Trisaccharide Derivative Research Articles

Highly efficient oligosaccharide synthesis on water-soluble polymeric primers by recombinant glycosyltransferases immobilised on solid supports.

Recombinant beta-1,4-galactosyltranferase (beta 1,4-GalT) and alpha-2,6-sialytransferase (alpha 2,6-SiaT) immobilised covalently with activated Sepharose beads were employed for the practical synthesis of a trisaccharide derivative, Neu-5Ac alpha(2-->6)Gal beta(1-->4)GlcNAc beta-O-(CH2)6-NH2, on a water-soluble primer having GlcNAc residues through a alpha-chymotrypsin-sensitive linker.

Synthesis and structural studies of “branched” 2‐linked trisaccharides related to h‐type 2 blood group determinants

AbstractA series of fucosylated trisaccharides l‐Fuc‐(1→2)‐ß‐d‐Gal‐(1→4)‐ß‐X‐OMe (1‐6, X = d‐GlcNAc, d‐Qui (6‐deoxy‐Glc), d‐Xyl) related to H type 2 blood group determinant have been synthesized both as their α‐ and ß‐ L‐Fuc anomers together with the component disaccharide starting compounds (7‐11). The conformational properties of the trisaccharides together with their parent disaccharides have been investigated by NMR spectroscopy (proton and carbon chemical shifts and proton NOEs) in combination with computer modeling using the Monte Carlo approach and the HSEA force field using the GEGOP program with the main focus on the α‐linked fucose series.The series of compounds allow for the investigation of interaction between the sugar units in the—in principle—linear structures, which in practice behave as branched trisaccharides.The interaction between the terminal fucose unit and the unit at the reducing end has been probed by substitution of the bulky CH2OH group with CH3 and H substituents, respectively. Compounds with severe steric interactions can be identified by the non‐additivity of their carbon chemical shifts and subsequently confirmed by the detailed conformational assessment by NOEs and computer modeling. The most severe contacts arise in the GlcNAc and Qui trisaccharide series, whereas the Xyl‐containing trisaccharide derivatives only exhibit weak steric interaction as probed by the NMR parameters.

Unexpected stereochemical outcome of activated 4,6- O-benzylidene derivatives of the 2-deoxy-2-trichloroacetamido- d- galacto series in glycosylation reactions during the synthesis of a chondroitin 6-sulfate trisaccharide methyl glycoside

The synthesis of methyl (β- d-glucopyranosyluronic acid)-(1→3)-(2-acetamido-2-deoxy-6- O-sulfonato-β- d-galactopyranosyl)-(1→4)-(β- d-glucopyranosid)uronate trisodium salt, a chondroitin 6-sulfate trisaccharide derivative, is described. Loss of stereocontrol in glycosylation reactions involving activated 4,6- O-benzylidene derivatives of the 2-deoxy-2-trichloroacetamido- d- galacto series and d-glucuronic acid-derived acceptors was highlighted. This drawback was overcome through the use of phenyl 3,4,6-tri- O-acetyl-2-deoxy-1-thio-2-trichloroacetamido-β- d-galactopyranoside, which afforded the desired β-linked disaccharide derivative in high yield with an excellent stereoselectivity. This later was submitted to acid-catalyzed methanolysis, followed by benzylidenation, and condensed with methyl 2,3,4-tri- O-benzoyl-1- O-trichloroacetimidoyl-α- d-glucopyranuronate to afford the expected trisaccharide derivative. Subsequent transformation of the N-trichloroacetyl group into N-acetyl, mild acid hydrolysis, selective O-sulfonation at C-6 of the amino sugar moiety, and saponification afforded the target molecule as its sodium salt in high yield.

Synthetic studies on glycosphingolipids from protostomia phyla: synthesis of a glycosphingolipid analogue from the parasite Spirometra erinacei.

