Fucose Residues Research Articles

Primary structure and anticoagulant activity of fucoidan from the sea cucumber Holothuria polii

Sea cucumber fucoidan is recently endowed with a variety of biological activities. In the present study, we studied the structure and anticoagulant effect of fucoidan from the sea cucumber Holothuria polii (Fuc-Hp). The Fuc-Hp was purified by anion exchange chromatography and its structure was characterized by FT-IR and NMR spectroscopy. Molecular weight measurements were performed by HPSEC-MALLS-dRI. Fuc-Hp anticoagulant activity was measured by activated partial thromboplastin and thrombin times, and by in vitro thrombin inhibition in the presence of antithrombin and heparin cofactor II. The assessment of thrombin generation was investigated using calibrated automated thrombography. Fuc-Hp with a high sulfate content (34.6%) and an average molecular mass of 1376.3 kDa was isolated from H. polii in amount of ~2.7 mg/g dry body wall. Primary structural analysis indicated that Fuc-Hp was mainly composed of a tetrafucose repeating unit branched by glucuronic acid. Fuc-Hp exhibited a high anticoagulant effect mediated essentially by heparin cofactor II and to lesser extent by antithrombin with IC50 values of 0.16 μg/mL and 0.5 μg/mL, respectively. Overall results showed a high anticoagulant activity of Fuc-Hp, which was attributed to the high sulfate content and abundance of disulfated fucose residues of H. polii fucoidan.

Structural characterization and anti-thrombotic properties of fucoidan from Nemacystus decipiens

The sulfated polysaccharide NP2 was isolated and purified from Nemacystus decipiens, the structure and antithrombotic activity of NP2 was further studied. NP2 was composed of fucose, glucuronic acid, galactose and xylose at molar ratios of 76.3:20.5:1.5:1.7. ES-CID-MS/MS results showed that NP2 had a backbone of α (1 → 3)-linked fucose and a branch was composed of Fuc-(2 → 1)-GlcA, which was agree with the results of NMR and methylation analysis. The results also show that the sulfate groups were substituted at the C2 or C4 positions of the fucose residues. In addition, analysis of the antithrombotic activity results indicated that NP2 can increase the percentage of t-PA/PAI-1, thereby suggesting that NP2 has high fibrinolytic activity and should be explored as a novel antithrombotic agent.

Structural characterization and RAW264.7 murine macrophage stimulating activity of a fucogalactoglucan from Colpomenia peregrina.

Water-soluble polysaccharides were isolated from Colpomenia peregrina to determine their chemical characteristics and immunomodulatory properties. High extraction yields were obtained for CP1 (17.6%) and CP2 (5.2%) polysaccharides. Polysaccharides were mainly consisted of neutral sugars (67.01-73.79%), uronic acids (9.43-14.89%), proteins (3.44-14.89%) and small amounts of sulfates (4.87-4.91%). Polysaccharides were composed of fucose (20.62-24.56%), galactose (25.5-26.94%) and glucose (50.00-52.91%) residues. The average molecular weights of the CP1 and CP2 polysaccharides were 1890 × 103g/mol and 639 × 103g/mol, respectively. The polysaccharides exerted a relatively low cytotoxicity against HeLa cancer cells (< 40%). The CP1 and CP2 polysaccharides were nontoxic and induced RAW264.7 murine macrophage cells to release considerable amounts of nitric oxide (NO). Inflammatory cytokines including IL-1β, TNF-α, IL-6, IL-10 and IL-12 from were secreted from RAW264.7 cells induced with CP1 polysaccharides. As the most immunostimulating fraction, CP1 polysaccharides were homogeneous and formed of 1,3-linked galactose, 1,4-linked glucose and 1,3-linked fucose residues. Overall, these findings suggested that the polysaccharides isolated from C. peregrina can be utilized as potential natural immunostimulant in functional foods or pharmaceutical industries.

Identity and role of the non-conserved acid/base catalytic residue in the GH29 fucosidase from the spider Nephilingis cruentata.

