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Paulo A.s. Mourão - One of the best experts on this subject based on the ideXlab platform.
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Is the antithrombotic effect of sulfated Galactans independent of serpin
Journal of thrombosis and haemostasis : JTH, 2014Co-Authors: Ana Luíza Gomes Quinderé, Gustavo R.c. Santos, Stephan-nicollas M. C. G. Oliveira, Bianca F. Glauser, Bruno Pedrosa Fontes, Ismael Nilo Lino De Queiroz, Norma Maria Barros Benevides, Vitor H. Pomin, Paulo A.s. MourãoAbstract:Summary Background Sulfated Galactans are polysaccharides with heterogeneous structures that frequently show anticoagulant activity. Their anticoagulant mechanisms are complex and distinct from those observed for heparin. Sulfated Galactans act through a combination of effects involving serpin-dependent and serpin-independent mechanisms. Interestingly, these polymers can also induce blood coagulation due to activation of factor XII (FXII). Objectives The structure of a complex sulfated galactan from the red alga Acanthophora muscoides was characterized by solution nuclear magnetic resonance. This polysaccharide and another previously characterized algal sulfated galactan from Botryocladia occidentalis were each used in in vitro and in vivo anticoagulant and antithrombotic assays to understand the possible structural determinants of their functional effects. Results and Conclusions The serpin-dependent anticoagulant effects and FXII-related procoagulant effects of the sulfated Galactans decreased in parallel with the molecular size. The serpin-independent anticoagulation also correlated with the chemical structure of the sulfated Galactans. The sulfated galactan from A. muscoides, which showed mostly serpin-independent anticoagulant activity and reduced activation of FXII, drastically reduced arterial thrombus formation. However, the sulfated Galactans produced opposite effects on venous thrombosis; this difference appears to result from the tenuous balance between the various effects on coagulation, including serpin-dependent and serpin-independent anticoagulation and FXIIa-dependent procoagulation. This study of novel sulfated polysaccharides with distinct effects on coagulation and thrombosis helps to establish the minimal structural-function relationship required for the development of antithrombotic drugs.
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a unique 2 sulfated β galactan from the egg jelly of the sea urchin glyptocidaris crenularis conformation flexibility versus induction of the sperm acrosome reaction
Journal of Biological Chemistry, 2009Co-Authors: M Castro, Vitor H. Pomin, Livia Loiola Dos Santos, Anacristina E S Vilelasilva, Noritaka Hirohashi, Laercio Polfachin, Hugo Verli, Paulo A.s. MourãoAbstract:Sulfated polysaccharides from the egg jelly of sea urchins act as species-specific inducers of the sperm acrosome reaction, which is a rare molecular mechanism of carbohydrate-induced signal-transduction event in animal cells. The sea urchin polysaccharides differ in monosaccharide composition (l-fucose or l-galactose), glycosylation, and sulfation sites, but they are always in the α-anomeric configuration. Herein, structural analysis of the polysaccharide from the sea urchin Glyptocidaris crenularis surprisingly revealed a unique sulfated β-d-galactan composed by (3-β-d-Galp-2(OSO3)-1→3-β-d-Galp-1)n repeating units. Subsequently, we used the G. crenularis galactan to compare different 2-sulfated polysaccharides as inducers of the acrosome reaction using homologous and heterologous sperm. We also tested the effect of chemically over-sulfated Galactans. Intriguingly, the anomeric configuration of the glycosidic linkage rather than the monosaccharide composition (galactose or fucose) is the preferential structural requirement for the effect of these polysaccharides on sea urchin fertilization. Nuclear magnetic resonance and molecular dynamics indicate that sulfated α-galactan or α-fucan have less dynamic structural behavior, exhibiting fewer conformational populations, with an almost exclusive conformational state with glycosidic dihedral angles Φ/Ψ = −102°/131°. The preponderant conformer observed in the sulfated α-galactan or α-fucan is not observed among populations in the β-form despite its more flexible structure in solution. Possibly, a proper spatial arrangement is required for interaction of the sea urchin-sulfated polysaccharides with the specific sperm receptor.
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Structure, biology, evolution, and medical importance of sulfated fucans and Galactans.