Novel neutral glycosphingolipids isolated from the plerocercoids of a tapeworm, Spirometra erinacei, may be expected to be involved in host-parasite interactions. We have synthesized this glycosphingolipid analogue containing 2-branched fatty alkyl residue in place of ceramide. Glycosylation of nonreducing-end trisaccharide derivative 15 with the reducing-end disaccharide derivative 17 in the presence of trimethylsilyl triflate (TMSOTf) gave the desired oligosaccharide derivative in good yield. The fully per-O-acylated 2-(trimethylsilyl)ethyl glycoside 19 was converted to glycosylimidate 20, which was condensed with 2-(tetradecyl)hexadecanol and subsequently deacylated to give the target glycosphingolipid analogue 22.

Convenient synthesis of Thr and Ser carrying the tumor associated sialyl-(2→3)-T antigen as building blocks for solid-phase glycopeptide synthesis

Sialyl-T antigens have been synthesized, conveniently and in high yield, by a block condensation approach. Glycosylation of the D-GalN3 derivative with the suitably protected sialyl-α-(2→3)-D-galactopyranosyl trichloroacetimidate by using trimethylsilyl trifluoromethanesulfonate (TMS-OTf) as a promoter in dichloromethane gave the trisaccharide in high yield. Cleavage of the tert-butyldimethylsilyl ether (TBDMS) at the anomeric position of the sialic acid containing trisaccharide derivative, using tetrabutylammonium fluoride (TBAF) in pyridine, occurred in very high yield. After conversion to the trichloroacetimidate coupling of the sialyl-containing trisaccharide derivative with Fmoc-Thr/Ser-OPfp, using silver trifluoromethanesulfonate (AgOTf) as a promoter in dichloromethane, gave the target building blocks in good yields.

Chemoenzymatic Synthesis of .ALPHA.(a.RAR.3)-linked Galactooligosaccharides.

Gal-α(1→3) -GalαpNP was regioselectively synthesized from para-nitrophenyl α-D-galactopyranoside (GalapNP) in 8.0% yield by the transglycosylation reaction, using α-galactosidase from Penicillium funiculosum. After conversion to an acetamidophenyl group, the para-nitrophenyl group was removed by using cerium ammonium nitrate (CAN). The heptaacetyl galactosyl disaccharide was converted to Gal-α (1→3) -Gal by deacetylation. To synthesize the trisaccharide, the heptaacetylgalactosyl disaccharide was converted to the trichloroacetimidate derivative, then coupled with a selectively protected GlcNAc derivative to give a trisaccharide derivative, which was then deprotected to provide Gal-α (1→3) -Gal-β(1→4) -GlcNAc.

Isolation and characterisation of disodium (4-amino-4-deoxy- β- l-arabinopyranosyl)-(1⃗8)-( d- glycero- α- d- talo-oct-2-ulopyranosylonate)-(2⃗4)-(methyl 3-deoxy- d- manno-oct-2-ulopyranosid)onate from the lipopolysaccharide of Burkholderia cepacia

A trisaccharide was isolated from the core oligosaccharide in the lipopolysaccharide (LPS) of Burkholderia cepacia GIFU 645 (ATCC 25416, type strain) by methanolysis followed by HPLC and saponification. It was identified by MS, methylation analysis and 1H and 13C NMR spectroscopy as disodium (4-amino-4-deoxy- β- l-arabinopyranosyl)-(1⃗8)-( d- glycero- α- d- talo-oct-2-ulopyranosylonate)-(2⃗4)-(methyl 3-deoxy- d- manno-oct-2-ulopyranosid)onate. In addition to the trisaccharide derivative, methanolysis gave dimethyl ( d- glycero- α- d- talo-oct-2-ulopyranosylonate)-(2⃗4)-(methyl 3-deoxy- d- manno-oct-2-ulopyranosid)onate in a relative proportion to the trisaccharide of 3:1, indicating a non-stoichiometric (∼25%) substitution of the octulosonic acid by 4-amino-4-deoxyarabinose in the LPS.

