Fucoidan Derivatives Research Articles

Synthesis of Low-Molecular-Weight Fucoidan Analogue and Its Inhibitory Activities against Heparanase and SARS-CoV-2 Infection.

Heparan sulfate (HS) is ubiquitous on cell surfaces and is used as a receptor by many viruses including SARS-CoV-2. However, increased activity of the inflammatory enzyme heparanase (HPSE), which hydrolyses HS, in patients with COVID-19 not only increases the severity of symptoms but also may facilitate the spread of the virus by degrading HS on the cell surface. Therefore, synthetic HPSE blockades, which can bind to SARS-CoV-2 spike protein (SARS-CoV-2-S) and inhibit viral entry, have attracted much attention. This study investigated the development of a new dual-targeting antiviral agent against HPSE and SARS-CoV-2-S using fucoidan as a structural motif. It was found that all-sulfated fucoidan derivative 10, which exhibited the highest binding affinity to SARS-CoV-2-S among 13 derivatives, also showed the highest inhibitory activity against HPSE. Based on this, a newly designed and synthesized fucoidan analogue 16, in which the octyl group of 10 was changed to a cholestanyl group, was found to show higher activity than 10 but did not inhibit factor Xa associated with undesired anticoagulant effects. The binding affinity of 16 to SARS-CoV-2-S was significantly increased approximately 400-fold over that of 10.Furthermore, 16 effectively inhibited infection by the SARS-CoV-2 Wuhan strain and two Omicron subvariants.

Synthesis of Low‐Molecular‐Weight Fucoidan Analogue and Its Inhibitory Activities against Heparanase and SARS‐CoV‐2 Infection

Heparan sulfate (HS) is ubiquitous on cell surfaces and is used as a receptor by many viruses including SARS‐CoV‐2. However, increased activity of the inflammatory enzyme heparanase (HPSE), which hydrolyses HS, in patients with COVID‐19 not only increases the severity of symptoms but also may facilitate the spread of the virus by degrading HS on the cell surface. Therefore, synthetic HPSE blockades, which can bind to SARS‐CoV‐2 spike protein (SARS‐CoV‐2‐S) and inhibit viral entry, have attracted much attention. This study investigated the development of a new dual‐targeting antiviral agent against HPSE and SARS‐CoV‐2‐S using fucoidan as a structural motif. It was found that all‐sulfated fucoidan derivative 10, which exhibited the highest binding affinity to SARS‐CoV‐2‐S among 13 derivatives, also showed the highest inhibitory activity against HPSE. Based on this, a newly designed and synthesized fucoidan analogue 16, in which the octyl group of 10 was changed to a cholestanyl group, was found to show higher activity than 10 but did not inhibit factor Xa associated with undesired anticoagulant effects. The binding affinity of 16 to SARS‐CoV‐2‐S was significantly increased approximately 400‐fold over that of 10. Furthermore, 16 effectively inhibited infection by the SARS‐CoV‐2 Wuhan strain and two Omicron subvariants.

The Discovery of the Fucoidan-Active Endo-1→4-α-L-Fucanase of the GH168 Family, Which Produces Fucoidan Derivatives with Regular Sulfation and Anticoagulant Activity.

Sulfated polysaccharides of brown algae, fucoidans, are known for their anticoagulant properties, similar to animal heparin. Their complex and irregular structure is the main bottleneck in standardization and in defining the relationship between their structure and bioactivity. Fucoidan-active enzymes can be effective tools to overcome these problems. In the present work, we identified the gene fwf5 encoding the fucoidan-active endo-fucanase of the GH168 family in the marine bacterium Wenyingzhuangia fucanilytica CZ1127T. The biochemical characteristics of the recombinant fucanase FWf5 were investigated. Fucanase FWf5 was shown to catalyze the endo-type cleavage of the 1→4-O-glycosidic linkages between 2-O-sulfated α-L-fucose residues in fucoidans composed of the alternating 1→3- and 1→4-linked residues of sulfated α-L-fucose. This is the first report on the endo-1→4-α-L-fucanases (EC 3.2.1.212) of the GH168 family. The endo-fucanase FWf5 was used to selectively produce high- and low-molecular-weight fucoidan derivatives containing either regular alternating 2-O- and 2,4-di-O-sulfation or regular 2-O-sulfation. The polymeric 2,4-di-O-sulfated fucoidan derivative was shown to have significantly greater in vitro anticoagulant properties than 2-O-sulfated derivatives. The results have demonstrated a new type specificity among fucanases of the GH168 family and the prospects of using such enzymes to obtain standard fucoidan preparations with regular sulfation and high anticoagulant properties.