Glycobiology, 2008Co-Authors: Vitor H. Pomin, Paulo A.s. MourãoAbstract:Sulfated fucans and Galactans are strongly anionic polysaccharides found in marine organisms. Their structures vary among species, but their major features are conserved among phyla. Sulfated fucans are found in marine brown algae and echinoderms, whereas sulfated Galactans occur in red and green algae, marine angiosperms, tunicates (ascidians), and sea urchins. Polysaccharides with 3-linked, β-galactose units are highly conserved in some taxonomic groups of marine organisms and show a strong tendency toward 4-sulfation in algae and marine angiosperms, and 2-sulfation in invertebrates. Marine algae mainly express sulfated polysaccharides with complex, heterogeneous structures, whereas marine invertebrates synthesize sulfated fucans and sulfated Galactans with regular repetitive structures. These polysaccharides are structural components of the extracellular matrix. Sulfated fucans and Galactans are involved in sea urchin fertilization acting as species-specific inducers of the sperm acrosome reaction. Because of this function the structural evolution of sulfated fucans could be a component in the speciation process. The algal and invertebrate polysaccharides are also potent anticoagulant agents of mammalian blood and represent a potential source of compounds for antithrombotic therapies.
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slight differences in sulfation of algal Galactans account for differences in their anticoagulant and venous antithrombotic activities
Thrombosis and Haemostasis, 2008Co-Authors: Roberto J C Fonseca, Fabio R Melo, Stephan-nicollas M. C. G. Oliveira, Norma Maria Barros Benevides, Maria G Pereira, Paulo A.s. MourãoAbstract:We compared sulfated Galactans (SGs) from two species of red algae using specific coagulation assays and experimental models of thrombosis.These polysaccharides have an identical saccharide structure and the same size chain, but with slight differences in their sulfation patterns.As a consequence of these differences, the two SGs differ in their anticoagulant and venous antithrombotic activities.SG from G.crinale exhibits procoagulant and prothrombotic effects in low doses (up to 1.0 mg/kg body weight), but in high doses (>1.0 mg/kg) this polysaccharide inhibits both venous and arterial thrombosis in rats and prolongs ex-vivo recalcification time. In contrast, SG from B. occidentalis is a very potent anticoagulant and antithrombotic compound in low doses (up to 0.5 mg/kg body weight), inhibiting venous experimental thrombosis and prolonging ex-vivo recalcification time, but these effects are reverted in high doses. Only at high doses (>1.0 mg/kg) the SG from B. occidentalis inhibits arterial thrombosis. As with heparin, SG from G. crinale does not activate factor XII, while the polysaccharide from B. occidentalis activates factor XII in high concentrations, which could account for its procoagulant effect at high doses on rats. Both SGs do not modify bleeding time in rats.These results indicate that slight differences in the proportions and/or distribution of sulfated residues along the galactan chain may be critical for the interaction between proteases, inhibitors and activators of the coagulation system, resulting in a distinct pattern in anti- and procoagulant activities and in the antithrombotic action.
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a preponderantly 4 sulfated 3 linked galactan from the green alga codium isthmocladum
Glycobiology, 2007Co-Authors: Eduardo H C Farias, Ana Paula Valente, Vitor H. Pomin, Helena B Nader, Hugo Alexandre Oliveira Rocha, Paulo A.s. MourãoAbstract:The green algae of the genus Codium have recently been demonstrated to be an important source of sulfated Galactans from the marine environment. Here, a sulfated galactan was isolated from the species Codium isthmocladum and its structure was studied by a combination of chemical analyses and NMR spectroscopy. Two fractions (SG 1, approximately 14 kDa, and SG 2, approximately 20 kDa) were derived from this highly polydisperse and heterogeneous polysaccharide. Both exhibited similar structures in (1)H 1D NMR spectra. The structural features of SG 2 and its desulfated derivative were analyzed by COSY, TOCSY, DEPT-HSQC, HSQC, and HMBC. This sulfated galactan is composed preponderantly of 4-sulfated, 3-linked beta-D-galactopyranosyl units. In minor amounts, it is sulfated and glycosylated at C-6. Pyruvate groups are also found, forming five-membered cyclic ketals as 3,4-O-(1'carboxy)-ethylidene-beta-D-galactose residues. A comparison of sulfated Galactans from different marine taxonomic groups revealed similar backbones of 3-beta-D-Galp-1.
Marina Ciancia - One of the best experts on this subject based on the ideXlab platform.
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Structural Diversity in Galactans From Red Seaweeds and Its Influence on Rheological Properties.