α-l-Fucosidases are widely occurring enzymes that remove fucose residues from N- and O-fucosylated glycoproteins. Comparison of amino acid sequences of fucosidases reveals that although the nucleophile is conserved among all α-l-fucosidases, the position of the acid/base residue is quite variable. Although several site-directed mutation studies have previously been performed on bacterial fucosidases, the only eukaryotic fucosidase so studied was the human fucosidase. Recent alignments indicate that human and Arthropoda α-l-fucosidases share at least 50% identity and the acid/base residue seems to be conserved among them suggesting a common acid/base residue in Metazoa. Here we describe the cloning and expression in Pichia pastoris of a very active α-l-fucosidase from the spider Nephilingis cruentata (NcFuc) with a Km value for pNPFuc of 0.4 mM. NcFuc hydrolyzed fucoidan, 2´fucosyllactose and also lacto-N-difucohexaose II. Mutants modified at the conserved residues D214N, E209A, E59A were expressed and characterized. The 500-fold lower kcat of D214N than the wild type was consistent with a role in catalysis, as was the 8000-fold lower kcat value of E59A. This was supported by the 57-fold increase in the kcat of E59A upon addition of azide. A complex pH/rate profile was seen for the wild-type and mutant forms of NcFuc, similar to those measured previously for the Sulfolobus fucosidase. The non-conservative catalytic structure and distinct active site organization reinforce the necessity of structural studies of new fucosidases.

A sulfated galactofucan from the brown alga Hormophysa cuneiformis (Fucales, Sargassaceae)

The brown alga Hormophysa cuneiformis collected from the coastal waters of Vietnam was used to isolate a mixture of sulfated polysaccharides FHC, which was fractionated further by anion-exchange chromatography on DEAE-Sephacel. The main fraction F3 eluted with 1.5 M NaCl contained essentially l-fucose, d-galactose and sulfate and has very complex NMR spectra. Desulfation to obtain F3deS followed by Smith degradation to obtain F3deS-Sm was used to simplify the structure of F3, and all these preparations were characterized by methylation analysis and NMR spectra. A linear (1 → 3)-linked backbone built up of α-l-fucopyranose residues was identified as the main structural motif of molecules. Some fucose residues attached to position 4 of its 3-linked neighbor were found as branches. Galactose residues having both α- and β-configurations were found mostly at the periphery of molecules. They are present as (1 → 6)-linked disaccharide of two β-d-Galp attached to position 4 of the backbone or as single α-d-Galp attached to the same position. Sulfate groups in F3 may probably occupy any positions of the molecule. F3 acts as anticoagulant and is about half as active as the standard low-molecular mass heparin (enoxaparin). FHC was practically inactive in cytotoxicity test against six human cancer cell lines.

OR32. Differential detection of glycosylation of HLA donor specific antibodies (DSA) using single antigen microbeads

Aim Differential glycosylation of Immunoglobulin G (IgG) is known to affect the functions of IgG by modulating the interactions with its binding proteins, such as C1q and Fc receptors. Our research aim was to develop an assay to analyze glycosylation of donor specific antibodies (DSA) using conventional single antigen microbead technology, and subsequently to analyze glycosylation profiles of kidney transplant patients with DSA and biopsy data for graft function assessment. Methods Conventional Class I and II LABScreen® single antigen beads were pretreated to eliminate glycans on the Class I and II antigens. Patient serum was incubated with the pretreated beads according to the standard assay. Glycans of the DSA bound to the beads were detected with biotinylated lectins known to specifically detect sialic acid, galactose, or fucose residues, along with neutravidin-PE (phycoerithrin). Data acquisition was performed using a LABScan 3D™. Results Pretreated Class I and II single antigen beads maintained DSA binding capabilities comparable to the untreated conventional beads when PAN IgG-PE was used as the detection agent. Using pretreated beads, glycans on the bound DSA were specifically detectable with lectin/neutravidin based reporters with slight modification of conventional LABScreen® single antigen protocol (Figure: Detection of Class I DSA with lectin specific to galactose vs. PAN IgG). Conclusions We have demonstrated a simple and robust assay for detection of glycans on DSA using modifications of conventional LABScreen® single antigen technology. We used lectins as specific glycan probes and neutravidin-PE as a reporter. Further research is in progress to assess the clinical validity of the assay and to assess the predictive value of glycosylation profiles of Class I and II DSA on the outcome of kidney transplant recipients. Download : Download high-res image (109KB) Download : Download full-size image