Synthesis of a Trisaccharide Related to the K-Antigen From Streptococcus Pneumoniae Type 29

Ethyl 2,3,5-tri-O-benzoyl-6-O-benzyl-1-thio-β-D-galactofuranoside was utilized as glycosyl donor for the synthesis of a disaccharide donor as a P-tolyl thioglycoside, which reacted with the suitable furanoside acceptor to afford the trisaccharide derivative related to the antigen of Streptococcus pneumoniae type 29 in the form of its methyl glycoside.

Use of dichlorophthaloyl (DCPhth) group as an amino protecting group in oligosaccharide synthesis

As an alternative to phthaloyl (Phth) group, 4,5-dichlorophthaloyl (DCPhth) group was investigated as an amino protecting group to prove it to be useful for the synthesis of β-glycosides of 2-acetamido-2-deoxy glucose (GlcNAc). DCPhth was introduced onto the C-2 nitrogen of glucosamine to give 2, which was further transformed into mono- and di- and trisaccharide derivatives which constitute basic structural units of asparagine linked glycoprotein oligosaccharides. DCPhth group proved to have sufficient stability under the standard conditions of protecting group manipulations (e.g. deacetylation, benzylation, benzylidenation), and Lewis acid-, silver salt- and iodonium ion-promoted glycosylation. Removal of DCPhth group was smoothly performed by using ethylenediamine in alcoholic solvent under substantially milder conditions required for deprotection of Phth.

Synthesis of a spacer-containing nonasaccharide fragment of Streptococcus pneumoniae 19F capsular polysaccharide

The nonasaccharide 1, representing three repeating units of the capsular polysaccharide from Streptococcus pneumoniae 19F, has been synthesized. The synthetic strategy is to first synthesize, by an AB + C route, trisaccharide derivative 14, having O-benzyl groups as persistent, and 1-O-allyl and 4″-O-acetyl groups as temporary, protecting groups. Then, specific replacement of the 1-O-allyl group with an α-H-phosphonate monoester gives trisaccharide 17, which is coupled to a spacer. The obtained derivative 18 is then extended from the 4″ end in a stepwise fashion to give compound 20, using trisaccharide 17 and solution-phase H-phosphonate chemistry. Finally, removal of the persistent O-protecting groups gives the nonasaccharide 1.

Acceptor hydroxyl group mapping for calf thymus α-(1 → 3) - galactosyltransferase and enzymatic synthesis of [formula omitted][formula omitted] analogs

The epitope of the acceptor substrate for α-(1 → 3)-galactosyltransferase from calf thymus has been mapped by using a series of mono-deoxygenated and mono- O-alkylated Type II (β- d- Galp-(1 → 4)-β- d- Glcp NAc) disaccharides. The 4-OH group of the β- d-galactopyranosyl residue is a key polar group essential for glycosyl transfer, tolerating neither deoxygenation nor O-alkylation. Substitution at positions 6 and 6′ by a variety of polar alkyl substituents was readily tolerated, allowing the preparative enzymatic synthesis of a series of trisaccharide derivatives carrying polar substituents on each of these hydroxyl groups. These new analogs are potential inhibitors of Clostridium difficile toxin A and of a human anti-α-Gal antibody.

Synthesis of Protected Hexp‐(1 → 4)‐β‐D‐GlcpNAc‐(1 → 2)‐α‐D‐Manp‐(1 → O)(CH2)7CH3 sequences (hex = β‐D‐Glc, 4‐deoxy‐4‐fluoro‐β‐D‐Gal, or 4‐deoxy‐β‐D‐Gal) Using a Glc–GlcNPhth Donor, Eventually Fluorinated or Deoxygenated at the Oligosaccharide Level