Frontiers in plant science, 2020Co-Authors: Marina Ciancia, María C. Matulewicz, Rando TuvikeneAbstract:Galactans are important components of many plant cell walls. Besides, they are the major polysaccharides in extracellular matrixes from different seaweeds, and other marine organisms, which have an acidic character due to the presence of sulfate groups in their structures. In particular, most of the red seaweeds biosynthesize sulfated Galactans with very special linear backbones, constituted by alternating (1→3)-β-d-galactopyranose units (A-unit) and (1→4)-α-galactopyranose residues (B-unit). In the industrially significant seaweeds as source of hydrocolloids, B-units belong either to the d-series and they produce carrageenans (as in the order Gigartinales), or to the l-series, and they are sources of agarose and/or structurally related polymers (i.e., Gelidiales, Gracilariales). In both cases, the latter units appear as cyclized 3,6-anhydro-α-galactose in certain amounts, which can be increased by alkaline cyclization of α-galactose 6-sulfate units. Besides, it has been clearly shown that some red algae produce different amounts of both galactan structures, known as d/l-hybrids. It is not yet clear if they comprise both diasteromeric types of units in the same molecule, or if they are mixtures of carrageenans and agarans that are very difficult to separate. It has been reported that the biosynthesis of these Galactans, showing that the nucleotide transport for d-galactopyranose units is UDP-d-Gal, while for l-galactose, it is GDP-l-Gal, so, there is a different pathway in the biosynthesis of agarans. However, at least in those seaweeds that produce carrageenans as major Galactans, but also agarans, both synthetic pathways should coexist. Another interesting characteristic of these Galactans is the important variation in the sulfation patterns, which modulate their physical behavior in aqueous solutions. Although the most common carrageenans are of the κ/ι- and λ-types (with A-units sulfated at the 4- and 2-positions, respectively) and usually in agarans, when sulfated, is at the 6-position, many other sulfate arrangements have been reported, greatly influencing the functional properties of the corresponding Galactans. Other substituents can modify their structures, as methyl ethers, pyruvic acid ketals, acetates, and single stubs of xylose or other monosaccharides. It has been shown that structural heterogeneity at some extent is essential for the proper functional performance of red algal Galactans.
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Determination of Substitution Patterns of Galactans from Green Seaweeds of the Bryopsidales.
Methods in molecular biology (Clifton N.J.), 2015Co-Authors: Paula Ximena Arata, Paula Virginia Fernández, Marina CianciaAbstract:Sulfated and pyruvylated Galactans are the major soluble polysaccharides produced by seaweeds of the Bryopsidales. Their backbones have a complex and variable pattern of substitution which, until now, has only been elucidated for a few species. Methods for determination of sulfate and pyruvic acid content, and chemical strategies to determine their position in the galactan chain are outlined here. These methods can also be applied to other sulfated and/or pyruvylated polysaccharides.
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Characterization of cell wall polysaccharides of the coencocytic green seaweed bryopsis plumosa (bryopsidaceae, chlorophyta) from the argentine coast
Journal of Phycology, 2012Co-Authors: Marina Ciancia, Josefina S. Alberghina, Paula Ximena Arata, Hugo Benavides, Heroen Verbruggen, Jose Manuel EstevezAbstract:Bryopsis sp. from a restricted area of the rocky shore of Mar del Plata (Argentina) on the Atlantic coast was identified as Bryopsis plumosa (Hudson) C. Agardh (Bryopsidales, Chlorophyta) based on morphological characters and rbcL and tufA DNA barcodes. To analyze the cell wall polysaccharides of this seaweed, the major room temperature (B1) and 90°C (X1) water extracts were studied. By linkage analysis and NMR spectroscopy, the structure of a sulfated galactan was determined, and putative sulfated rhamnan structures and furanosidic nonsulfated arabinan structures were also found. By anion exchange chromatography of X1, a fraction (F4), comprising a sulfated galactan as major structure was isolated. Structural analysis showed a linear backbone constituted of 3-linked β-d-galactose units, partially sulfated on C-6 and partially substituted with pyruvic acid forming an acetal linked to O-4 and O-6. This galactan has common structural features with those of green seaweeds of the genus Codium (Bryopsidales, Chlorophyta), but some important differences were also found. This is the first report about the structure of the water-soluble polysaccharides biosynthesized by seaweeds of the genus Bryopsis. These sulfated Galactans and rhamnans were in situ localized mostly in two layers, one close to the plasma membrane and the other close to the apoplast, leaving a middle amorphous, unstained cell wall zone. In addition, fibrillar polysaccharides, comprising (1→3)-β-d-xylans and cellulose, were obtained by treatment of the residue from the water extractions with an LiCl/DMSO solution at high temperature. These polymers were also localized in a bilayer arrangement.