A polymeric immunoglobulin-antigen fusion protein strategy for enhancing vaccine immunogenicity.

SummaryIn this study, a strategy based on polymeric immunoglobulin G scaffolds (PIGS) was used to produce a vaccine candidate for Mycobacterium tuberculosis. A genetic fusion construct comprising genes encoding the mycobacterial Ag85B antigen, an immunoglobulin γ‐chain fragment and the tailpiece from immunoglobulin μ chain was engineered. Expression was attempted in Chinese Hamster Ovary (CHO) cells and in Nicotiana benthamiana. The recombinant protein assembled into polymeric structures (TB‐PIGS) in N. benthamiana, similar in size to polymeric IgM. These complexes were subsequently shown to bind to the complement protein C1q and FcγRs with increased affinity. Modification of the N‐glycans linked to TB‐PIGS by removal of xylose and fucose residues that are normally found in plant glycosylated proteins also resulted in increased affinity for low‐affinity FcγRs. Immunization studies in mice indicated that TB‐PIGS are highly immunogenic with and without adjuvant. However, they did not improve protective efficacy in mice against challenge with M. tuberculosis compared to conventional vaccination with BCG, suggesting that additional or alternative antigens may be needed to protect against this disease. Nevertheless, these results establish a novel platform for producing polymeric antigen‐IgG γ‐chain molecules with inherent functional characteristics that are desirable in vaccines.

Lack of complex type N-glycans lessens aberrant neuronal properties.

Modifications in surface glycans attached to proteins via N-acetylglucosamine-β1-N-asparagine linkage have been linked to tumor development and progression. These modifications include complex N-glycans with high levels of branching, fucose and sialic acid residues. Previously, we silenced Mgat2 in neuroblastoma (NB) cells, which halted the conversion of hybrid type N-glycans to complex type, to generate a novel cell line, NB_1(-Mgat2). By comparing the aberrant cell properties of the NB_1(-Mgat2) cell line to the parental cell line (NB_1), we investigated the impact of eliminating complex type N-glycans on NB cell behavior. Further, the N-glycosylation pathway in the NB_1(-Mgat2) cell line was rescued by transiently transfecting cells with Mgat2, thus creating the NB_1(-/+Mgat2) cell line. Changes in the N-glycosylation pathway were verified by enhanced binding of E-PHA and L-PHA to proteins in the rescued cell line relative to those of the NB_1(-Mgat2) cell line. Also, western blotting of total membranes from the rescued cell line ectopically expressing a voltage-gated K+ channel (Kv3.1b) revealed that N-glycans of Kv3.1b were processed to complex type. By employment of various cell lines, we demonstrated that reduction of the complex type N-glycans diminished anchorage-independent cell growth, and enhanced cell-cell interactions. Two independent cell invasion assays showed that cell invasiveness was markedly lessened by lowering the levels of complex type N-glycans while cell mobility was only slightly modified. Neurites of NB cells were shortened by the absence of complex type N-glycans. Cell proliferation was reduced in NB cells with lowered levels of complex type N-glycans which resulted from hindered progression through G1+Go phases of the cell cycle. Overall, our results illustrate that reducing the ratio of complex to hybrid types of N-glycans diminishes aberrant NB cell behavior and thereby has a suppressive effect in cell proliferation, and cell dissociation and invasion phases of NB.

