Formation of 1,5-lactones from 3-deoxy-d-manno-2-octulosonic acid derivatives.

Acylation of ammonium 3-deoxy-α-D-manno-2-octulopyranosonate (1a) leads to the formation of peracetylated 3-deoxy-α-D-manno-2-octulopyranosono- 1,5-lactones (3a,b). Theproposed structures were confirmed by independent syntheses. The 1,7-lactone was not formed even when only OH-7 was available for lactonisation.     

Large-Scale Synthesis of a Lewis b Tetrasaccharide Derivative,its Acrylamide Copolymer,and Related DI- and Trisaccharides for Use in Adhesion Inhibition Studies with Helicobacter Pylori.

ABSTRACT

The 2-aminoethyl glycoside of O-α-L-fucopyranosyl-(1→2)-O-β-D-galactopyranosyl-(1→3)-[O-α-L-fucopyranosyl-(1→4)]-2-acetamido-2-deoxy-β-D-glucopyranose (Lewis B tetrasaccharide) was synthesized on a large scale and acryloylated with acryloyl chloride. The obtained oligosaccharide 2-acrylamidoethyl glycoside was then copolymerized with acrylamide to form a water-soluble, high molecular weight polymer, suitable for use in adhesion inhibition studies with Helicobacter pylori. Also synthesized were the corresponding derivatives of O-α-L-fucopyranosyl-(1→2)-O-β-D-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-β-D-glucopyranose and O-β-L-fucopyranosyl-(1→2)-β-D-galactopyranose.

     

A new Kdo derivative for the synthesis of an inner-core disaccharide of lipopolysaccharides and lopooligosaccharides

Methyl (7,8-di-O-benzoyl-4,5-O-isopropylidene-3-deoxy-d-manno-2-oct-ulopyranoside)onate was found to be a useful new intermediate in the synthesis of an inner-core oligosaccharide of lipooligosaccharides and lipopolysaccharides produced by gram-negative bacteria. This intermediate could be converted to the corresponding glycosyl fluoride and 4,5-diol acceptor with ease. Syntheses of dimeric Kdo, O-(sodium 3-deoxy-α-d-manno-2-octuropyranosylonate)-(2-4)-sodium (allyl 3-deoxy-α-d-manno-2-octuropyranoside)onate, and O-(sodium 3-deoxy-α-d-manno-2-octuropyranosylonate)-(2-8)-sodium (allyl 3-deoxy-α-d-manno-2-octuropyranoside)onate were successfully demonstrated.     

Synthesis and conjugation of a sulfated disaccharide involved in the aggregation process of the marine sponge Microciona prolifera

The synthesis is reported of allyl (sodium 2-acetamido-2-deoxy-β-d-glucopyranosyl 3-sulfate)-(1→3)-α-l-fucopyranoside which represents an oligosaccharide fragment of the aggregation factor of the marine sponge Microciona prolifera. The title compound was obtained by coupling of 3-O-allyloxycarbonyl-2-deoxy-4,6-O-isopropylidene-2-phthalimido-β-d-glucopyranosyl trichloroacetimidate with allyl 2,4-di-O-benzoyl-α-l-fucopyranoside, followed by de-isopropylidenation, acetylation, de-allyloxycarbonylation, sulfation, de-acylation, and finally N-acetylation. The allyl glycoside was eventually converted into a 3-(2-aminoethylthio)propyl glycoside and then coupled to bovine serum albumin (BSA) using diethyl squarate as the bivalent linker, yielding 8 hapten molecules per molecule of BSA.     

Synthesis, characterization and dioxygen reactivity of copper(I) complexes with glycoligands

