The hex-5-enose degradation: zinc dust cleavage of 6-deoxy-6-iodo-α-<scp>D</scp>-galactopyranosidic linkages in methylated di- and trisaccharides

Aspinall, G. O.; Chatterjee, Delphi; Khondo, Lev

doi:10.1139/v84-464

Cited by 16 publications

(7 citation statements)

References 9 publications

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“…The major part of the above mixture was chromatographed on silica gel with dichloromethane-acetone (10: 1) to give samples of hex-I-enitol-terminated oligosaccharides TI and T2 whose structures were established from the 'Hmr and mass spectra and by methylated sugar analysis. The I ,2-dideoxy-5-0-methylhex-I-enitol triacetate formed from both oligosaccharides was identical (glc -mass spectrometry) to thc derivative reported in the preceding paper (8).…”

Section: Formation and Selective Cleavage Of6-deoxy-6-iodogalnctop)~rsupporting

confidence: 80%

The hex-5-enose degradation: cleavage of 6-deoxy-6-iodo-α-D-galactopyranosidic linkages in modified carboxyl-reduced methylated tragacanthic acid

Aspinall¹,

Puvanesarajah²

1984

Can. J. Chem.

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Reduction of galacturonic acid residues in permethylated tragacanthic acid, followed by transformation of the resulting galactose residues to those of 6-deoxy-6-iodogalactose, affords a modified polysaccharide which undergoes depolymerization by the Bernet-Vasella reaction on treatment with zinc dust. The two main products of depolymerization have been characterized, after reduction and acetylation, as 3,6-di-O-acetyl-l,2-dideoxy-5-O-methy1-4-0-(2,3,4-tri-0-methyl-~-~-xylopyranosyl)-L-lyxo-hex-I-enitol (1) and 0-(2,3,4-tri-0-methyl-a-L-fucopyranosyl)-(1 + 2)-0-(3,4-di-0-methyl-P-D-xylopyranosyl)-(I + 4)-3,6-di-0-acetyl-1 ,2-dideoxy-5-0-methyl-L-lyxo-hex-I-enitol (2). The fragmentation provides the first example of a chemical degradation of an a-D-galacturonan to furnish oligosaccharides in which side-chain units remain attached to modified galacturonic acid residues. Under the conditions used for the introduction of iodo substituents no evidence could be obtained for loss of 3-0-glycosyl substituents through side reactions involving solvolysis of 6-sulfonates.GERALD OLIVER ASPINALL et VELUPILLAI PUVANESARAJAH. Can. J. Chem. 62, 2736Chem. 62, (1984. La rkduction de rCsidus d'acide galacturonique dans de I'acide tragacanthique, suivie par une transformation des residus de galactose qui en rCsultent en dCsoxy-6 iodo-6 galactose, fournit un polysaccharide modifiC qui subit une dCpolymCrisation, sous l'influence de la poudre de zinc, par une rkaction de Bernet-Vasella. Apres la reduction et une acktylation, on a caractCrisC les deux produits principaux de la rkaction de dCpolymCrisation comme Ctant le di-0-acCtyl-3,6 didCsoxy-1,2 0-mCthyl(2). Cette fragmentation est le premier exemple d'une degradation chimique d'un a-D-galacturonane qui conduit A des oligosaccharides dans lesquels les unitCs des chaines IatCrales restent attach& A des residus d'acide galacturonique modifiCs.Sous les conditions utilisCes pour l'introduction des substituants iodo, on n'a pas pu observer de pertes de substituants 0-glycosyles-3 provenant de reactions de solvolyses secondaires des sulfonates-6.[Traduit par le journal]Methods developed recently for the selective cleavage of Bernet and Vasella (7) showed that the reaction of non-terminal glycisiduronic acid or glycosiduronamide-linkages in permethylated polysacharides have been based on structural modifications to yield altered sugar residues at which controlled depolymerization may be carried out with no detectable hydrolysis of normal glycosidic linkages. 'Thus treatment of glycosiduronic acids with lead tetraacetate effects decarboxylation-acetoxylation to give 5-acetoxypentopyranosides which may be cleaved reductively with sodium borohydride (1). Alternatively, Curtius rearrangements of glycosiduronamides furnish carbamates, 5-tert-butyloxycarbonylamino-or 5-benzyloxycarbonylamino-pentopyranosides, which may be cleaved respectively by mild acid treatment or hydrogenolysis (2). The procedures have been applied successfully to the fragmentation of both exterior (1, 2) and interior (3)...

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Section: Formation and Selective Cleavage Of6-deoxy-6-iodogalnctop)~rsupporting

confidence: 80%

The hex-5-enose degradation: cleavage of 6-deoxy-6-iodo-α-D-galactopyranosidic linkages in modified carboxyl-reduced methylated tragacanthic acid

Aspinall¹,

Puvanesarajah²

1984

Can. J. Chem.

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“…Acid lability of 4-0 -glycosylhex-5 -enoses under the conditions of the zinc degradation was observed previously (6). The disaccharide derivative 4a was characterized as a methyl glycoside in which the fragment ion at m / z 31 1 (7) from the trideuteriomethylated derivative 4b is characteristic of a (1 +4)-linked disaccharide, a conclusion supported by the identities of the hydrolysis products, 2,3,4*,6-…”

supporting

confidence: 64%

“…A reversal of these preferences was effected by partial acetolysis of the carboxyl-reduced polysaccharide, which permitted the isolation of a more random selection of oligosaccharides, but it was not always possible to distinguish between galactose residues originally present and those formed from the reduction of galacturonic acid units. The recently developed hex-5-enose degradation (6,7) provides an '~edicated to Professor D. E. Ryan on the occasion of his 65th birthday.…”

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confidence: 99%

The hex-5-enose degradation: cleavage of glycosiduronic acid linkages in modified methylated Sterculia gums

Aspinall¹,

Khondo²,

Williams³

1987

Can. J. Chem.