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the system of sulfated Galactans from the red seaweed gymnogongrus torulosus phyllophoraceae rhodophyta location and structural analysis
Carbohydrate Polymers, 2008Co-Authors: José M. Estevez, Marina Ciancia, Alberto S. CerezoAbstract:Abstract Sulfated polysaccharides were localized in the cuticle, cortex and medulla of the gametophyte thallus, being more concentrated in the intercellular matrix than in the cell walls. During the water extraction sequence, a small percentage of galactan sulfates (5.1% of dry seaweed) with average low M r (6–11.4 kDa) were extracted at room temperature without disturbing the cellular arrangement, while sulfated Galactans of average medium M r (18–45 kDa) were obtained by further hot-water extractions (52.4% of dry seaweed), with diorganization of the tissue. The residue (40.0% of dry seaweed) still contained carrageenan-type (major) and agaran-type (minor) Galactans. Part of these Galactans was extracted with 8.4% LiCl solution in DMSO, from which “pure” κ/ι-carrageenans were isolated. Carrageenans and agarans were extracted in a ratio 1:0.5, showing the highest amount of agaran-structures for a carrageenophyte. The Galactans comprise alternating 4-sulfated (major) and non-sulfated (minor) 3-linked β- d -galactopyranose units, and 4-linked α-galactopyranose units with the following substitutions: (i) non-sulfated and 2-sulfated 3,6-anhydro-α- d -galactopyranose residues in the carrageenan-structures, which belong to the κ-family (κ/ι-carrageenans); (ii) 3-sulfated α- l -galactopyranose units and 2-sulfated 3,6-anhydro-α- l -galactopyranose residues in the agaran-structures. Alkaline treatment and alkaline dialysis of the main extracts gave “pure” κ/ι-carrageenans, showing that carrageenan molecules are extracted together with low M r agarans or agaran- dl -hybrids.
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The system of Galactans of the red seaweed, Kappaphycus alvarezii, with emphasis on its minor constituents
Carbohydrate research, 2004Co-Authors: José M. Estevez, Marina Ciancia, Alberto S. CerezoAbstract:The Galactans extracted with hot water from Kappaphycus alvarezii, after previous extraction at room temperature, are mainly composed of j-carrageenans (� 74%) and l-carrageenans (� 3%). However, a significant percentage of these Galactans (at least 14%) is composed of sulfated agarans and, possibly, agaran-type sulfated DL-hybrid Galactans. These agarans are partially sub- stituted on C-2 or C-4 or disubstituted on both positions of the b-D-galactose units and on C-3 or C-2 and C-3 of the a-L-galactose residues with sulfate groups or single stubs of b-D
Mirko Bunzel - One of the best experts on this subject based on the ideXlab platform.
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Detailed Structural Characterization of Arabinans and Galactans of 14 Apple Cultivars Before and After Cold Storage.
Frontiers in Plant Science, 2018Co-Authors: Daniel Wefers, Ramona Flörchinger, Mirko BunzelAbstract:Physiological and textural properties of apples are greatly influenced by both cultivar and structural composition of their pectic polysaccharides. In previous studies it was demonstrated that neutral pectic side chains (arabinans and Galactans) play a major role during fruit development and postharvest processes. However, these complex polymers have a high structural heterogeneity, and some structural elements such as side chain substituents and substitution of neighboring residues cannot be analyzed by using conventional analytical methods. Therefore, fine structures of arabinans and Galactans were analyzed in 14 apple cultivars before and after storage. Besides conventional methods such as methylation analysis, profiling approaches based on enzymatic cleavage were applied to obtain detailed information on the neutral side chains of pectins. Structurally different, highly branched arabinans and linear β-1,4-linked Galactans were detected in all cultivars. By using enzymatic profiling approaches, rare structural elements such as β-arabinofuranose and α-arabinopyranose residues were detected. In addition, the combination of all methods indicated structural differences with regard to ramification position or patterns. Cold storage resulted in decreased portions of branched arabinans. It was demonstrated that arabinan decomposition is independent of previously detected structural variations. In addition, analysis of endo-arabinanase hydrolysates demonstrated that β-arabinofuranose containing side chains are enriched after storage and may play a major role in postharvest processes. Analysis of endo galactanase hydrolysates showed decreased portions of galactan-bound, terminal α-arabinopyranose units after storage. Therefore, these residues are most likely removed during postharvest galactan decomposition. The results of this study demonstrate the high complexity of neutral pectin side chains in apples and that pectic structural elements are differently prone to postharvest modifications.
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Data_Sheet_1_Detailed Structural Characterization of Arabinans and Galactans of 14 Apple Cultivars Before and After Cold Storage.pdf
2018Co-Authors: Daniel Wefers, Ramona Flörchinger, Mirko BunzelAbstract:Physiological and textural properties of apples are greatly influenced by both cultivar and structural composition of their pectic polysaccharides. In previous studies, it was demonstrated that neutral pectic side chains (arabinans and Galactans) play a major role during fruit development and postharvest processes. However, these complex polymers have a high structural heterogeneity, and some structural elements such as side chain substituents and substitution of neighboring residues cannot be analyzed by using conventional analytical methods. Therefore, fine structures of arabinans and Galactans were analyzed in 14 apple cultivars before and after storage. Besides conventional methods such as methylation analysis, profiling approaches based on enzymatic cleavage were applied to obtain detailed information on the neutral side chains of pectins. Structurally different, highly branched arabinans and linear β-1,4-linked Galactans were detected in all cultivars. By using enzymatic profiling approaches, rare structural elements such as β-arabinofuranose and α-arabinopyranose residues were detected. In addition, the combination of all methods indicated structural differences with regard to ramification position or patterns. Cold storage resulted in decreased portions of branched arabinans. It was demonstrated that arabinan decomposition is independent of previously detected structural variations. In addition, analysis of endo-arabinanase hydrolysates demonstrated that β-arabinofuranose containing side chains are enriched after storage and may play a major role in postharvest processes. Analysis of endo-galactanase hydrolysates showed decreased portions of galactan-bound, terminal α-arabinopyranose units after storage. Therefore, these residues are most likely removed during postharvest galactan decomposition. The results of this study demonstrate the high complexity of neutral pectin side chains in apples and that pectic structural elements are differently prone to postharvest modifications.