A new family of copper(I) complexes with "glycoligands" containing a central saccharide scaffold, with 2-picolyl ether groups or 2-picolylamine or N-imidazolylamine groups, has been prepared and characterized. For this purpose, the following tetradentate ligands have been synthesized: methyl 2,3-di-O-(2-picolyl)-alpha-D-lyxofuranoside (L1), 1,5-anhydro-2-deoxy-3,4-di-O-(2-picolyl)-d-galactitol (L2), 5-(amino-N-(2-salicyl))-5-deoxy-1,2-O-isopropylidene-3-O-(2-picolyl)-alpha-D-xylofuranose (L3), and 5-(amino-N-(2-salicyl))-5-deoxy-1,2-O-isopropylidene-3-O-(methylimidazol-2-yl)-alpha-D-xylofuranose (L4). The ligands and the complexes were characterized by elemental analysis, IR, 1H and 13C NMR spectroscopies, ESI mass spectrometry, and cyclic voltammetry. Collaterally with the experimental work, HF-DFT(B3LYP/6-31G*) computations were performed to obtain additional structural information. The Cu(I) complexes are found to be pentacoordinated. The redox properties and the O2-reactivity of the Cu(I)Ln complexes have been studied. Reactions of Cu(I) complexes with dioxygen in ethanol yield stable Cu(II) complexes as confirmed by UV-visible spectrophotometry and EPR spectroscopy.     

Synthesis of Chiral Spiroacetals from Carbohydrates

Chiral spiroacetals of the 1,7-dioxaspiro[5.5]undecane, 1,6-dioxaspiro[4.5]decane, and 1,6-dioxaspiro[4.4]nonane types have been prepared from carbohydrates in pyranose or furanose forms. The spirocyclization reaction has been accomplished from a conveniently homologated carbohydrate by an intramolecular hydrogen abstraction reaction promoted by alkoxy radicals. Thus, 2,3,4,6-tetra-O-benzyl-1-deoxy-1-(3'-hydroxypropyl)-alpha-D-glucopyranose (2) was photolyzed with visible light in the presence of (diacetoxyiodo)benzene and iodine to give a mixture of (1R)-(3) and (1S)-2,3,4,6-tetra-O-benzyl-1-deoxy-D-glucopyranose-1-spiro-2'-tetrahydrofuran (4). The photolysis of methyl 6-deoxy-6-(2'-hydroxyethyl)-2,3,4-tri-O-methyl-alpha-D-glucopyranoside (8) gave the isomeric spiroacetals methyl (5S)- (9) and (5R)-6-deoxy-5,2'-epoxy-6-ethyl-2,3,4-tri-O-methyl-alpha-D-glucopyranoside (10) in which the spirocenter is now located at C-5. The spiroacetals of the [5.5]undecane series: methyl (5R)- (19) and (5S)-6-deoxy-5,3'-epoxy-2,3,4-tri-O-methyl-6-propyl-beta-D-glucopyranoside (20) have been prepared starting from methyl 6-deoxy-6-(3'-hydroxypropyl)-2,3,4-tri-O-methyl-beta-D-glucopyranoside (18). The reaction has also been applied to hexofuranoses and 1-deoxy-1-(3'-hydroxypropyl)-2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranose (21) gave rise to (1S)- (22) and (1R)-1-deoxy-2,3:5,6-di-O-isopropylidene-D-mannofuranose-1-spiro-2'-tetrahydrofuran (23); and 1-deoxy-1-(4'-hydroxybutyl)-2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranose (28) to (1R)- (30) and (1S)-1-deoxy-2,3:5,6-di-O-isopropylidene-D-mannofuranose-1-spiro-2'-tetrahydropyran (32). Both spiroacetal enantiomers are formally available from the same carbohydrate.     

Synthesis of Substituted 3H-Indole-modified b-Cyclodextrin

The hydrophobic cavities of cyclodextrins and the inclusion with various organic molecules in the aqueous solution make them useful in chemical and biological activities1, one of which is the modified cyclodextrins acting as indicators of molecular recognition. Cyclodextrins, which are spectroscopically inert, can be converted into spectroscopically active compounds by modifing one or two of the hydroxy groups with appropriate chromophores, and used as molecular sensor due to the capability of…     

The 2-naphthylmethyl (NAP) group in carbohydrate synthesis: first total synthesis of the GlyCAM-1 oligosaccharide structures