Production of high- and low-molecular weight fucoidan fragments with defined sulfation patterns and heightened in vitro anticancer activity against TNBC cells using novel endo-fucanases of the GH107 family

Fucoidans are complex fucose-containing sulfated polysaccharides with pronounced anticancer effects. Their structure-anticancer activity relationships are difficult to determine due to fucoidans' complex, often irregularities-including structures. Fucoidan-active enzymes can be used for this propose. We have investigated two new recombinant endo-fucanases FWf3 and FWf4 from the marine bacterium Wenyingzhuangia fucanilytica CZ1127T that belong to the 107 family of glycoside hydrolases (GH). Both enzymes cleaved α-(1→4)-glycosidic bonds but in fucoidan fragments with different sulfation patterns. FWf3 is the first characterized endo-fucanase that cleaves glycosidic bonds between 2O- and 2,4diO-sulfated L-fucose residues. The obtained endo-fucanases were used to produce low- and high-molecular weight fucoidan derivatives with different sulfate group locations. Low- and high-molecular weight fucoidan derivatives rich with 2,4diO-sulfation were shown to inhibit MDA-MB-231 cell colony formation more efficiently than the native fucoidan and the derivatives sulfated otherwise. Such derivatives effectively suppressed the mitochondrial membrane potential of MDA-MB-231 cells and reduced the expression of the glucose transporter 1 (GLUT1). Co-treatment of MDA-MB-231 cells with the fucoidan derivatives and oligomycin (an OXPHOS inhibitor) resulted in a synergistic anticancer effect. The data obtained demonstrate, that fucoidan and its 2,4diO-sulfated derivatives can be an effective adjunct in TNBC therapy targeting cell metabolism.

Combined Radiomodifying Effect of Fucoidan from the Brown Alga Saccharina cichorioides and Pacificusoside D from the Starfish Solaster pacificus in the Model of 3D Melanoma Cells.

Cancer is one of the main causes of human mortality worldwide. Despite the advances in the diagnostics, surgery, radiotherapy, and chemotherapy, the search for more effective treatment regimens and drug combinations are relevant. This work aimed to assess the radiomodifying effect and molecular mechanism of action of fucoidan from the brown alga Saccharina cichorioides (ScF) and product of its autohydrolysis (ScF_AH) in combination with pacificusoside D from the starfish Solaster pacificus (SpD) on the model of viability and invasion of three-dimension (3D) human melanoma cells SK-MEL-2. The cytotoxicity of ScF (IC50 JB6 Cl41 > 800 µg/mL; IC50 SK-MEL-2 = 685.7 µg/mL), ScF_AH (IC50 JB6 Cl41/SK-MEL-2 > 800 µg/mL), SpD (IC50 JB6 Cl41 = 22 µM; IC50 SK-MEL-2 = 5.5 µM), and X-ray (ID50 JB6 Cl41 = 11.7 Gy; ID50 SK-MEL-2 = 6.7 Gy) was determined using MTS assay. The efficiency of two-component treatment of 3D SK-MEL-2 cells was revealed for ScF in combination with SpD or X-ray but not for the combination of fucoidan derivative ScF_AH with SpD or X-ray. The pre-treatment of spheroids with ScF, followed by cell irradiation with X-ray and treatment with SpD (three-component treatment) at low non-toxic concentrations, led to significant inhibition of the spheroids' viability and invasion and appeared to be the most effective therapeutic scheme for SK-MEL-2 cells. The molecular mechanism of radiomodifying effect of ScF with SpD was associated with the activation of the initiator and effector caspases, which in turn caused the DNA degradation in SK-MEL-2 cells as determined by the Western blotting and DNA comet assays. Thus, the combination of fucoidan from brown algae and triterpene glycoside from starfish with radiotherapy might contribute to the development of highly effective method for melanoma therapy.