AbstractThree trisaccharide derivatives of the type β‐D‐Hexp‐(1 → 4)‐β‐D‐GlcpNAc(1 → 2)‐α‐D‐Manp‐(1 → O)(CH2)7CH3 have been synthesized, with Hex being either glucose (15), 4‐deoxy‐4‐fluorogalactose (20), or 4‐deoxygalactose (27). These trisaccharides have been designed for the study of the acceptor specificity of glycosyltransferases involved in termination of N‐acetyllactosamine‐type N‐glycans. Allyl (2‐O‐acetyl‐3,6‐di‐O‐benzyl‐β‐D‐glucopyranosyl)‐(1 → 4)‐3,6‐di‐O‐benzyl‐2‐deoxy‐2‐phthalimido‐β‐D‐glucopyranoside (10) was synthesized by condensation of 2,4,6‐tri‐O‐acetyl‐3‐O‐benzyl‐α‐D‐glucosypanosyl trichloroacetimidate with allyl 3,6‐di‐O‐benzyl‐2‐deoxy‐2‐phthalimido‐β‐D‐glucopyranoside, followed by 4′,6′‐de‐O‐acetylation, 4′,6′‐O‐benzylidenation (8), and specific acetal ring opening. Acetylation or inverted fluorination of 10, followed by deallylation and imidation, gave suitable disaccharide donors which were each condensed with octyl 3,4,6‐tri‐O‐benzyl‐α‐D‐mannopyranoside (14) to afford the fully protected trisaccharides 15 and 20. Deallylation and imidation of 8, followed by coupling to 14 and subsequent specific acetal ring opening, triflation, halogenation, and reductive dehalogenation gave the protected 4″‐deoxytrisaccharide.

Chemical and chemo-enzymatic synthesis of the [formula omitted] element that is part of N-linked carbohydrate chains of human lutropin

In the framework of a project aimed at the elucidation of the nature of the functional importance of the N-glycosylation of the α-subunit of the glycoprotein hormones human lutropin and human chorionic gonadotropin, the structural element α- Neu p 5Ac-(2 → 6)-β- d-Gal p NAc-(1 → 4)-β- d-Glc p NAc-(1 → 2)-α- d-Man p , which is part of the carbohydrate chains of human lutropin, has been prepared by chemical and chemo-enzymatic synthesis in the form of its propyl glycoside. Condensation of 4-O- acetyl-3,6-di-O- benzyl-2-deoxy-2-phthalimido-α/β- d-glucopyranosyl trichloroacetimidate with allyl 3,4,6-tri-O- benzyl-α- d-mannopyranoside gave after deacetylation allyl ( 3,6-di-O- benzyl-2-deoxy-2-phthalimido-β- d-glucopyranosyl)-(1 → 2)-3,4,6-tri -O- benzyl-α- d-mannopyranoside . Ethyl 3-O- benzyl-2-deoxy-2-phthalimido-1-thio-β- d-glucopyranoside was converted into the galacto-derivative ethyl 4,6-di-O- acetyl-3-O- benzyl-2-deoxy-2-phthalimido-1-thio-β- d-galactopyranoside via an oxidation-reduction route, as well as via S N2-type substitution with acetate. The use of this galacto thioglycoside, after its conversion into the corresponding bromide, as GalN donor for condensation with the mentioned disaccharide derivative yielded after deacetylation allyl (3-O- benzyl-2-deoxy-2-phthalimido-β- d-galactopyranosyl)-(1 → 4)-(3,6-di -O- benzyl-2-deoxy-2-phthalimido-β- d-glucopyranosyl)-(1 → 2)-3,4,6-tri -O- benzyl-α- d-mannopyranoside . Methylsulfenyl bromide-silver triflate promoted sialylation of this trisaccharide derivative with O- ethyl S- [methyl(5-acetamido-4,7,8,9-tetra-O- acetyl-3,5-dideoxy- d -glycero-α- d -galacto- non-2-ulopyranosyl)onate] dithiocarbonate and subsequent deprotection resulted into the aimed tetrasaccharide structural element. Alternatively, this compound was prepared via a block synthesis, which, however, was not superior to the linear strategy. Finally, a stereoselective sialylation of synthetically prepared β- d-Gal p NAc-(1 → 4)-β- d-Glc p NAc-(1 → 2)-α- d-Man p- (1 → O)CH 2CH 2CH 3 with CMP-Neu5Ac and rat liver α-2,6-sialyltransferase was accomplished affording the same tetrasaccharide structural element.