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NMR Spectroscopic Profiling of Arabinan and Galactan Structural Elements
Journal of agricultural and food chemistry, 2016Co-Authors: Daniel Wefers, Mirko BunzelAbstract:Pectic arabinans and Galactans presumably affect the physiological and technological properties of plant cell walls and dietary fiber. Their complex structures are usually analyzed by time-consuming methods, which are based on chemical cleavage to monomers. To gain more detailed insights into the arabinan and galactan structures, a time-efficient approach based on enzymatic cleavage and two-dimensional NMR spectroscopy was developed. Heteronuclear single quantum coherence spectroscopy (HSQC) marker signals were evaluated for various structural elements, and relative response factors were determined, allowing a semiquantitative estimation of the structural composition. The method was applied to analyze different insoluble plant materials and soluble polysaccharides. It was demonstrated that the developed approach yielded comparable information about various structural elements that can also be detected by using the conventional methylation analysis. However, by using the NMR method, additional structural i...
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Arabinan and Galactan Oligosaccharide Profiling by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD)
2016Co-Authors: Daniel Wefers, Mirko BunzelAbstract:Arabinans and Galactans are complex pectic polysaccharides, which greatly influence the physicochemical and physiological properties of plants and plant-based foods. Conventional methods to characterize these challenging polymers are based on derivatization and/or unselective chemical cleavage of the glycosidic bonds of the polysaccharides, resulting in partial loss of essential information such as anomeric configuration. Here, endo-arabinanase and endo-galactanase were used to selectively cleave pectic arabinans and Galactans. The liberated oligosaccharides were purified and characterized by LC-MS and one- and two-dimensional NMR spectroscopy resulting in known but also several previously unknown pectic structural elements. For the routine analysis of pectin hydrolysates by HPAEC-PAD, incubation conditions, chromatographic parameters, and relative response factors of the isolated pectic oligosaccharides against an internal standard were determined. The applicability of the method was demonstrated by analyzing different well-characterized plant cell wall materials. It was demonstrated that the developed method yields additional information about pectic arabinan and galactan structures that is not obtained from conventional methods such as methylation analysis
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NMR Spectroscopic Profiling of Arabinan and Galactan Structural Elements
2016Co-Authors: Daniel Wefers, Mirko BunzelAbstract:Pectic arabinans and Galactans presumably affect the physiological and technological properties of plant cell walls and dietary fiber. Their complex structures are usually analyzed by time-consuming methods, which are based on chemical cleavage to monomers. To gain more detailed insights into the arabinan and galactan structures, a time-efficient approach based on enzymatic cleavage and two-dimensional NMR spectroscopy was developed. Heteronuclear single quantum coherence spectroscopy (HSQC) marker signals were evaluated for various structural elements, and relative response factors were determined, allowing a semiquantitative estimation of the structural composition. The method was applied to analyze different insoluble plant materials and soluble polysaccharides. It was demonstrated that the developed approach yielded comparable information about various structural elements that can also be detected by using the conventional methylation analysis. However, by using the NMR method, additional structural information, such as the anomeric configuration of the monomers, is obtained, demonstrating the value of this novel approach
Alberto S. Cerezo - One of the best experts on this subject based on the ideXlab platform.
