Structural analysis of Gigartina pistillata carrageenans (Gigartinaceae, Rhodophyta)

Amimi, Abdellah; Mouradi, Aziza; Givernaud, Thierry; Chiadmi, Nadia; Lahaye, Marc

doi:10.1016/s0008-6215(01)00152-5

Cited by 25 publications

(21 citation statements)

References 29 publications

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“…The synthesis of β-thiophenyl 4-DP donor 2 was achieved by converting thiophenyl 4,6-anisylidene-β- d -glucopyranoside 21 into diol 1 followed by chemoselective oxidation to glucuronic acid (GlcA) using bisacetoxyiodobenzene (BAIB) and catalytic (tetramethylpiperidin-1-yl)oxyl (TEMPO; Scheme 1). 22,23 BAIB/TEMPO oxidation is highly selective for primary alcohols and does not react with the anomeric sulfide.…”

Section: Resultsmentioning

confidence: 99%

“…26 The glycosyl donor was prepared from β-thiophenyl 4,6-anisylidene glucopyranoside 21 by treatment with Bu 2 SnO in toluene with azeotropic distillation followed by regioselective 3- O -benzylation of the intermediate stannylidene acetal and 2- O -benzoylation to produce donor 20 in high overall yield (Scheme 4). The glycosyl acceptor was prepared from a known glucosamine derivative 36 in several steps: (i) deprotection of the C2 amine followed by its coversion to an azide by diazotransfer, 37 (ii) regioselective reductive cleavage of the anisylidene acetal using Bu 2 BOTf and BH 3 at 0 °C to produce a 4- O - p -methoxybenzyl (PMB)-protected thioglucosamine, 38 (iii) protection of the C3 and C6 hydroxyls as SEM and TBDPS ethers, respectively, and (iv) oxidative cleavage of the 4- O -PMB ether to produce acceptor 21 .…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Reactivity of 4′-Deoxypentenosyl Disaccharides

et al. 2014

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4-Deoxypentenosides (4-DPs) are versatile synthons for rare or higher-order pyranosides, and they provide an entry for structural diversification at the C5 position. Previous studies have shown that 4-DPs undergo stereocontrolled DMDO oxidation; subsequent epoxide ring-openings with various nucleophiles can proceed with both anti or syn selectivity. Here, we report the synthesis of α- and β-linked 4′-deoxypentenosyl (4′-DP) disaccharides, and we investigate their post-glycosylational C5′ additions using the DMDO oxidation/ring-opening sequence. The α-linked 4′-DP disaccharides were synthesized by coupling thiophenyl 4-DP donors with glycosyl acceptors using BSP/Tf2O activation, whereas β-linked 4′-DP disaccharides were generated by the decarboxylative elimination of glucuronyl disaccharides under microwave conditions. Both α- and β-linked 4′-DP disaccharides could be epoxidized with high stereoselectivity using DMDO. In some cases, the α-epoxypentenosides could be successfully converted into terminal l-iduronic acids via the syn addition of 2-furylzinc bromide. These studies support a novel approach to oligosaccharide synthesis, in which the stereochemical configuration of the terminal 4′-DP unit is established at a post-glycosylative stage.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis and Reactivity of 4′-Deoxypentenosyl Disaccharides

et al. 2014

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“…The list of studied species includes C. crispus, Gigartina alveata, G. clavifera, G. decipiens, G. pistillata, G. skottsbergii, Gymnogongrus torulosus, S. crispata, S. atropurpurea and several commercial and underutilised species collected from the occidental Portuguese coast. 8,[10][11][12][16][17][18][19][20][21][22][23][24] Although the functional properties in dairy applications have been studied for j/i-hybrids extracted from specific species, no systematic analysis of the j/i-hybrids has been reported. Most of the studies mentioned above started from a certain seaweed species and studied the functional properties of the carrageenans extracted.…”

Section: Introductionmentioning

confidence: 99%

The structure of κ/ι-hybrid carrageenans II. Coil–helix transition as a function of chain composition

Velde

Antipova

Rollema

et al. 2005

Carbohydrate Research

104

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This paper describes the effect of the kappa/iota-ratio on the physical properties of kappa/iota-hybrid carrageenans (synonyms: kappa-2, kappa-2, weak kappa, weak gelling kappa). To this end, a series of kappa/iota-hybrid carrageenans ranging from almost homopolymeric kappa-carrageenan (98 mol-% kappa-units) to almost homopolymeric-carrageenan (99 mol-% iota-units) have been extracted from selected species of marine red algae (Rhodophyta). The kappa/iota-ratio of these kappa/iota-hybrids was determined by NMR spectroscopy. Their rheological properties were determined by small deformation oscillatory rheology. The gel strength (storage modulus, G') of the kappa/iota-hybrids decreases with decreasing kappa-content. On the other hand, the gelation temperature of the kappa-rich kappa/iota-hybrids is independent of their composition. This allows one to control the gel strength independent of the gelation or melting temperature. The conformational order-disorder transition of the kappa/iota-hybrids was studied using optical rotation and high-sensitivity differential scanning calorimetry. High-sensitivity DSC showed that the total transition enthalpy of the kappa/iota-hybrids goes through a minimum at 60 mol-% kappa-units, whereas for the mixture of kappa- and iota-carrageenan, the total transition enthalpy is a linear function of the composition. With respect to the ordering capability, the kappa/iota-hybrid carrageenans seem to behave as random block copolymers with length sequence distributions truncated from the side of the small lengths. Intrinsic thermodynamic properties (e.g., transition temperature and enthalpy) of kappa- and iota-sequences in these copolymers are close to those of their parent homopolymers. The critical sequence length for kappa-sequences is 2-fold of that for iota-sequences.

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“…The alga was washed thoroughly with tap water and galactans were extracted according to Amimi et al (2001). The alga was extracted with deionised water (1.5 L) under agitation for 3 h at 95 • C. The aqueous phase was clarified by passing through a nylon cloth, and then precipitated in 2.5 volumes of isopropanol, filtered and dried at room temperature (yield 38%).…”

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confidence: 99%

Note: Characterisation of furcellaran samples from Estonian Furcellaria lumbricalis (Rhodophyta)

Laos

Ring

2005

J Appl Phycol

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The structure of furcellarans obtained from red algae Furcellaria lumbricalis collected in Estonia was determined. Native and alkali-modified furcellarans were examined by gas chromatography/mass spectrometry (GC/MS), and 13 C-nuclear magnetic resonance spectroscopy (NMR) and were compared with commercial furcellaran (FMC Food Ingredients). The polysaccharide preparation consisted mainly of (1→3) linked β-D-galactopyranose, (1→4) linked 3,6-anhydro-α-D-galactopyranose and (1→3) linked β-D-galactopyranose 4-sulphate. Alkaline treatment removed the sulphate precursor sequences with formation of 3,6-anhydrogalactose that improved the furcellaran gelling ability.

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Structural analysis of Gigartina pistillata carrageenans (Gigartinaceae, Rhodophyta)

Cited by 25 publications

References 29 publications

Synthesis and Reactivity of 4′-Deoxypentenosyl Disaccharides

Synthesis and Reactivity of 4′-Deoxypentenosyl Disaccharides

The structure of κ/ι-hybrid carrageenans II. Coil–helix transition as a function of chain composition

Note: Characterisation of furcellaran samples from Estonian Furcellaria lumbricalis (Rhodophyta)

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