Syntheses of Modified Carbohydrates with Glycosidases: Stereo- and Regiospecific Syntheses of Lactosamine Derivatives and Related Compounds1

Different lactosamine derivatives, modified in the 2-N- and anomeric positions and suitable as intermediates for synthesis of Lewis-x and related compounds, were prepared with high specificity on a multigram scale directly from lactose, employing different D-glucosamine derivatives as acceptors and the abundant β-D-galactosidase from Bullera singularis as catalyst. Thus, methyl O-β-D-galactopyranosyl-(1→4)-2-azido-2-deoxy-β-D-glucopyranoside, ethyl O-β-D-galactopyranosyl-(1→4)-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside and ethyl O-β-D-galactopyranosyl-(1→4)-2-deoxy-2-(2,2,2-trichloroethoxycarbonylamino)-1-thio-β-D-glucopyranoside were formed in 20-40 % yield as calculated based on added acceptor. The 2-phthalimido derivative was isolated in crystalline form without chromatography (extraction/crystallization procedure). The trisaccharide derivative ethyl O-β-D-galactopyranosyl-(1→4)-O-β-D-galactopyranosyl-(1→4)-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside was also isolated. The corresponding cellobiosamine derivatives were similarly obtained from cellobiose using the same type of catalyst and acceptors. The β-D-galactosidase from bovine testes was found to catalyze the highly specific formation of the β(1→6)-linked derivative ethyl O-β-D-galactopyranosyl-(1→6)-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside from lactose and ethyl 2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside. Ethyl O-α-L-fucopyranosyl-(1→4)-2-amino-6-O-benzyl-2-deoxy-1-thio-β-D-glucopyranoside, suitable as an intermediate for preparation of Lewis-a and related compounds, was obtained from p-nitrophenyl α-L-fucopyranoside and 2-amino-6-O-benzyl-2-deoxy-1-thio-β-D-glucopyranoside, employing α-L-fucosidase from bovine testes as catalyst. 1. Presented at the XVIIIth International Carbohydrate Symposium, Milan, Italy, July 21-26, 1996.

ChemInform Abstract: Glycosidase‐Catalyzed Synthesis of Di‐ and Trisaccharide Derivatives Related to Antigens Involved in the Hyperacute Rejection of Xenotransplants.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of two analogues of the Sd a determinant. Replacement of the sialic acid residue by a sulfate or a carboxymethyl group

Two analogues of the Sd a determinant tetrasaccharide have been synthesized in order to investigate the physiological role of this carbohydrate moiety. These saccharides, having two different anionic substitutes for the sialic acid residue, are: β- d-Gal p NAc-(1 → 4)-3-O- SO 3H -β- d-Gal p-(1 → 4)-β- d-Glc p NAc-(1 → O)( CH 2 ) 5NH 2 and β- d-Gal p NAc-(1 → 4)-3-O- CH 2COOH -β- d-Gal p-(1 → 4)-β- d-Glc p NAc-(1 → 0) (CH 2) 5NH 2 . 5-Azidopentyl (2,6- di-O- benzyl-β- d-galactopyranosyl )-(1 → 4)-3,6- di-O- benzyl-2- deoxy-2- phthalimido-β- d-glucopyranoside served as a general building block. The trisaccharides were obtained after prior selective derivatization of HO-3′ of the disaccharide derivative via a dibutyltin oxide mediated reaction, followed by coupling at HO-4′ with 3,4,6- tri-O- acetyl-2- deoxy-2- phthalimido-β- d- galactopyranosyl trichloroacetimidate, and processing of the formed trisaccharide derivatives into their free forms. Two analogues of the Sd a determinant tetrasaccharide have been synthesized aimed at the investigation of the physiological role of this carbohydrate moiety. These saccharides, having two different anionic substitutes for the sialic acid residue, are; β- d-Gal p NAC-(1 → 4)-3-O- SO 3H -β- d-Gal p-(1 → 4)-β- d-Glc p NAC-(1 → O) (CH 2) 5NH 2 and β- d-Gal p NAC-(1 → 4)-3-O- CH 2COOH -β- d-Gal p-(1 → 4)-β- d-Glc p NAC-(1 → O) (CH 2) 5NH 2 .