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Galactans from cryptonemia species part ii studies on the system of Galactans of cryptonemia seminervis halymeniales and on the structure of major fractions
Carbohydrate Research, 2009Co-Authors: Rosiane G.m. Zibetti, Miguel D. Noseda, Maria Eugênia R. Duarte, Franciely G Colodi, Diogo R B Ducatti, Luciana G Ferreira, Marco Andre Cardoso, Alberto S. CerezoAbstract:Abstract Cryptonemia seminervis biosynthesizes a family of d , l -hybrid Galactans based on the classical 3-linked β- d -galactopyranosyl→4-linked α- d - and α- l -galactopyranosyl alternating sequence (A-units→B-units) with major amounts of α- d - and α- l -galactose and 3,6-anhydro- d - and l -galactose and lesser percentages of 3,6-anhydro-2-O-methyl- l -galactose, 2-O-methyl-, 4-O-methyl- and 6-O-methylgalactoses. The dispersion of structures in this family is based on five structural factors, namely: (a) the amount and position of substituent groups as sulfate (major), pyruvic acid ketals, methoxyl and glycosyl side-chain (4-O-methyl galactopyranosyl and/or xylosyl); (b) the ratio galactose/3,6-anhydrogalactose in the B-units; (c) the ratio d , l -galactoses and d , l -3,6-anhydrogalactoses also in the B-units, (d) the formation of diads and (e) the sequence of the diads in the linear backbone. Considering these variables it is not unexpected to find in the fractions studied at least 18 structural units producing highly complex structures. Structural studies carried out in two major fractions (S2S-3 and S2S-4) showed that these Galactans were formed mainly by β- d -galactopyranosyl 2-sulfate (20 and 11.9 mol %), β- d -galactopyranosyl 2-sulfate 4,6-O-(1′-carboxyethylidene) (8.9 and 6.0 mol %) and β- d -galactopyranosyl 2,6-sulfate (5.4 and 18.6 mol %), together with 3,6-anhydro-α- l -galactopyranosyl (11.4 and 7.3 mol %) and 3,6-anhydro-α- l -galactopyranosyl 2-sulfate (4.9 and 15.4 mol %) and minor quantities of 12–15 other structural units. Preparative alkaline treatment carried out on fraction (S2S-3) produced a quantitative formation of 3,6-anhydro α- l -galactopyranosyl units from precursor units (α- l -galactose 6-sulfate and α- l -galactose 2,6-sulfate). Kinetic studies on this 3,6-anhydro cyclization show a rate constant of 5.2 × 104 s−1 indicating diads of the type G→L6S/2,6S. Data from chemical, spectroscopic and kinetic studies suggest that, in S2S-3, the agaran block in the d , l -hybrid galactan is composed of the following diads: G(6R)→L6S/2,6S and G2S(P)(2,6S)→LA(2S)(2R)(2M) and the carrageenan block of G2S(P)→D(2S)(2,3S)(3S)(3,6S) in a molar ratio of agaran to carrageenan structures of ∼2:1.
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the system of sulfated Galactans from the red seaweed gymnogongrus torulosus phyllophoraceae rhodophyta location and structural analysis
Carbohydrate Polymers, 2008Co-Authors: José M. Estevez, Marina Ciancia, Alberto S. CerezoAbstract:Abstract Sulfated polysaccharides were localized in the cuticle, cortex and medulla of the gametophyte thallus, being more concentrated in the intercellular matrix than in the cell walls. During the water extraction sequence, a small percentage of galactan sulfates (5.1% of dry seaweed) with average low M r (6–11.4 kDa) were extracted at room temperature without disturbing the cellular arrangement, while sulfated Galactans of average medium M r (18–45 kDa) were obtained by further hot-water extractions (52.4% of dry seaweed), with diorganization of the tissue. The residue (40.0% of dry seaweed) still contained carrageenan-type (major) and agaran-type (minor) Galactans. Part of these Galactans was extracted with 8.4% LiCl solution in DMSO, from which “pure” κ/ι-carrageenans were isolated. Carrageenans and agarans were extracted in a ratio 1:0.5, showing the highest amount of agaran-structures for a carrageenophyte. The Galactans comprise alternating 4-sulfated (major) and non-sulfated (minor) 3-linked β- d -galactopyranose units, and 4-linked α-galactopyranose units with the following substitutions: (i) non-sulfated and 2-sulfated 3,6-anhydro-α- d -galactopyranose residues in the carrageenan-structures, which belong to the κ-family (κ/ι-carrageenans); (ii) 3-sulfated α- l -galactopyranose units and 2-sulfated 3,6-anhydro-α- l -galactopyranose residues in the agaran-structures. Alkaline treatment and alkaline dialysis of the main extracts gave “pure” κ/ι-carrageenans, showing that carrageenan molecules are extracted together with low M r agarans or agaran- dl -hybrids.
