendencies were observed in the antithrombotic properties of the compounds tested.

Fucoidan from New Zealand Undaria pinnatifida: monthly variations and determination of antioxidant activities

The content and composition of fucoidans extracted from Undaria pinnatifida from mussel farms at the Marlborough Sounds, New Zealand were investigated using CaCl2 extraction. Crude fucoidan (F0) was subsequently extracted on a monthly basis from U. pinnatifida harvested from July to October 2011 from mussel farms in the Marlborough Sounds, New Zealand. Fucoidan yield varied between the frond and sporophyll parts of the algae, with the sporophyll consistently the highest content. The yield from the sporophyll increased significantly from July (25.4-26.3%) to September (57.3-69.9%). Sulphate content in the extracted fucoidan increased more than twice within the same period, while fucose content remained constant. F0 was further purified by ion-exchange chromatography to yield three fractions, F1, F2 and F3. All three fucoidan fractions contained fucose as the primary sugar component followed by galactose, with xylose, glucose and mannose as minor constituents. All fractions exhibited strong antioxidant activities using the DPPH scavenging and CUPRAC assays. This study showed that sporophyll maturation of U. pinnatifida in New Zealand influenced fucoidan content and composition. Sporophyll fucoidan could potentially be a good resource for natural antioxidants.

Application of novel extraction technologies for bioactives from marine algae

Marine algae are a rich source of bioactive compounds. This paper outlines the main bioactive compounds in marine algae and recent advances in novel technologies for extracting them. Novel extraction technologies reviewed include enzyme-assisted extraction, microwave-assisted extraction, ultrasound-assisted extraction, supercritical fluid extraction, and pressurized liquid extraction. These technologies are reviewed with respect to principles, benefits, and potential applications for marine algal bioactives. Advantages of novel technologies include higher yield, reduced treatment time, and lower cost compared to traditional solvent extraction techniques. Moreover, different combinations of novel techniques used for extraction and technologies suitable for thermolabile compounds are identified. The limitations of and challenges to employing these novel extraction technologies in industry are also highlighted.

Structural characteristics and anticancer activity of fucoidan from the brown alga Sargassum mcclurei

Three different fucoidan fractions were isolated and purified from the brown alga, Sargassum mcclurei. The SmF1 and SmF2 fucoidans are sulfated heteropolysaccharides that contain fucose, galactose, mannose, xylose and glucose. The SmF3 fucoidan is highly sulfated (35%) galactofucan, and the main chain of the polysaccharide contains a →3)-α-L-Fucp(2,4SO₃⁻)-(1→3)-α-L-Fucp(2,4SO₃⁻)-(1→ motif with 1,4-linked 3-sulfated α-L-Fucp inserts and 6-linked galactose on reducing end. Possible branching points include the 1,2,6- or 1,3,6-linked galactose and/or 1,3,4-linked fucose residues that could be glycosylated with terminal β-D-Galp residues or chains of alternating sulfated 1,3-linked α-L-Fucp and 1,4-linked β-D-Galp residues, which have been identified in galactofucans for the first time. Both α-L-Fucp and β-D-Galp residues are sulfated at C-2 and/or C-4 (and some C-6 of β-D-Galp) and potentially the C-3 of terminal β-D-Galp, 1,4-linked β-D-Galp and 1,4-linked α-L-Fucp residues. All fucoidans fractions were less cytotoxic and displayed colony formation inhibition in colon cancer DLD-1 cells. Therefore, these fucoidan fractions are potential antitumor agents.

Synergistic effect of fucoidan with antibiotics against oral pathogenic bacteria

BACKGROUND

Fucoidan is a sulphated polysaccharide that is primarily extracted from brown seaweeds; it has been broadly studied in recent years due to its numerous biological properties, including anticoagulant, antithrombotic, antitumour and antiviral activities.

OBJECTIVE AND DESIGN

In this study, fucoidan was evaluated against oral bacteria, either alone or with antibiotics, via the broth dilution method and chequerboard and time-kill assay.

RESULTS

Minimum inhibitory concentration/minimum bactericidal concentration (MIC/MBC) values for the fucoidan against all the tested bacteria ranged between 0.125 and 0.50/0.25 and 1.00mgml(-1), for ampicillin 0.125 and 64/0.5 and 64μgml(-1) and for gentamicin 2 and 256/4 and 512μgml(-1), respectively. Furthermore, the MIC and MBC were reduced to one half-eighth as a result of the combination of the fucoidan with antibiotics. One to 3h of treatment with MIC50 of fucoidan with MIC50 of antibiotics resulted from an increase of the rate of killing in colony forming units (CFUs) ml(-1) to a greater degree than was observed with alone.