Structural Studies of Fucosylated N-Glycans by Ion Mobility Mass Spectrometry and Collision-Induced Fragmentation of Negative Ions

There is considerable potential for the use of ion mobility mass spectrometry in structural glycobiology due in large part to the gas-phase separation attributes not typically observed by orthogonal methods. Here, we evaluate the capability of traveling wave ion mobility combined with negative ion collision-induced dissociation to provide structural information on N-linked glycans containing multiple fucose residues forming the Lewisx and Lewisy epitopes. These epitopes are involved in processes such as cell-cell recognition and are important as cancer biomarkers. Specific information that could be obtained from the intact N-glycans by negative ion CID included the general topology of the glycan such as the presence or absence of a bisecting GlcNAc residue and the branching pattern of the triantennary glycans. Information on the location of the fucose residues was also readily obtainable from ions specific to each antenna. Some isobaric fragment ions produced prior to ion mobility could subsequently be separated and, in some cases, provided additional valuable structural information that was missing from the CID spectra alone.Graphical abstractᅟ

Structural analysis and anticoagulant activities of two sulfated polysaccharides from the sea cucumber Holothuria coluber

Sulfated polysaccharides such as fucosylated glycosaminoglycan and fucan sulfate from echinoderm possess complex chemical structure and various biological activities. The two sulfated polysaccharides were purified from the low-value sea cucumber Holothuria coluber. Their physicochemical properties and chemical structures were analyzed and characterized by chemical and instrumental methods. Structural analysis clarified that the sea cucumber fucosylated glycosaminoglycan contains a chondroitin sulfate-like backbone and fucosyl branches with four various sulfation patterns. The fucan sulfate with molecular weight of 64.6 kDa comprises a central core of regular α(1 → 4)-linked tetrasaccharide repeating units, each of which is linked by a 4-O-sulfated fucose residue. Anticoagulant assays indicated that these sulfated polysaccharides possessed strong APTT prolonging activities and intrinsic factor Xase inhibitory activities, both of which decreased with the reduction of their molecular weights. Our results expand knowledge on the structural types of sulfated polysaccharides from sea cucumbers and further illustrate their functionality.

Lack of the α1,3-Fucosyltransferase Gene (Osfuct) Affects Anther Development and Pollen Viability in Rice.

N-linked glycosylation is one of the key post-translational modifications. α1,3-Fucosyltransferase (OsFucT) is responsible for transferring α1,3-linked fucose residues to the glycoprotein N-glycan in plants. We characterized an Osfuct mutant that displayed pleiotropic developmental defects, such as impaired anther and pollen development, diminished growth, shorter plant height, fewer tillers, and shorter panicle length and internodes under field conditions. In addition, the anthers were curved, the pollen grains were shriveled, and pollen viability and pollen number per anther decreased dramatically in the mutant. Matrix-assisted laser desorption/ionization time-of-flight analyses of the N-glycans revealed that α1,3-fucose was lacking in the N-glycan structure of the mutant. Mutant complementation revealed that the phenotype was caused by loss of Osfuct function. Transcriptome profiling also showed that several genes essential for plant developmental processes were significantly altered in the mutant, including protein kinases, transcription factors, genes involved in metabolism, genes related to protein synthesis, and hypothetical proteins. Moreover, the mutant exhibited sensitivity to an increased concentration of salt. This study facilitates a further understanding of the function of genes mediating N-glycan modification and anther and pollen development in rice.

The effect of plant lectins on the survival and malignant behaviors of thyroid cancer cells.