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The system of Galactans of the red seaweed, Kappaphycus alvarezii, with emphasis on its minor constituents
Carbohydrate research, 2004Co-Authors: José M. Estevez, Marina Ciancia, Alberto S. CerezoAbstract:The Galactans extracted with hot water from Kappaphycus alvarezii, after previous extraction at room temperature, are mainly composed of j-carrageenans (� 74%) and l-carrageenans (� 3%). However, a significant percentage of these Galactans (at least 14%) is composed of sulfated agarans and, possibly, agaran-type sulfated DL-hybrid Galactans. These agarans are partially sub- stituted on C-2 or C-4 or disubstituted on both positions of the b-D-galactose units and on C-3 or C-2 and C-3 of the a-L-galactose residues with sulfate groups or single stubs of b-D
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novel dl galactan hybrids from the red seaweed gymnogongrus torulosus are potent inhibitors of herpes simplex virus and dengue virus
Antiviral Chemistry & Chemotherapy, 2002Co-Authors: Carlos A Pujol, Marina Ciancia, José M. Estevez, Alberto S. Cerezo, Maria Josefina Carlucci, Elsa B. DamonteAbstract:A novel series of DL-galactan hybrids extracted from the red seaweed Gymnogongrus torulosus, was evaluated for its in vitro antiviral properties against herpes simplex virus type 2 (HSV-2) and dengue virus 2 (DEN-2). These compounds were very active against both viruses with inhibitory concentration 50% (IC50) values in the range 0.6–16 μg/ml for HSV-2 and 0.19–1.7 μg/ml for DEN-2, respectively, as determined in a virus plaque reduction assay in Vero cells. The DL-Galactans lacked of cytotoxic effects, on stationary as well as on actively dividing cells, and anticoagulant properties. Some of the compounds showed a variable level of direct inactivating effect on both virions, with virucidal concentration 50% values exceeding the IC50s obtained by plaque reduction assay. Full inhibitory activity was achieved when the Galactans were present during virus adsorption period, suggesting that the mode of action of these compounds is an interference in the binding of the surface envelope glycoprotein with the cell...
Ana Paula Valente - One of the best experts on this subject based on the ideXlab platform.
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Occurrence of sulfated Galactans in marine angiosperms: Evolutionary implications. Glycobiology 2005
2015Co-Authors: Rafael S. Aquino, Ana Paula Valente, Leonardo R Andrade, Ana M. L, Paulo A. S. Mour~aoAbstract:We report for the first time that marine angiosperms (seagrasses) possess sulfated polysaccharides, which are absent in terrestrial and freshwater plants. The structure of the sulfated polysaccharide from the seagrass Ruppia maritima was determined. It is a sulfated D-galactan com-posed of the following regular tetrasaccharide repeating unit: [3-b-D-Gal-2(OSO3)-1!4-a-D-Gal-1!4-a-D-Gal-1!3-b-D-Gal-4(OSO3)-1!]. Sulfated Galactans have been described previously in red algae and in marine inver-tebrates (ascidians and sea urchins). The sulfated galactan from the marine angiosperm has an intermediate structure when compared with the polysaccharides from these two other groups of organisms. Like marine invertebrate galac-tan, it expresses a regular repeating unit with a homo-genous sulfation pattern. However, seagrass galacta
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a preponderantly 4 sulfated 3 linked galactan from the green alga codium isthmocladum
Glycobiology, 2007Co-Authors: Eduardo H C Farias, Ana Paula Valente, Vitor H. Pomin, Helena B Nader, Hugo Alexandre Oliveira Rocha, Paulo A.s. MourãoAbstract:The green algae of the genus Codium have recently been demonstrated to be an important source of sulfated Galactans from the marine environment. Here, a sulfated galactan was isolated from the species Codium isthmocladum and its structure was studied by a combination of chemical analyses and NMR spectroscopy. Two fractions (SG 1, approximately 14 kDa, and SG 2, approximately 20 kDa) were derived from this highly polydisperse and heterogeneous polysaccharide. Both exhibited similar structures in (1)H 1D NMR spectra. The structural features of SG 2 and its desulfated derivative were analyzed by COSY, TOCSY, DEPT-HSQC, HSQC, and HMBC. This sulfated galactan is composed preponderantly of 4-sulfated, 3-linked beta-D-galactopyranosyl units. In minor amounts, it is sulfated and glycosylated at C-6. Pyruvate groups are also found, forming five-membered cyclic ketals as 3,4-O-(1'carboxy)-ethylidene-beta-D-galactose residues. A comparison of sulfated Galactans from different marine taxonomic groups revealed similar backbones of 3-beta-D-Galp-1.