CONCLUSION

These results suggest that fucoidan is important in the antibacterial actions of the agents.

Fucoidan prevents high-fat diet-induced obesity in animals by suppression of fat accumulation

This study examines the antiobesity effects of fucoidan in an animal model of diet-induced obesity. Mice were fed a standard diet or high-fat diet (HFD) for 5 weeks. After that, the mice were divided into four experimental groups, with 10 mice per group, including a standard diet group, HFD group, HFD containing 1% fucoidan (HFD + FUCO 1%) group and HFD containing 2% fucoidan (HFD + FUCO 2%) group. The fucoidan supplementation group had significantly decreased body-weight gain, food efficiency ratio and relative liver and epididymal fat mass compared with the HFD group. The mice supplemented with fucoidan showed significantly reduced triglyceride, total cholesterol and low-density lipoprotein levels in the plasma. Liver steatosis induced by the HFD improved in the fucoidan-supplemented group. Furthermore, fucoidan affected the down-regulation expression patterns of epididymal adipose tissue genes such as peroxisome proliferator-activated receptor γ, adipose-specific fatty acid binding protein and acetyl CoA carboxylase. Therefore, fucoidan may be considered for use in improving obesity.

Antiproliferative activity of fucan nanogel

Sulfated fucans comprise families of polydisperse natural polysaccharides based on sulfated L-fucose. Our aim was to investigate whether fucan nanogel induces cell-specific responses. To that end, a non toxic fucan extracted from Spatoglossum schröederi was chemically modified by grafting hexadecylamine to the polymer hydrophilic backbone. The resulting modified material (SNFuc) formed nanosized particles. The degree of substitution with hydrophobic chains was close to 100%, as estimated by elemental analysis. SNFfuc in aqueous media had a mean diameter of 123 nm and zeta potential of -38.3 ± 0.74 mV, as measured by dynamic light scattering. Nanoparticles conserved their size for up to 70 days. SNFuc cytotoxicity was determined using the MTT assay after culturing different cell lines for 24 h. Tumor-cell (HepG2, 786, H-S5) proliferation was inhibited by 2.0%-43.7% at nanogel concentrations of 0.05-0.5 mg/mL and rabbit aorta endothelial cells (RAEC) non-tumor cell line proliferation displayed inhibition of 8.0%-22.0%. On the other hand, nanogel improved Chinese hamster ovary (CHO) and monocyte macrophage cell (RAW) non-tumor cell line proliferation in the same concentration range. The antiproliferative effect against tumor cells was also confirmed using the BrdU test. Flow cytometric analysis revealed that the fucan nanogel inhibited 786 cell proliferation through caspase and caspase-independent mechanisms. In addition, SNFuc blocks 786 cell passages in the S and G2-M phases of the cell cycle.

Fucose-containing sulfated polysaccharides from brown seaweeds inhibit proliferation of melanoma cells and induce apoptosis by activation of caspase-3 in vitro

Fucose-containing sulfated polysaccharides (FCSPs) extracted from seaweeds, especially brown macro-algae, are known to possess essential bioactive properties, notably growth inhibitory effects on tumor cells. In this work, we conducted a series of in vitro studies to examine the influence of FCSPs products from Sargassumhenslowianum C. Agardh (FSAR) and Fucus vesiculosus (FVES), respectively, on proliferation of melanoma B16 cells and to investigate the underlying apoptosis promoting mechanisms. Cell viability analysis showed that both FCSPs products, i.e., FSAR and FVES, decreased the proliferation of the melanoma cells in a dose-response fashion, with FSAR being more potent at lower dosages, and FVES being relatively more anti-proliferative than FSAR at higher dosages. Flow cytometric analysis by Annexin V staining of the melanoma cells exposed to the FCSPs products confirmed that both FSAR and FVES induced apoptosis. The FCSPs-induced apoptosis was evidenced by loss of plasma membrane asymmetry and translocation of the cell membrane phospholipids and was accompanied by the activation of caspase-3. The FCSPs bioactivity is proposed to be attributable to distinct structural features of the FCSPs, particularly the presence of sulfated galactofucans (notably in S.henslowianum) and sulfated fucans (notably in F. vesiculosus). This study thus indicates that unfractionated FCSPs may exert bioactive effects on skin cancer cells via induction of apoptosis through cascades of reactions that involve activation of caspase-3.