Discovery of a fucoidan endo-4O-sulfatase: Regioselective 4O-desulfation of fucoidans and its effect on anticancer activity in vitro

Fucoidans are a class of sulfated fucose-containing bioactive polysaccharides produced by brown algae. The biological effects exhibited by fucoidans are thought to be related to their sulfation. However, the lack of methods for sulfation control does not allow for a reliable conclusion about the influence of the position of certain sulfate groups on the observed biological effects. We identified the gene encoding the endo-acting fucoidan sulfatase swf5 in the marine bacterium Wenyingzhuangia fucanilytica CZ1127T. This is the first report on the sequence of fucoidan endo-sulfatase. Sulfatase SWF5 belongs to the subfamily S1_22 of the family S1. SWF5 was shown to remove 4O-sulfation in fucoidans composed from the alternating α-(1→3)- and α-(1→4)-linked residues of sulfated L-fucose but not from fucoidans with the α-(1→3)-linked backbone. The endo-sulfatase was used to selectively prepare 4O-desulfated fucoidan derivatives. It was shown that the 4O-desulfated fucoidans inhibit colony formation of DLD-1 and MCF-7 cells less effectively than unmodified fucoidans. Presumably, 4O-sulfation makes a significant contribution to the anticancer activity of fucoidans.

Discovering mycobacterial lectins as potential drug targets and vaccine candidates for tuberculosis treatment: a theoretical approach.

M. tuberculosis proliferates within the macrophages during infection and they are bounded by carbohydrates in the cell wall, called lectins. Despite their surface localization, the studies on exact functions of lectins are unexplored. Hence, in our study, using insilico approaches, 11 potential lectins of Mtb was explored as potential drug targets and vaccine candidates. Initially, a gene interaction network was constructed for the 11 potential lectins and identified its functional partners. A gene ontology analysis was also performed for the 11 mycobacterial lectins along with its functional partners and found most of the proteins are present in the extracellular region of the bacterium and belongs to the PE/PPE family of proteins. Further, molecular docking studies were performed for two of the potential lectins (Rv2075c and Rv1917c). A novel series of quinoxalinone and fucoidan derivatives have been made to dock against these selected lectins. Molecular docking study reveals that quinoxalinone derivatives showed better affinity against Rv2075c, whereas fucoidan derivatives have good binding affinity against Rv1917c. Moreover, the mycobacterial lectins can interact with the host and they are considered as potential vaccine candidates. Hence, immunoinformatics study was carried out for all the 11 potential lectins. B-cell and T-cell binding epitopes were predicted using insilico tools. Further, an immunodominant epitope 1062SIPAIPLSVEV1072 of Rv1917c was identified, which was predicted to bind B-cell and most of the MHC alleles. Thus, the study has explored that mycobacterial lectins could be potentially used as drug targets and vaccine candidates for tuberculosis treatment.Supplementary InformationThe online version contains supplementary material available at 10.1007/s42485-021-00065-y.

Synthesis of low-molecular weight fucoidan derivatives and their binding abilities to SARS-CoV-2 spike proteins.