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Can. J. Chem. 65,2069 (1987. Reduction of uronic acid residues in permethylated polysaccharides from Sterculin urens and S. caudara gums, followed by transformation of the resulting hexose into 6-deoxy-6-iodohexose residues, affords modified polysaccharides that undergo depolymerization on treatment with zinc dust. The main products after reduction with sodium borohydride are hexenitolterminated oligosaccharides. Their structures have been assigned as members of a series of 0-[a-L-rhamnopyranosyll-(1 +3)-1,2-dideoxyhex-I-enitol derivatives, with and without attendant P-D-galactopyranosyl substituents, on the basis of nuclear magnetic resonance and mass spectral data and compositional analysis of trideuteriomethylated derivatives. The structures of the polysaccharides have been reassessed in the light of these and other experiments, and may now be formulated as containing a backbone of alternating 4-linked a-D-galacturonic acid and 2-linked a-L-rhamnopyranose residues bearing a minimum of three types of side chains attached at specific sites. Characterization of some of the degradation products provides evidence that limited degradation had occurred during methylation of the glycuronans.GERALD OLIVER ASPINALL, LEV KHONDO et BRUCE ALAN WILLIAMS. Can. J. Chem. 65,2069Chem. 65, (1987. La reduction de rtsidus d'acide uronique de polysaccharides permtthylts provenant de gommes de Sterculia urerls et de S. caudata, suivie d'une transformation de l'hexose qui en rtsulte en rtsidus dtoxy-6 iodo-6 hexose, fournit des polysaccharides modifits qui subissent une dtpolymerisation lorsqu'on les traite par de la poudre de zinc. Les produits principaux provenant d'une rtduction par le borohydrure de sodium sont des oligosaccharides se terminant par un hexknitol. En se basant sur des donnees de rtsonance magnttique nucltaire et de spectre d e masse ainsi que sur des analyses de composition des dtrivts trideuttromtthylts, on a attribut leurs structures aux membres d'une strie de dtrivts 0-[a-L-rhamnopyrannosyll-(1-3)-didtoxy-1,2 hexene-1 itols qui pouvaient aussi porter des groupements P-D-galactopyrannosyles. On a rttvalut les structures des polysaccharides a la lumiere de ces experiences ainsi que d'autres et on peut maintenant affirmer qu'elles contiennent une unite de base formte d'acide a-D-galacturonique lit par la position 4 qui alterne avec un rtsidu du a-L-rhamnopyrannose lit par la position 2; cette unite repetitive porte un minimum de trois types de chaines lattrales qui sont attachtes ides sites sptcifiques. La caractirisation de quelques produits de dtgradation fournit des donntes permettant d'affirmer qu'il s'est produit une degradation limitee au cours de la mtthylation des glycuronanes.[Traduit par la revue]Exudate gums from the Sterculia genus contain structurally similar, partially acetylated polysaccharides with residues of D-glucuronic acid, D-galacturonic acid, D-galactose, and L-rhamnose (1-5). The most detailed studies have been carried out on S . urens gum and led to the formulation of two structural regi...

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“…Region (B) of sterculia gum consists of branched trisaccharide units composed of β- d -galactose and α- d -galactouronic acid that are probably not present in repetitive sequences . α- d -Galactouronic acid is linked through (1−4 α) and (2−1 β) glycosidic linkage to β- d -galactose . These trisaccharide units are also interrupted by the rhamnogalacturonan regions at intervals .…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Implication for Cross-Linking in Sterculia-Based Hydrogels and Their Use in GIT Drug Delivery

Singh

Sharma

2009

Biomacromolecules

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Sterculia gum has been used as a therapeutic agent to cure diverticulitis. Hydrogels developed from sterculia gum to release the therapeutic agent will be double curing in action. Therefore, in the present study, an attempt has been made to synthesize novel hydrogels for the release of the model drug ciprofloxacin, a drug for diverticulitis. This paper discusses the synthesis, characterization, and in vitro release of ciprofloxacin from drug-loaded hydrogels in solutions of different pHs and simulated gastric and intestinal fluid. A non-Fickian diffusion mechanism has been observed for the release of the drug from drug-loaded hydrogels. This article also discusses the mechanistic implications of the cross-linking of sterculia gum with methacrylamide in the presence of N,N'-methylenebisacrylamide (N,N'-MBAAm) cross-linker.

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The hex-5-enose degradation: zinc dust cleavage of 6-deoxy-6-iodo-α-D-galactopyranosidic linkages in methylated di- and trisaccharides

Cited by 16 publications

References 9 publications

The hex-5-enose degradation: cleavage of 6-deoxy-6-iodo-α-D-galactopyranosidic linkages in modified carboxyl-reduced methylated tragacanthic acid

The hex-5-enose degradation: cleavage of 6-deoxy-6-iodo-α-D-galactopyranosidic linkages in modified carboxyl-reduced methylated tragacanthic acid

The hex-5-enose degradation: cleavage of glycosiduronic acid linkages in modified methylated Sterculia gums

Mechanistic Implication for Cross-Linking in Sterculia-Based Hydrogels and Their Use in GIT Drug Delivery

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