Tsuyoshi Fujiwara

Chemical synthesis of the trisaccharide unit of the species-specific phenolic glycolipid from Mycobacterium leprae.

O-(3,6-Di-O-methyl-beta-D-glucopyranosyl)-(1----4)-O-(2,3-di-O-methyl- alpha-L-rhamnopyranosyl)-(1----2)-3-O-methyl-L-rhamnopyranose, the haptenic trisaccharide of the Mycobacterium leprae-specific phenolic glycolipid I (PGL-I) antigen, and related trisaccharides, were synthesized by allylation of O-2 of benzyl 4-O-benzyl-alpha-L-rhamnopyranoside using phase-transfer catalysis, methylation of the product, deallylation, and coupling to O-(2,4-di-O-acetyl-3,6-di-O-methyl-beta-D-glucopyranosyl)-(1----4)-2,3- di-O-methyl-L-rhamnopyranosyl bromide or related disaccharides. Anomeric mixtures of the trisaccharide derivatives were separated by preparative t.l.c., deacetylated, and hydrogenolyzed, to give the pure trisaccharides. It had already been demonstrated that only those trisaccharides containing an intact, terminal 3,6-di-O-methyl-beta-D-glucopyranosyl unit are effective in inhibiting the specific binding between PGL-I and anti-PGL-I immunoglobulin M antibodies in human lepromatous leprosy sera.

Chemical synthesis of disaccharides of the specific phenolic glycolipid antigens from Mycobacterium leprae and of related sugars

O-(3,6-Di-O-methyl-beta-D-glucopyranosyl)-(1----4)-2,3,-di-O-methyl-L -rhamnopyranose, which is the nonreducing disaccharide of the haptenic trisaccharide of the Mycobacterium leprae-specific, phenolic glycolipid I, O-(6-O-methyl-beta-D-glucopyranosyl)-(1----4)-2,3-di-O-methyl-L-rhamn opyranose, the nonreducing end of the specific, phenolic glycolipid III, and the nonhaptenic O-beta-(D-glucopyranosyl)-(1----4)-2,3-di-O-methyl-L-rhamnopyranose++ +, were synthesized in relatively good yield from 3-O-methyl-D-glucose, or D-glucose, and L-rhamnose via Koenigs-Knorr reactions. These disaccharides can be used as precursors in the synthesis of the trisaccharide unit of phenolic glycolipid I and of neoglycoconjugates suitable for the serodiagnosis of leprosy.

A new dialdose dianhydride

Abstract A new dialdose dianhydride derivative was obtained from an acid hydrolyzate of the water-soluble polysaccharide of wobaku wood by successive treatment with methanolic hydrogen chloride and acetic anhydride-pyridine. This compound was determined to be the 1,2′:1′,2-dianhydride of 3,4-di- O -acetyl-β- l -rhamnopyranose and methyl 3,4-di- O -acetyl-α- d -galactopyranuronate.

Synthesis of the 1,2′:1′,2-dianhydride of 3,4-di-O-acetyl-β-lrhamnopyranose and methyl 3,4-di-O-acetyl-α-D-galactopyranuronate from 2-O-(α-d-galactopyranosyluronic acid)-l-rhamnopyranose

Abstract The title compound was synthesized from 2- O -(α- d -galactopyranosyluronic acid)- l -rhamnopyranose ( 1 ), showing that the dianhydride is a cyclization product of 1 . Formation of the dianhydride reached a maximum within 4 h, in both 2.5 and 5% methanolic hydrogen chloride at 90°.

Synthesis of the trisaccharide-protein conjugate of the phenolic glycolipid of Mycobacterium tuberculosis for the serodiagnosis of tuberculosis.

The trisaccharide segment of the phenolic glycolipid (PGL) of Mycobacterium tuberculosis, 2-O-methyl-3-O-[3-O-(2,3,4-tri-O-methyl-alpha-L-fucopyranosyl)-alpha-L- rhamnopyranosyl]-alpha-L-rhamnopyranose, was synthesized in the form of the p-(2-methoxycarbonylethyl)phenyl glycoside by a stepwise condensation. 2,4-Di-O-benzyl-3-O-acetyl-alpha-L-rhamnopyranosyl chloride was coupled to p-(2-methoxycarbonylethyl)phenyl 4-O-benzyl-2-O-methyl-alpha-L-rhamnopyranoside in the presence of silver triflate, and 2,3,4-tri-O-methyl-alpha-L-rhamnopyranosyl chloride was then coupled to the deacetylated disaccharide by the same procedure. The trisaccharide was deblocked and coupled to BSA, giving the neoglycoconjugate TB-NT-P-BSA. TB-NT-P-BSA showed its possibility as a useful tool for the serodiagnosis of tuberculosis.