Total syntheses of the GlyCAM-1 (glycosylation-dependent cell adhesion molecule-1) oligosaccharide structures: [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-(6-O-SO3Na)-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (1) and [alpha-NeuAc-(2 --> 3)-beta-Gal-(1 --> 4)-[alpha-Fuc-(1 --> 3)]-beta-GlcNAc-(1 --> 6)]-[alpha-NeuAc-(2 3)-beta-Gal-(1 --> 3)]-alpha-GalNAc-OMe (2) through a novel sialyl LewisX tetrasaccharide donor are described. Employing sequential glycosylation strategy, the starting trisaccharide was regio- and stereoselectively constructed through coupling of a disaccharide imidate with the monosaccharide acceptor phenyl-6-O-naphthylmethyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside with TMSOTf as a catalyst without affecting the SPh group. The novel sialyl Lewisx tetrasaccharide donor 3 was then obtained by alpha-L-fucosylation of trisaccharide acceptor with the 2,3,4-tri-O-benzyl-1-thio-beta-L-fucoside donor. The structure of the novel sialyl Lewisx tetrasaccharide was established by a combination of 2D DQF-COSY and 2D ROESY experiments. Target oligosaccharides 1 and 2 were eventually constructed through heptasaccharide which was obtained by regioselective assembly of advanced sialyl Lewisx tetrasaccharide donor 3 and a sialylated trisaccharide acceptor in a predictable and controlled manner. Finally, target heptasaccharides 1 and 2 were fully characterized by 2D DQF-COSY, 2D ROESY, HSQC, HMBC experiments and FAB mass spectroscopy.     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphin/Azodicarbonsäure-diäthylester. 3. Mitteilung [1]

Structural Modification on Partially Silylated Carbohydrates by Means of Triphenylphosphine/Diethyl Azodicarboxylate Reaction of methyl 2, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1a ) with triphenylphosphine (TPP)/diethyl azodicarboxylate (DEAD) and Ph₃P · HBr or methyl iodide yields methyl 3-bromo-2, 6-bis-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 3a ) and the corresponding 3-deoxy-3-iodo-alloside 3c (Scheme 1). By a similar way methyl 2, 6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2a ) can be converted to the 4-bromo-4-deoxy-galactoside 4a and the 4-deoxy-4-iodo-galactoside 4b . In the absence of an external nucleophile the sugar derivatives 1a and 2a react with TPP/DEAD to form the 3,4-anhydro-α- or -β-D -galactosides 5 and 6a , respectively, while methyl 4, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1b ) yields methyl 2,3-anhydro-4, 6-bis-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 7a , s. Scheme 2). Even the monosilylated sugar methyl 6-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2b ) can be transformed to methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 8 ; 56%) and 3,4-anhydro-α-D -alloside 9 (23%, s. Scheme 3). Reaction of 1c with TPP/DEAD/HN₃ leads to methyl 3-azido-6-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 10 ). The epoxides 7 and 8 were converted with NaN₃/NH₄Cl to the 2-azido-2-deoxy-altrosides 11 and 13 , respectively, and the 3-azido-3-deoxy-glucosides 12 and 14 , respectively (Scheme 4 and 5). Reaction of 7 and 8 with TPP/DEAD/HN₃ or p-nitrobenzoic acid afforded methyl 2,3-anhydro-4-azido-6-O-(t-butyldimethylsilyl)-4-deoxy-α- and -β-D -gulopyranoside ( 15 and 17 ), respectively, or methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-4-O-(p-nitrobenzoyl)-α- and -β-D -gulopyranoside ( 16 and 18 ), respectively, without any opening of the oxirane ring (s. Scheme 6). - The 2-acetamido-2-deoxy-glucosides 19a and 20a react with TPP/DEAD alone to form the corresponding methyl 2-acetamido-3,4-anhydro-6-O-(t-butyldimethylsilyl)-2-deoxy-galactopyranosides ( 21 and 22 ) in a yield of 80 and 85%, respectively (Scheme 7). With TPP/DEAD/HN₃ 20a is transformed to methyl 2-acetamido-3-azido-6-O-(t-butyldimethylsilyl)-2,3-didesoxy-β-D -allopyranoside ( 25 , Scheme 8). By this way methyl 2-acetamido-3,6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 19b ) yields methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-α-D -galactopyranoside ( 23 ; 16%) and the isomerized product methyl 2-acetamido-4,6-bis-O-(t-butyldimethylsilyl)-2-deoxy-α-D -glucopyranoside ( 19d ; 45%). Under the same conditions the disilylated methyl 2-acetamido-2-deoxy-glucoside 20b leads to methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-β-D -galactopyranoside ( 24 ). - All Structures were assigned by ¹H-NMR. analysis of the corresponding acetates.     