Altered or aberrant glycosylation is a common phenomenon in cancer cells and it originates from changes in the expression of the enzymes, glycosyltransferase, and glycosidase which up-regulate in response to some oncogenes in the glycan synthesis pathway. In this present study, it has been aimed to determine the alteration of sialic acid and fucose expressions in the cell surface of human thyroid carcinoma cells and investigate the changes in tumorigenic and malignant characters after treating them with specific plant lectins. Our study showed that the cell surface glycan chains of anaplastic 8305C, follicular FTC-133, and papillary K1 thyroid carcinoma cells were rich in α-2,6, α-2,3, sialic acid, and α-1,6 fucose residues. When the cells were treated with specific doses of Maackia amurensis lectin II (MAL), Sambucus nigra agglutinin (SNA), and Aleuria aurantia lectin (AAL) which have specific binding capacity for the detected glycan residues, respectively their cancerous traits changed dramatically. Remarkable findings obtained from MAL treatment leading to necrosis in 8505C cells without any toxicity for normal thyroid epithelial cells but it had proliferative effect on K1 and FCT-133 cells. Besides, MAL and SNA treatment decreased the mobility of 8505C and K1 cells. MAL and SNA lectins dramatically reduced the endothelial affinity of the cells and AAL significantly attenuated that of 8050C and K1 cells but not FTC-133. These results suggest that altered cell surface glycosylation in thyroid cancer seems to be a strong candidate for developing new therapeutic strategies.

First characterization of fucosidases in spiders.

l-fucose is a constituent of glycoconjugates in different organisms. Fucosidases catalyze the removal of fucose residues, and have been correlated to different physiological and pathological processes, such as fertilization, cancer, fucosidosis, and digestion in molluscs and ticks. An α-l-fucosidase sequence was identified from the transcriptome and proteome from the midgut diverticula of the synanthropic spider Nephilingis cruentata. In this article, we describe the isolation of this α-l-fucosidase and the characterization of its activity using substrates and inhibitors demonstrating different specificities among fucosidases. The enzyme had a Km of 32 and 400 μM for 4-methylumbelliferyl α-l-fucopyranoside and 4-nitrophenyl α-l-fucopyranoside, respectively; and was unable to hydrolyze fucoidan. Nephilingis cruentata α-l-fucosidase was inhibited competitively by fucose and fuconojyrimycin. The fucosidase had two distinct pH optima even in the isolated form, due to oligomerization dependent on pH, as previously described to other fucosidases. Alignment and molecular homology modeling of the protein sequence with other fucosidases indicated that the active sites and catalytic residues were different, including residues involved in acid/base catalysis. Phylogenetic analysis showed, for the first time, gene-duplication events for fucosidases in Arachnida species. All these data reveal that studies on fucosidases in organisms distinct from bacteria, fungi, and humans are important.

Molecular characterization of second tomato α1,3/4-fucosidase (α-Fuc'ase Sl-2), a member of glycosyl hydrolase family 29 active toward the core α1,3-fucosyl residue in plant N-glycans.

In a previous study, we molecular-characterized a tomato (Solanum lycopersicum) α1, 3/4-fucosidase (α-Fuc'ase Sl-1) encoded in a tomato gene (Solyc03g006980), indicating that α-Fuc'ase Sl-1 is involved in the turnover of Lea epitope-containing N-glycans. In this study, we have characterized another tomato gene (Solyc11g069010) encoding α1, 3/4-fucosidase (α-Fuc'ase Sl-2), which is also active toward the complex type N-glycans containing Lea epitope(s). The baculovirus-insect cell expression system was used to express that α-Fuc'ase Sl-2 with anti-FLAG tag, and the expression product (rFuc'ase Sl-2), was found as a 65 kDa protein using SDS-PAGE and has an optimum pH of around 5.0. Similarly to rFuc'ase Sl-1, rFuc'ase Sl-2 hydrolyzed the non-reducing terminal α1, 3-fucose residue on LNFP III and α1, 4-fucose residues of Lea epitopes on plant complex type N-glycans, but not the core α1, 3-fucose residue on Manβ1-4GlcNAcβ1-4(Fucα1-3)GlcNAc or Fucα1-3GlcNAc. However, we found that both α-Fuc'ases Sl-1 and Sl-2 were specifically active toward α1, 3-fucose residue on GlcNAcβ1-4(Fucα1-3)GlcNAc, indicating that the non-substituted β-GlcNAc linked to the proximal GlcNAc residue of the core tri-saccharide moiety of plant specific N-glycans must be a pre-requisite for α-Fuc'ase activity. A 3 D modelled structure of the catalytic sites of α-Fuc'ase Sl-2 suggested that Asp192 and Glu236 may be important for binding to the α1, 3/4 fucose residue.