Fucoidan derivatives 10-13, whose basic sugar chains are composed of repeating α(1,4)-linked l-fucopyranosyl residues with different sulfation patterns, were designed and systematically synthesized. A structure-activity relationship (SAR) study examined competitive inhibition by thirteen fucoidan derivatives against heparin binding to the SARS-CoV-2 spike (S) protein. The results showed for the first time that 10 exhibited the highest inhibitory activity of the fucoidan derivatives used. The inhibitory activity of 10 was much higher than that of fondaparinux, the reported ligand of SARS-CoV-2 S protein. Furthermore, 10 exhibited inhibitory activities against the binding of heparin with several mutant SARS-CoV-2 S proteins, but was found to not inhibit factor Xa (FXa) activity that could otherwise lead to undesirable anticoagulant activity.

Potential Beneficial Actions of Fucoidan in Brain and Liver Injury, Disease, and Intoxication-Potential Implication of Sirtuins.

Increased interest in natural antioxidants has brought to light the fucoidans (sulfated polysaccharides present in brown marine algae) as highly valued nutrients as well as effective and safe therapeutics against several diseases. Based on their satisfactory in vitro antioxidant potency, researchers have identified this molecule as an efficient remedy for neuropathological as well as metabolic disorders. Some of this therapeutic activity is accomplished by upregulation of cytoprotective molecular pathways capable of restoring the enzymatic antioxidant activity and normal mitochondrial functions. Sirtuin-3 has been discovered as a key player for achieving the neuroprotective role of fucoidan by managing these pathways, whose ultimate goal is retrieving the entirety of the antioxidant response and preventing apoptosis of neurons, thereby averting neurodegeneration and brain injuries. Another pathway whereby fucoidan exerts neuroprotective capabilities is by interactions with P-selectin on endothelial cells, thereby preventing macrophages from entering the brain proper. Furthermore, beneficial influences of fucoidan have been established in hepatocytes after xenobiotic induced liver injury by decreasing transaminase leakage and autophagy as well as obtaining optimal levels of intracellular fiber, which ultimately prevents fibrosis. The hepatoprotective role of this marine polysaccharide also includes a sirtuin, namely sirtuin-1 overexpression, which alleviates obesity and insulin resistance through suppression of hyperglycemia, reducing inflammation and stimulation of enzymatic antioxidant response. While fucoidan is very effective in animal models for brain injury and neuronal degeneration, in general, it is accepted that fucoidan shows somewhat limited potency in liver. Thus far, it has been used in large doses for treatment of acute liver injuries. Thus, it appears that further optimization of fucoidan derivatives may establish enhanced versatility for treatments of various disorders, in addition to brain injury and disease.

Gradual degradation of fucoidan from Fucus vesiculosus and its effect on structure, antioxidant and antiproliferative activities

The fucose-containing sulfated polysaccharides (syn. fucoidans) from brown algae exhibit a wide range of bioactivities and are therefore considered promising candidates for health-supporting and medical applications. During the past three decades, research on isolation, molecular characterization, and screening of in vitro and in vivo pharmacological activities has significantly increased. Until now, however, fucoidans are only used as ingredients in cosmetics and food supplements, especially due to the proclaimed antioxidant activities of fucoidan. One obstacle to medical applications is the usually high molecular mass of native fucoidans, as it is associated with unfavorable biopharmaceutical properties and possibly undesired effects. Therefore, it seems reasonable to develop fucoidan derivatives with reduced size. So far, in this study, fucoidan from Fucus vesiculosus was gradually degraded from Mw 38.2 down to 4.9 kDa without concomitant desulfation. Compared to hydrothermal treatment, the degradation with H2O2 showed to be more efficient and additionally eliminated the antioxidant and antiproliferative activities of the genuine fucoidan. This confirmed our previous hypothesis that rather co-extracted compounds like terpenoids and polyphenols than the fucoidan itself exhibit these effects.