Photooxidation of 2'-deoxyguanosine 5'-monophosphate in aqueous solutions

Mass spectrometric and ultraviolet absorption spectral evidence are presented for the assignment of structures to three products detected in the reaction mixtures formed upon the photolysis of aqueous solutions of the nucleotide 2'-deoxyguanosine 5'-monophosphate (dGMP) with light of wavelengths >270 nm. The products for which structures are assigned are spiroiminodihydantoin 2'-deoxyribonucleotide (1), 2,2-diamino-4-([2-deoxy-5-monophosphate-beta-D-erythro-pentofuranosyl]amino)-5-(2H)-oxazolone (oxazolone 2'-deoxyribonucleotide, 2) and 2-amino-5-([2-deoxy-5-monophosphate-beta-D-erythro-pentofuranosyl]amino)-4H-imidazol-4-one (imidazolone 2'-deoxyribonucleotide, 3). These results, when combined with mechanistic data presented in an earlier communication, provide support for the proposal that the irradiation of dGMP with UVB light leads to the formation of singlet oxygen. The UV absorption spectral properties of the imidazolone make this product a reasonable candidate to rationalize the autosensitization of dGMP degradation reported in the earlier communication.     

Synthesis of 2′-deoxyribofuranosyl indole nucleosides related to the antibiotics SF-2140 and neosidomycin

The 2′-deoxyribofuranose analog of the naturally occurring antibiotics SF-2140 and neosidomycin were prepared by the direct glycosylation of the sodium salts of the appropriate indole derivatives, with 1-chloro-2- deoxy-3,5-di-O-p-toluoyl-α-D-erythropentofuranose ( 5 ). Thus, treatment of the sodium salt of 4-methoxy-1H- indol-3-ylacetonitrile ( 4a ) with 5 provided the blocked nucleoside, 4-methoxy-1-(2-deoxy-3,5-di-O-p-toluoyl-β- D-erythropentofuranosyl)-1H-indol-3-ylacetonitrile ( 6a ), which was treated with sodium methoxide to yield the SF-2140 analog, 4-methoxy-1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indol-3- ylacetonitrile ( 7a ). The neosidomycin analog ( 8 ) was prepared by treatment of the sodium salt of 1H-indol-3-ylacetonitrile ( 4b ) with 5 to obtain the blocked intermediate 1-(2-deoxy-3,5-di-O-p-toluoyl-β-D-erythropentofuranosyl) ?1H-indol-3-ylace-tonitrile ( 6b ) followed by sodium methoxide treatment to give 1-(2-deoxy-β-D-erythropentofuranosyl)-1H- indol-3-ylacetonitrile ( 7b ) and finally conversion of the nitrile function of 7b to provide 1-(2-deoxy-β-D- erythropentofuranosyl)-1H-indol-3-ylacetamide ( 8 ). In a similar manner, indole ( 9a ) and several other substituted indoles including 1H-indole-4-carbonitrile ( 9b ), 4-nitro-1H-indole ( 9c ), 4-chloro-1H-indole-2-carboxamide ( 9d ) and 4-chloro-1H-indole-2-carbonitrile ( 9e ) were each glycosylated and deprotected to provide 1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indole ( 11a ), 1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indole-4- carbonitrile ( 11b ), 4-nitro-1-(2-deoxy-β-D-erythropentofuranosyl)-1H-indole ( 11c ), 4-chloro-1-(2-deoxy-β-D- erythropentofuranosyl)-1H-indole-2-carboxamide ( 11d ) and 4-chloro-1-(2-deoxy-β-D-erythropentofuranosyl)- 1H-indole-2-carbonitrile ( 11e ), respectively. The 2′-deoxyadenosine analog in the indole ring system was prepared for the first time by reduction of the nitro group of 11c using palladium on carbon thus providing 4-amino-1-(2-deoxy-β-D-erythropentofuranosyl)- 1H-indole ( 16 , 1,3,7-trideaza-2′-deoxyadenosine).     