Site-specific N-glycosylation analysis of soluble Fc\u03b3 receptor IIIb in human serum

Fc-receptors for immunoglobulin G (FcγRs) mediate a variety of effector and regulatory mechanisms in the immune system. N-glycosylation of FcγRs critically affects their functions which is well exemplified by antibody-dependent cell-mediated cytotoxicity (ADCC) and phagocytosis mediated by homologous FcγRIIIa and FcγRIIIb, respectively. Although several reports describe N-glycosylation profiles of recombinant FcγRIII glycoproteins, much remains unknown regarding their native glycoforms. Here we performed site-specific N-glycosylation profiling of a soluble form of FcγRIIIb purified from human serum based on mass spectrometric analysis. Our data indicate a distinct and common tendency of the glycoforms exhibited at each N-glycosylation site between the native and the previously reported recombinant FcγRIII glycoproteins. Among the six N-glycosylation sites of serum soluble FcγRIIIb, Asn45 was shown to be exclusively occupied by high-mannose-type oligosaccharides, whereas the remaining sites were solely modified by the complex-type oligosaccharides with sialic acid and fucose residues. The results of our endogenous FcγRIII glycoform analyses are important for the optimization of therapeutic antibody efficacy.

Reduced expression of α-L-Fucosidase-1 (FUCA-1) predicts recurrence and shorter cancer specific survival in luminal B LN+ breast cancer patients.

BackgroundThe lysosomal enzyme α-L-Fucosidase-1 (FUCA-1) catalyzes the hydrolytic cleavage of terminal fucose residues. FUCA-1 gene is down-regulated in highly aggressive and metastatic human tumors as its inactivation perturbs the fucosylation of proteins involved in cell adhesion, migration and metastases.ResultsNegativity to FUCA-1 was significantly related to the development of later recurrences in breast cancer patients with lymph node involvement at diagnosis. Cancer specific survival of luminal B LN+ patients was influenced by FUCA-1 expression as luminal B LN+ patients with positive expression had a longer cancer specific survival. FUCA-1 mRNA expression was inversely related to cancer stage and lymph node involvement. WB and qPCR analysis of FUCA-1 expression in breast cancer-derived cell lines confirmed an inverse relationship with tumor aggressiveness.ConclusionsThis study shows that, within LN+ breast cancer patients, FUCA-1 is able to identify a sub-set of non recurrent patients characterized by the positive expression of FUCA-1 and that, within luminal B LN+ patients, the expression of FUCA-1 predicts longer cancer specific survival.MethodsWe have analyzed FUCA-1 in 305 breast cancer patients by Immunohistochemistry (IHC), and by qPCR in breast cancer patients and in breast cancer cell lines.

Polysaccharides of Algae 71*. Polysaccharides of the Pacific brown alga Alaria marginata

The polysaccharide composition in sporophylls of the brown alga Alaria marginata enriched with laminaran and sulfated polysaccharides was studied. It was shown that laminaran molecules had an average degree of polymerization about 30 and consisted mainly of 3-linked β-D-glucopyranose residues, having no more than 10% of 1→6 linkages. The majority of chains (about 60%) were terminated at "reducing" end by mannitol residue. Alginic acid of sporophylls contained mannuronic (M) and guluronic (G) acids residues distributed along the linear polymer molecules as MM, MG, and GG blocks at a ratio of 4: 1: 1. Fucoidan was found to be composed of fucose, galactose, and sulfate as the major constituents, while xylose, mannose, glucuronic acid, and acetate were the minor components. It was shown that fucoidan contained two major components: fucan sulfate, molecules of which are built up of 3-linked fucopyranose residues with branches and sulfate groups at different positions, and fucogalactan, also containing chains of 3-linked fucopyranose residues with branches at positions 4 together with highly branched galactan chains terminated by fucose residues. The fucoidan contained also sulfated glucuronomannan and sulfated glucuronan as minor components.