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structure and anticoagulant activity of a sulfated galactan from the red alga gelidium crinale is there a specific structural requirement for the anticoagulant action
Carbohydrate Research, 2005Co-Authors: Maria G Pereira, Ana Paula Valente, Fabio R Melo, Norma Maria Barros Benevides, Marcia R S Melo, Paulo A.s. MourãoAbstract:Marine red algae are an abundant source of sulfated Galactans with potent anticoagulant activity. However, the specific structural motifs that confer biological activity remain to be elucidated. We have now isolated and purified a sulfated galactan from the marine red alga, Gellidium crinale. The structure of this polysaccharide was determined using NMR spectroscopy. It is composed of the repeating structure -4-alpha-Galp-(1-->3)-beta-Galp1--> but with a variable sulfation pattern. Clearly 15% of the total alpha-units are 2,3-di-sulfated and another 55% are 2-sulfated. No evidence for the occurrence of 3,6-anhydro alpha-galactose units was observed in the NMR spectra. We also compared the anticoagulant activity of this sulfated galactan with a polysaccharide from the species, Botryocladia occidentalis, with a similar saccharide chain but with higher amounts of 2,3-di-sulfated alpha-units. The sulfated galactan from G. crinale has a lower anticoagulant activity on a clotting assay when compared with the polysaccharide from B. occidentalis. When tested in assays using specific proteases and coagulation inhibitors, these two Galactans showed significant differences in their activity. They do not differ in thrombin inhibition mediated by antithrombin, but in assays where heparin cofactor II replaces antithrombin, the sulfated galactan from G. crinale requires a significantly higher concentration to achieve the same inhibitory effect as the polysaccharide from B. occidentalis. In contrast, when factor Xa instead of thrombin is used as the target protease, the sulfated galactan from G. crinale is a more potent anticoagulant. These observations suggest that the proportion and/or the distribution of 2,3-di-sulfated alpha-units along the galactan chain may be a critical structural motif to promote the interaction of the protease with specific protease and coagulation inhibitors.
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Occurrence of sulfated Galactans in marine angiosperms: evolutionary implications.
Glycobiology, 2004Co-Authors: Rafael S. Aquino, Ana Paula Valente, Leonardo R Andrade, Ana M. Landeira-fernandez, Paulo A.s. MourãoAbstract:We report for the first time that marine angiosperms (seagrasses) possess sulfated polysaccharides, which are absent in terrestrial and freshwater plants. The structure of the sulfated polysaccharide from the seagrass Ruppia maritima was determined. It is a sulfated D-galactan composed of the following regular tetrasaccharide repeating unit: [3-b-D-Gal-2(OSO3)-1!4-a-D-Gal-1!4-a-D-Gal1!3-b-D-Gal-4(OSO3)-1!]. Sulfated Galactans have been described previously in red algae and in marine invertebrates (ascidians and sea urchins). The sulfated galactan from the marine angiosperm has an intermediate structure when compared with the polysaccharides from these two other groups of organisms. Like marine invertebrate galactan, it expresses a regular repeating unit with a homogenous sulfation pattern. However, seagrass galactan contains the D-enantiomer of galactose instead of the L-isomer found in marine invertebrates. Like red algae, the marine angiosperm polysaccharide contains both a and b units of D-galactose; however, these units are not distributed in an alternating order, as in algal galactan. Sulfated galactan is localized in the plant cell walls, mostly in rhizomes and roots, indicative of a relationship with the absorption of nutrients and of a possible structural function. The occurrence of sulfated Galactans in marine organisms may be the result of physiological adaptations, which are not correlated with phylogenetic proximity. We suggest that convergent adaptation, due to environment pressure, may explain the occurrence of sulfated Galactans in many marine organisms.
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structure and anticoagulant activity of sulfated Galactans isolation of a unique sulfated galactan from the red algaebotryocladia occidentalis and comparison of its anticoagulant action with that of sulfated Galactans from invertebrates
Journal of Biological Chemistry, 2000Co-Authors: Ana Paula Valente, Mariana S. Pereira, Wladimir R L Farias, Paulo A.s. MourãoAbstract:Abstract We have characterized the structure of a sulfatedd-galactan from the red algae Botryocladia occidentalis. The following repeating structure (-4-α-d-Galp-1→3-β-d-Galp-1→) was found for this polysaccharide, but with a variable sulfation pattern. Clearly one-third of the total α-units are 2,3-di-O-sulfated and another one-third are 2-O-sulfated. The algal sulfated d-galactan has a potent anticoagulant activity (similar potency as unfractionated heparin) due to enhanced inhibition of thrombin and factor Xa by antithrombin and/or heparin cofactor II. We also extended the experiments to several sulfated polysaccharides from marine invertebrates with simple structures, composed of a single repeating structure. A 2-O- or 3-O-sulfatedl-galactan (as well as a 2-O-sulfatedl-fucan) has a weak anticoagulant action when compared with the potent action of the algal sulfated d-galactan. Possibly, the addition of two sulfate esters to a single α-galactose residue has an “amplifying effect” on the anticoagulant action, which cannot be totally ascribed to the increased charge density of the polymer. These results indicate that the wide diversity of polysaccharides from marine alga and invertebrates is a useful tool to elucidate structure/anticoagulant activity relationships.