Synthesis and antitumor activities of glucan derivatives

A highly efficient and practical method for the preparation of β-d-Glc-(1→6)-[β-d-Glc-(1→3)]-β-d-Glc-(1→6)-β-d-Glc-(1→6)-[β-d-Glc-(1→3)]-d-Glc-OMe was described. A dendritic nonasaccharide was also synthesized. The antitumor activities of hexasaccharide, the dendrimer, their sulfated derivatives, together with the natural glucan-protein and the corresponding polysaccharide isolated from barmy mycelium of Grifola frondosa, were preliminarily investigated based on Sarcoma-180 studies in mice tests. Our results suggest that the sulfated branching oligosaccharide and natural glycoprotein have better antitumor activities comparing to the parent sugar residue (oligosaccharide or polysaccharide).     

Nucleotides. Part XXXIVSynthesis of Modified Oligomeric 2′–5′A Analogues: Potential Antiviral Agents

A series of new 2′–5′-oligonucleotide trimers carrying a 9-(2′,3′-anhydro-β-D -ribofuranosyl)-( 59 ), 9-(3′-deoxy-β-D -glycero-pent-3-enofuranosyl)-( 63 ), 9-(3′-azido-3′-deoxy-β-D -xylofuranosyl)-( 62 ), and 9-(3′-halo-3′-deoxy-β-D -xylofuranosyl)adenine ( 60 and 61 ) moiety at the 2′-terminal end have been synthesized via the phosphotriester method. The properly protected, modified monomeric building blocks ( 6 , 9 , 16 , 19 , 27 , 33 , 36 , 37 , and 43 ) were obtained, in general, by a sequence of reactions, introducing the protecting groups into the right positions. Their condensations with the intermediary dimeric 2′-terminal phosphodiesters 48 and 49 led to the fully protected 2′–5′-trimers 50–58 which were deblocked to form the free 2′–5′-trimers 59 – 63 . Easy elimination of HBr on deprotection did not allow to form the trimeric (3′-bromo-3′-deoxy-β-D -xylofuranosyl)adenine analogue but only 63 carrying an unsaturated sugar moiety instead. The newly synthesized compounds have been characterized by UV and NMR spectra as well as by elemental analysis.     

Synthesis and biological evaluation of Rhizobium sin-1 lipid A derivatives

A highly convergent strategy for the synthesis of several derivatives of the lipid A of Rhizobium sin-1 has been developed. The approach employed the advanced intermediate 3-O-acetyl-6-O-(3-O-acetyl-4,6-O-benzylidene-2-deoxy-2-phthalimido-beta-d-glucopyrano-syl)-2-azido-4-O-benzyl-2-deoxy-1-thio-alpha-d-glucopyranoside (5), which is protected in such a way that the anomeric center, the C-2 and C-2' amino groups, and the C-3 and C-3' hydroxyls can be selectively functionalized. The synthetic strategy was used for the preparation of 2-deoxy-6-O-[2-deoxy-3-O-[(R)-3-hydroxy-hexadecanoyl]-2-[(R)-3-octacosanoyloxy-hexadecan]amido-beta-d-glucopyranosyl]-2-[(R)-3-hydroxy-hexadecan]amido-3-O-[(R)-3-hydroxy-hexadecanoyl]-alpha-d-glucopyranose (11) and 2-deoxy-6-O-[2-deoxy-3-O-[(R)-3-hydroxy-hexadecanoyl]-2-[(R)-3-octacosanoyloxy-hexadecan]amido-beta-d-glucopyranosyl]-2-[(R)-3-hydroxy-hexadecan]amido-3-O-[(R)-3-hydroxy-hexadecanoyl]-d-glucono-1,5-lactone (13), which contain an unusual octacosanoic acid moiety and differ in the oxidation state of the anomeric center. The results of biological studies indicate that 11 and 13 lack the proinflammatory effects of Escherichia coli lipopolysaccharides (LPS). Furthermore, 13 emulated the ability of heterogeneous R. sin-1 LPS to antagonize enteric LPS, providing evidence for the critical role of the gluconolactone moiety of R. sin-1 LPS in mediating this antagonistic effect. Compound 13 is the first example of a lipid A derivative that is devoid of phosphate but possesses antagonistic properties, making it an attractive lead compound for development of a drug to use in the treatment of Gram-negative septicemia.     