The effect of different substitute groups and molecular weights of fucoidan on neuroprotective and anticomplement activity

Ten fucoidan (FPS) derivatives were successfully synthesized, and their potential neuroprotective and anticomplement activities were investigated employing various established in vitro systems. The aim of the present study was to investigate the effects of different substitute groups and molecular weights of fucoidan on neuroprotective and anticomplement activities. All FPS derivatives possessed considerable neuroprotective and anticomplement activities and had stronger activities than FPS in certain tests. The in vitro results found that sulfated and benzoylated derivatives could reverse the decreased mitochondrial activity and decreased lactate dehydrogenase (LDH) and reactive oxygen species (ROS) release induced by 6-hydroxydopamine (6-OHDA, P<0.01 or P<0.001), which provides further evidence that sulfate and benzoylate groups could enhance the neuroprotective activity of fucoidan. In anticomplement experiments, all samples showed anticomplement activity in both systems; however, the sulfated and benzoylated derivatives showed better activity than fucoidan, with higher molecular weights showing the strongest activity. Available data suggested that substituted groups of fucoidan played an important role on neuroprotective and anticomplement activities. The mechanism of the influence of the neuroprotective and anticomplement activities of samples of the substituted groups was indicated.

Gene identification and characterization of fucoidan deacetylase for potential application to fucoidan degradation and diversification

Fucoidan is an α-l-fucopyranosyl polymer found in seaweeds with forms that have acetyl and sulfuric modifications and derivatives that are lower and/or diversified, with modifications that have attracted interest as potential bioactive substances. We identified the gene for a fucoidan deacetylase that cleaves acetyl moieties from fucoidan and thereby contributes to fucoidan utilization in the marine bacterium Luteolibacter algae H18. Fucoidan deacetylase was purified to homogeneity from a cell-free extract of L.algae H18, and used to determine the internal amino acid sequence and identify the gene, fud, in a draft genome sequence of the H18 strain. The gene product was heterologously produced in Escherichia coli and was demonstrated to catalyze fucoidan deacetylation, but not desulfation, and degradation into lower forms. In addition to fucoidan deacetylation, the enzyme catalyzed the hydrolysis of p-nitrophenyl esters with organic acids, and p-nitrophenyl acetate was the best substrate among those tested. The present study provides a new tool for fucoidan degradation, potentially expanding investigations on fucoidan derivatives.

Structural features and anticancer activity in vitro of fucoidan derivatives from brown alga Saccharina cichorioides

A fucoidan ScF from brown alga Saccharina cichorioides was extracted, purified and partially depolymerized by autohydrolysis at 37°C for 24, 48 and 72h. Supernatant (SN) and pellet (PL) fractions were obtained by ethanol precipitation of each sample. Unlike spectral data of ScF, NMR of PL derivatives clearly suggested the structure: 1,3-linked α-l-Fucp-4-OSO3− repeating unit. Molecular weights (MWs) of PL fractions were 30, 26 and 18kDa for 24, 48 and 72h of autohydrolyis, respectively. MALDI-TOFMS, size-exclusion HPLC and carbohydrate polyacrylamide-gel electrophoresis (C-PAGE) indicated a similarity of SN mixtures. They consisted mainly of a polysaccharide part (MW 6kDa, C-PAGE data) with a structure similar to PL components (NMR data) and monosaccharides α-l-Fucp-4-OSO3−, α-l-Fucp-2,4-di-OSO3−. PL fractions exhibited almost identical antiproliferative activity in vitro as native fucoidan, while an SN sample for 72h of autohydrolysis was slightly more active against colony formation of colorectal carcinoma cells HT-29.

Structure, chemical and enzymatic modification, and anticancer activity of polysaccharides from the brown alga Turbinaria ornata