Glycosidase-catalysed synthesis of di- and trisaccharide derivatives related to antigens involved in the hyperacure rejection of xenotransplants

A convenient enzymatic procedure, suitable for large scale preparation of the β-thioethyl 2-N-Teoc-derivative of Galα1–3Galβ1–4GlcNAc, is described (Teoc = 2,2,2-trichloroethoxycarbonyl). β-D-Galactosidase from Bullera singularis was used for the specific synthesis of Galβ1–4GlcNTeocβ-SEt from lactose and D-GlcNTeocβ-SEt. α-D-Galactosidase from coffee beans was used for the stereo-specific and highly regioselective preparation of Galα1–3Galβ1–4GlcNTeocβ-SEt, employing D-Galα-OPhNO 2-p as glycosyl donor and Galβ1–4GlcNTeocβ-SEt as acceptor.

Exploring the substrate specificity of sialyltransferases

Abstract

Formula omitted] derivatives

A family of [ 6-O-(1,2:3,4- di-O- isopropylidene-α- d-galactopyranosyl)methyl]tin species Ph n Sn(CH 2OR) 4− n ( 1n = 1–3 ), Ph n Me 3−n Sn(CH 2 OR) ( 2n = 0–3) and Bu 3SnCH 2OR ( 3) have been prepared from 1,2:3,4- di-O- isopropylidene-α- d-galactopyranose (ROH) and the iodomethylin compounds Ph n Sn(CH 2I) 4− n ( n = 1–3), Ph n Me 3− n SnCh 2I ( n = 1–3 and Bu 3SnCH 2I. The pyranose rings in these mono-, di- and trisaccharide derivatives, as well as in IPh n Sn(CH 2 OR) 3−n ( 4n = 0–2 ) and IPh n Me 2−n Sn(CH 2 OR) ( 5n = 0, 1 ), have similar twist-boat conformations in solution. The solution δ 119Sn NMR values for the series ( 1n = 1–4 ) and 4n = 1–3 )do not vary linearly with n. The X-ray diffraction study of ( 4n = 1 ) at 120 K revealed that only one of the sugar moieties acts as a C, O-bidentate ligand, via its pyranose ring oxygen. The tin centre in solid ( 4n = 1 ) is five-coordinate and has a trigonal bipyramidal geometry: the SnO and SnI bond lengths are 2.759(5) and 2.790 Å respectively, with ISnO valency angle of 173.591)°. As indicated by the solid state solution δ 119Sn values (−177.8 and −130.7 ppm respectively), the solid state structure of ( 4n = 1 ) does not survive on dissolution. The two pyranose rings in solid ( 4n = 1 ) have similar conformations (intermediate between screw-boat °S 5 and the twist-boat forms °T 2 with deviations in the direction of the boat-form B 2,5). Compound ( 1n = 3 ) undergoes transmetallation with PhLi to give LiCH 2OR, which was trapped as the triphenylgermanium derivative Ph 3GeCH 2OR.

2-Deoxy-2-trichloroacetamido-D-glucopyranose derivatives in oligosaccharide synthesis: from hyaluronic acid to chondroitin 4-sulfate trisaccharides

Suitably protected derivatives of phenyl 2-deoxy-1-thio-2-trichloroacetamido-β-D-glucopyranoside, 6, 15 and 16, a new class of glycosyl donors, were tested in the reaction with sugar acceptors of low reactivity (i.e. the methyl uronate 2). This methodology was applied to the stereocontrolled and high-yielding construction of the hyaluronic acid trisaccharide derivative 26. Selective inversion of configuration at C-4 of the central D-glucosamine unit, transformation of the N-trichloroacetyl group into N-acetyl, O-sulfation, and final deprotection afforded the corresponding chondroitin 4-sulfate trisaccharide derivative 30 in high yield.