Physicochemical studies of the water-soluble polysaccharide of Phellodendron amurense Ruprecht☆

Abstract Purified, water-soluble polysaccharide of Phellodendron amurense Ruprecht (P-WSPS) was obtained in highly homogeneous state. The partial specific volume and intrinsic viscosity were, respectively, 0.56 and 11.68 dL/g. The S value and molecular weight depended strongly on the P-WSPS concentration, but extrapolation to infinite dilution gave S w,20 0 = 10.67 × 10 −13 s −1 and M 0 = 625 × 10 3 from velocity-sedimentation and equilibrium-sedimentation experiments, respectively, results that showed the highly branched structure of P-WSPS. The molecular weight calculated from the D 0 value (1.035 × 10 −7 ) and S 0 value agreed with that from the equilibrium-sedimentation experiment to within ∼±9%, showing that the diffusion method is useful for rapid estimation of molecular weight.

Chemical structure of the water-soluble polysaccharide of Phellodendron amurense Ruprecht☆

Abstract Purified, water-soluble polysaccharide (P-WSPS) of Phellodendron amurense Ruprecht consists of residues of l -rhamnose, l -arabinose, d -galactose, and d -galacturonic acid in the ratios of 29.26:22.45:31.17:17.10 (% by weight). G.l.c.m.s. analysis of methylated-reduced P-WSPS showed that it has a very complicated and highly branched structure, and consists mainly of (1→2)-linked l -rhamnose, (1→4)-linked l -arabinose, (1→4)-linked d -galactose, and (1→3)- and (1→4)-linked d -galacturonic acid. The presence of 2- O -(α- d -galactopyranosyluronic acid)- l -rhamnopyranose, 2- O -(β- d -galactopyranosyluronic acid)- l -arabinose, 4- O -(α- d -galactopyranosyluronic acid)- l -rhamnopyranose, and 4- O -(α- d -galactopyranosyluronic acid)- d -galactopyranose in the aldobiouronic acid fraction of the hydrolyzate of P-WSPS was also shown.

[3] Leprosy-specific neoglycoconjugates: Synthesis and application to serodiagnosis of leprosy

Publisher Summary This chapter discusses leprosy-specific neoglycoconjugates (NGCs). The first generation of NGCs were capable of specific recognition of anti-phenolic glycolipid I (PGL-I) antibodies in sera from patients with lepromatous leprosy. The chapter focuses on the NGCs synthesized in the laboratories of Brennan, Fujiwara and others, and Gigg and others. All of the syntheses, whether involving the entire trisaccharide unit or the outermost disaccharide, were accomplished by a stepwise glycosylation from the innermost residue that contained a glycosidically attached linker arm in configurationally correct form. Two basic strategies were used for the conjugation to protein, usually bovine serum albumin (BSA), through covalent linkage to the ɛ-amino groups of lysine residues. In one approach, the innermost glycosyl residue was assembled as a glycoside bearing an alkoxycarbonyl group for conversion via acylhydrazide to an acyl azide for coupling with lysine residues. Indirect enzyme linked immunosorbent assay (ELISA) is the method of choice for the application of the NGCs to the detection of anti-PGL-I antibodies in the serodiagnosis of leprosy.

Mass spectra of peracetates of some (1→2)-linked disaccharides

Abstract The mass spectra of two peracetylated disaccharides and the pentaacetate ( 1 ) of an aldobiouronic acid methyl ester, all having a (1→2)-linkage, were analyzed. The fragmentation pathway common to these compounds could be classified into four groups: ( 1 ) the aA type, which was the main pathway, ( 2 ) the abJ type, ( 3 ) the baA type, and ( 4 ) the baC type. The manner of fragmentation of peracetate 1 was similar to those of the disaccharides.

Variety of molecular species of the water-soluble polysaccharide of Phellodendron amurense Ruprecht

Abstract The molecular weight of the water-soluble polysaccharide of Phellodendron amurense Ruprecht was found to differ with the sample used. The difference is considered to be due to different degrees of degradation of the polysaccharide chains, together with oxidation of galactose to galacturonic acid residues.