海枫藤中C21甾体苷的分离和结构测定

从萝摩科植物海枫藤[Marsdenia officinalis Tsiang et P.T.Li.]的藤茎中分离得到四个C21甾体去氧糖苷(1)～(4). 通过化学降解和波谱技术, 确定它们的化学结构依次为: 12-O-桂皮酰基-20-O-乙酰基(20S)-孕甾烷-6-烯-3β,5α,8β,12β,14β, 17β,20-庚醇 3-O-甲基-6-去氧-β-D-阿洛吡喃糖基-(1→4)-β-D-夹竹桃吡喃糖基-(1→4)-β-D-磁麻吡喃糖苷(1), 12-O-桂皮酰基-20-O-乙酰基(20S)-孕甾烷-6-烯-3β,5α,8β,12β,14β,17β,20-庚醇3-O-β-D-葡萄吡喃糖基-(1→4)-3-O-甲基-6-去氧-β-D-阿洛吡喃糖基-(1→4)-β-D-磁麻吡喃糖基-(1→4)-β-D-磁麻吡喃糖苷(2), 12-O-桂皮酰基-20-O-乙酰基(20S)-孕甾烷-6- 烯-3β,5α,8β,12β,14β,17β,20-庚醇3-O-β-D-黄夹吡喃糖基-(1→4)-β-D-磁麻吡喃糖基-(1→4)-β-D-磁麻吡喃糖苷(3), 12-O-烟酰基-肉珊瑚苷元3-O-β-D-葡萄吡喃糖基-(1→4)-3-O-甲基-6-去氧-β-D-阿洛吡喃糖基-(1→4)-β-D-夹竹桃吡喃糖基- (1→4)-β-D-磁麻吡喃糖基-(1→4)-β-D-磁麻吡喃糖苷(4). 其中1和2为新化合物, 分别命名为haifengtenoside A, haifengtenoside B, 3和4分别为已知化合物mucronatoside H 和 hainaneosides A, 系首次从该植物中分离得到.     

Synthesis of the Carbohydrate Moiety of Glycoproteins from the Parasite Echinococcus granulosus and Their Antigenicity against Human Sera

Stereocontrolled syntheses of biotin-labeled oligosaccharide portions containing the carbohydrate moiety of glycoprotein from Echinococcus granulosus have been accomplished. Trisaccharide Galβ1-3Galβ1-3GalNAcα1-R (A), tetrasaccharide Galα1-4Galβ1-3Galβ1-3GalNAcα1-R (B), and pentasaccharide Galα1-4Galβ1-3Galβ1-3Galβ1-3GalNAcα1-R (C), (R = biotinylated probe) were synthesized by stepwise condensation and/or block synthesis by the use of 5-(methoxycarbonyl)pentyl 2-azido-4,6-O-benzylidene-2-deoxy-α-d-galactopyranoside as a common glycosyl acceptor. The synthesis of the tetrasaccharide and the pentasaccharide was improved from the viewpoint of reducing the number of synthetic steps and increasing the total yield by changing from stepwise condensation to block synthesis. Moreover, hexasaccharide E, which contains the oligosaccharide sequence which occurs in E. granulosus, was synthesized from trisaccharide D. We examined the antigenicity of these five oligosaccharides by an enzyme-linked immunosorbent assay (ELISA). Although compounds of C–E did not exhibit antigenicity against cystic echinococcosis (CE) patient sera, compounds B, D, and E showed good serodiagnostic potential for alveolar echinococcosis (AE).     

Xylose-DNA Containing the Four Natural Bases

Oligonucleotides containing (2′-deoxy-β-D -xylofuranosyl)guanine have been prepared. For this purpose 2-aminoadenosine ( 5 ) was synthesized and converted to 2′-deoxy-β-D -xyloguanosine ( 1 ). The related 2′-deoxy-β-D -xyloisoguanosine ( 3 ) and 2′-deoxy-β-D -xyloxanthosine ( 4 ) were also synthesized. Compound 1 was converted to the phosphonate and phosphoramidite building blocks 10 and 11 , respectively. The oligodeoxynucleotide (5′-3′)d(xG-xT-xA-xG-xA-xA-xT-xT-xC-xT-xA-xC-T) ( 18 ) formed a duplex with the same T_m as the parent (5′-3′)-(G-T-A-G-A-A-T-T-C-T-A-C) ( 19 ), but with an inverted CD spectrum.     