In this study, water-soluble polysaccharides from the brown alga Turbinaria ornata (laminaran ToL, fucoidans ToF1 and ToF2) were obtained. The anticancer activity of these polysaccharides and modified derivatives of fucoidan ToF2 against several cancer cell lines was studied. The structure of fucoidan ToF2 was thoroughly investigated using methylation analysis of polysaccharides and mass spectrometry of low molecular weight derivatives of fucoidan, released by fucoidanase from the marine mollusk Patinopecten yessoensis. Fucoidan ToF2 contained a main chain, built up of (1 → 3)-linked fucose residues with branches of single residues or short chains, consisting of fucose and galactose at C2 and C4, and single HexA residues at C2. The following fragments were identified in the structure of fucoidan: Fuc-2,4-SO3 −-(1 → 2)-Fuc, Fuc-2-SO3 −-(1 → 4)-Fuc-2-SO3 −, Gal-2-SO3 −-(1 → 3)-2-SO3 −-Fuc, Fuc-4-SO3 −-(1 → 4)- Gal-3-SO3 −, Fuc-2-SO3 −-(1 → 4)-Gal-3-SO3 −-(1 → 4)-Fuc, Gal-4-SO3 −-(1 → 4)-, Fuc-4-SO3 −-(1 → 3)-Fuc, and HexA-(1 → 2)-Fuc-4-SO3 −. Sulfate groups occupied the positions at C2 and/or at C4 of fucose and C2, C3, and C4/C6 of galactose residues. The fucoidan ToF2 and its derivative obtained by enzymatic hydrolysis inhibited colony formation of human colorectal, breast adenocarcinoma, and malignant melanoma cell lines in vitro.

Systematic synthesis of low-molecular weight fucoidan derivatives and their effect on cancer cells

Low-molecular weight type I and II fucoidan derivatives with different sulfation patterns were designed and systematically synthesized from the corresponding common key intermediate and their anti-proliferative activities and apoptosis-inducing activities against human breast cancer (MCF-7) and human cervical epithelioid carcinoma (HeLa) cells were evaluated. Our results demonstrated that one of the type II fucoidan derivatives, 9, effectively reduced the number of viable MCF-7 and HeLa cells in a dose-dependent manner without causing cytotoxicity toward normal WI-38 cells, and that the anti-proliferative activity of 9 was comparable to that of fucoidan 2 isolated from Fucus vesiculosus. Moreover, it was found that both 2 and 9 exhibited similar apoptosis-inducing activities through activation of caspase-8 and -9 on MCF-7 and HeLa cells, respectively.

Effect and mechanism of fucoidan derivatives from Laminaria japonica in experimental adenine-induced chronic kidney disease

Ethnopharmacological relevanceLaminaria japonica is a popular seafood and medicinal plant in China, Chinese people use them as a traditional medicine for curing edema disease, a symptom of kidney diseases. Materials and methodsThe renal protective activity and mechanism of fucoidan derivatives was studied against adenine induced CKD in rats. The fucoidan derivatives were administered at dose of 50 and 150mg/kg body weight. The serum urea nitrogen (SUN), serum creatinine (SCR) and some enzymic activity were detected. ResultsThe SUN and SCR level decreased significantly with fucoidan derivatives administration. Histopathological changes of renal tubules and interstitium were markedly alleviated by fucoidan derivatives and the mesangial areas were also greatly reduced. Alterations were observed in the activities/levels of serum enzymic (CAT, GSH-PX) and non-enzymic (GSH) antioxidants, along with high level of malondialdehyde (MDA) in the CKD rats. However, normalized lipid peroxidation and antioxidant defenses occurred with fucoidan derivatives administration. ConclusionThis study exhibited a new mechanism of fucoidan derivatives on CKD rats, that was the samples could alleviate renal tubules, interstitium and mesangial areas mediated by replacing the electronegative content of the glomerular cells and inhibition of mesangial cell proliferation. The study also proved the mechanism of fucoidan derivatives on the CKD rats had relationship with their antioxidant activities, the samples which could enhance the activity of antioxidant enzymes and reduce the LPO level could alleviate the symptom of CKD.