Glycoprofiling of Early Gastric Cancer Using Lectin Microarray Technology.

Recently, studies have reported that protein glycosylation plays an important role in the occurrence and development of cancer. Gastric cancer is a common cancer with high morbidity and mortality owing to most gastric cancers are discovered only at an advanced stage. Here, we aim to discover novel specific serum glycanbased biomarkers for gastric cancer. A lectin microarray with 50 kinds of tumor-associated lectin was used to detect the glycan profiles of serum samples between early gastric cancer and healthy controls. Then lectin blot was performed to validate the differences. The result of the lectin microarray showed that the signal intensities of 13 lectins showed significant differences between the healthy controls and early gastric cancer. Compared to the healthy, the normalized fluorescent intensities of the lectins PWA, LEL, and STL were significantly increased, and it implied that their specifically recognized GlcNAc showed an especially elevated expression in early gastric cancer. Moreover, the binding affinity of the lectins EEL, RCA-II, RCA-I, VAL, DSA, PHA-L, UEA, and CAL were higher in the early gastric cancer than in healthy controls. These glycan structures containing GalNAc, terminal Galβ 1-4 GlcNAc, Tri/tetraantennary N-glycan, β-1, 6GlcNAc branching structure, α-linked fucose residues, and Tn antigen were elevated in gastric cancer. While the two lectins CFL GNL reduced their binding ability. In addition, their specifically recognized N-acetyl-D-galactosamine structure and (α-1,3) mannose residues were decreased in early gastric cancer. Furthermore, lectin blot results of LEL, STL, PHA-L, RCA-I were consistent with the results of the lectin microarray. The findings of our study clarify the specific alterations for glycosylation during the pathogenesis of gastric cancer. The specific high expression of GlcNAc structure may act as a potential early diagnostic marker for gastric cancer.

Structural characteristics and anticancer activity in vitro of fucoidan from brown alga Padina boryana

The sulfated and acetylated fucoidan fraction, containing fucose, galactose, mannose, glucose and uronic acid residues, was isolated from the brown alga Padina boryana. The structure of galactofucan part was studied after different modifications by NMR spectroscopy and mass spectrometry. It was shown that galactofucan contained the main chain of alternating 1,4-linked α-l-fucopyranose and 1,3-linked β-d-Galactopyranose. Single fucose residues were found as branches at C4 of galactose residues. Also, fucoidan contained 1,3- or 1,4-linked Fuc-Fuc and Gal-Gal fragments. The sulfate groups occupied positions C2, C3 and C4 of both fucose and galactose residues, which was shown by tandem mass spectrometry of fragments, labeled with heavy-oxygen. The anticancer effect of native and modified fucoidan fractions was studied in vitro on the colorectal carcinoma cells DLD-1 and HCT-116. All fucoidans had no cytotoxicity under 400 μg/mL and inhibited colony formation of cancer cells at concentration of 200 μg/mL.

Multivalent Glycomimetics with Affinity and Selectivity toward Fucose-Binding Receptors from Emerging Pathogens.

Bacterial and fungal pathogens involved in lung infection in cystic fibrosis patients utilize a particular family of glycan-binding proteins, characterized by the presentation of six fucose-binding sites on a ring-shaped scaffold. These lectins are attractive targets for anti-infectious compounds that could interfere in the recognition of host tissues by pathogens. The design of a cyclopeptide-based hexavalent structure allowed for the presentation of six fucose residues. The synthetic hexavalent compound displays liable geometry resulting in high-avidity binding by lectins from Aspergillus fumigatus and Burkholderia ambifaria. Replacing the fucose residue with a conformationally constrained fucomimetic does not alter the affinity and provides fine specificity with no binding to other fucose-specific lectins.