Synthesis and antigenic analysis of the BclA glycoprotein oligosaccharide from the Bacillus anthracis exosporium

The glycoprotein BclA is an important constituent of the exosporium of Bacillus anthracis spores. This glycoprotein is substituted with an oligosaccharide composed of a beta-L-rhamnoside substituted with the previously unknown terminal saccharide, 2-O-methyl-4-(3-hydroxy-3-methylbutanamido)-4,6-dideoxy-D-glucopyranose, also referred to as anthrose. Anthrose has not been found in spores of B. cereus and B. thuringiensis, making it a potential species-specific marker for B. anthracis. In order to study the antigenicity of anthrose, efficient syntheses of an anthrose-containing trisaccharide and a series of structurally related analogues were developed. The analogues lacked either the methyl ether at C-2 or contained modified C-4 amino functionalities of anthrose. The synthetic compounds were equipped with an aminopropyl spacer to facilitate conjugation to the carrier proteins mariculture Keyhole Limpet Hemocyanin (mcKLH) and bovine serum albumin (BSA). Serum antibodies of rabbits immunized with live or irradiated spores of B. anthracis Sterne 34F(2) were able to recognize the synthetic trisaccharide-mcKLH conjugate. The specificity of the interaction was confirmed by competitive inhibition with the free- and BSA-conjugated trisaccharides. Inhibition using the trisaccharide analogues demonstrated that the isovaleric acid moiety of anthrose is an important structural motif for antibody recognition. These data demonstrate that 1) anthrose is a specific antigenic determinant of the B. anthracis Sterne spore; 2) this antigen is presented to the immune system of rabbits receiving the anthrax live-spore vaccine; 3) synthetic analogues of the oligosaccharide retain the antigenic structure; and 4) the antigenic region is localized to specific terminal groups of the oligosaccharide. Collectively these data provide an important proof-of-concept step in the synthesis and development of spore-specific reagents for detection and targeting of non-protein structures in B. anthracis.     

Structure determination of glycopeptide of p-momorcharin

The structure of the N-linked oligosaccharide chain of β-momorcharin, a ribosome-inactivating protein from the seeds of Momordica charantia Linn (Cucurbitaceae) was determined. A glycopeptide liberated by pronase digestion of the glycoprotein was subjected to amino acid and neutral carbohydrate analysis to establish the composition of amino acid and sugar residues. The sequences and glycosylation linkages of the sugar and amino acid residues in the glycopeptide were determined as Manal-6(Xylβ1-2)-Manβ1-4GlcNAcβ1-4(Fucal-3)-GlcNAc-Asn-Leu by 2D-NMR spectroscopy and FAB-MS data.     

Fluorous tag method for the simultaneous synthesis of different kinds of glycolipids

A mixture of saccharide primers with partially fluorinated tails, 2-(perfluorooctyl)ethyl 4′-O-(β-d-galactopyranosyl)-β-d-glucopyranoside (Lac H2F8) and 6-(perfluorohexyl)hexyl 2′-acetamido-2′-deoxy-β-d-glucopyranoside (GN H6H6), were introduced to animal cells. The oligosaccharide of Lac H2F8 was elongated by cellular enzymes and gave a GM3-type oligosaccharide. On the other hand, GN H6F6 was galactosylated to afford a lactosamine derivative that was further sialylated. This research confirmed that simultaneous glycosylation processes took place for Lac H2F8 and GN H6F6 primers and that the presence of one did not prevent the glycosylation of the other from proceeding. Each primer was recognized independently and elongated sequentially by cellular enzymes. Significantly, the synthesis of glycolipids from a mixture of these artificial scaffolds did not prevent the synthesis of glycolipids from the natural precursor. The glycosyl transferases recognized both precursors resulting to simultaneous synthesis of glycolipids.