In-vitro anticoagulant activity of fucoidan derivatives from brown seaweed Laminaria japonica

Fucoidan, a group of sulfated heteropolysaccharides, was extracted from Laminaria japonica, an important economic alga species in China. The anticoagulant activity of fucoidan and its derivatives (including sulfated, phosphorylated, and aminated fucoidan) was examined using in-vitro anticoagulant systems. The correlation between chemical variations within the fucoidan group and anticoagulant activity was determined. The in-vitro anticoagulant properties of fucoidan and its derivatives were determined by measuring activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). The results indicate anticoagulant activity in all samples using APTT and TT assays; however, only the fucoidan derivatives affected the PT assay. Thus, the fucoidan derivatives were able to inhibit both intrinsic and extrinsic blood coagulants. Fucoidan (FPS) and its derivatives presented better anticoagulant activity than low molecular weight fucoidan (DFPS) and its derivatives, suggesting that molecular weight and proper conformation are contributing factors for anticoagulant activity of polysaccharides. Amino groups have a positive charge and can thus change the charge density of fucoidan. Accordingly, among the tested samples, aminated fucoidan (NF) was the most active reflecting the importance of charge density for anticoagulant activity. Available data obtained using in-vitro models suggest that the sulfate content, sulfate/total-sugar ratio, molecular weight, and the substituted group of fucoidan are important factors for anticoagulant activity but that the influence of sulfate, phosphate and amino groups on anticoagulant activity was different.

Immunostimulatory Activity of Fucoidan from the Brown Alga Fucus evanescens: Role of Sulfates and Acetates

Fucoidans are natural polysaccharides mainly consisting of sulfated α-L-fucopyranose. A wide range of biological activities has been attributed to fucoidans. However, their immunostimulatory role with respect to structure-activity relationships is still under debate. To address this question, hyposulfated (hypoS), deacetylated (deAc), and both hyposulfated and deacetylated (hypoSdeAc) derivatives of native Fucus evanescens fucoidan were used to stimulate bone marrow–derived dendritic cells (BMDCs) and bone marrow–derived macrophages (BMMs). Native fucoidan induced proinflammatory cytokines (IL-1β, IL-6, IL-12, TNF-α) by murine BMDCs and BMMs. Hyposulfation led to a markedly reduced cytokine secretion by BMDCs (35% to 70% reduction compared to native fucoidan) and BMMs (60% to 90% reduction). Cytokine release was also largely decreased by deacetylation (50% to 60% reduction in BMDCs, 50% to 70% reduction in BMMs compared to native fucoidan). In BMDCs and BMMs stimulated with hypoSdeAc, cytokine production was almost completely abolished. In conclusion, our results indicate the importance of sulfate/acetyl groups for the immunostimulatory activity of fucoidans.

Relationship between oversulfation and conformation of low and high molecular weight fucoidans and evaluation of their in vitro anticancer activity.

Low and high molecular weight fucoidans (F5-30K and F>30K) were chemically modified through the addition of sulfate groups, and the effect of oversulfation on the in vitro anticancer activity was investigated. After the addition of sulfate groups, a considerable increase of 35.5 to 56.8% was observed in the sulfate content of the F5-30K fraction, while the sulfate content of the F>30K fraction increased to a lesser extent (from 31.7 to 41.2%). Significant differences in anticancer activity were observed between the oversulfated F5–30K and F>30K fractions, with activities of 37.3–68.0% and 20.6–35.8%, respectively. This variation in the anticancer activity of oversulfated fucoidan derivatives was likely due to differences in their sulfate content. The results suggest that the molecular conformation of these molecules is closely related to the extent of sulfation in the fucan backbones and that the sulfates are preferably substituted when the fucoidan polymers are in a loose molecular conformation.

Synthesized different derivatives of low molecular fucoidan extracted from Laminaria japonica and their potential antioxidant activity in vitro

Six low molecular fucoidan (DFPS) derivatives were synthesized successfully, and their potential antioxidant activities were investigated employing various established in vitro systems. All DFPS derivatives possessed considerable antioxidant activity, and had stronger antioxidant ability than DFPS in certain tests. The benzoylated DFPS (PHDF) showed strongest scavenging activity on superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, however, DFPS exhibited greatest reducing power. Available data suggested that substituted groups of DFPS played an important role on antioxidant activity, and the mechanism on influence the antioxidant activity of samples of substituted group was indicated.