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Hiromune Ando

Publications and source records attributed to Hiromune Ando.

8 recordsLinked to original sources
PubMed2006

Extended applications of di-tert-butylsilylene-directed alpha-predominant galactosylation compatible with C2-participating groups toward the assembly of various glycosides.

The high versatility of di-tert-butylsilylene(DTBS)-directed alpha-predominant galactosylation have been extended to the construction of difficult glycan sequences. First, to investigate the compatibility of the alpha-predominant reaction with various glycosylation systems a variety of 4,6-O-DTBS-tethered galactosaminyl or galactosyl donors were synthesized efficiently, which have C2-participating groups with a wide variety of leaving groups such as alkylsulfenyl, halide, trichloroacetimidate groups. The results of the detailed examination of the glycosylation reaction using the glycosyl donors showed the wide scope of the 4,6-DTBS-directed alpha-galactosylation. In the next step, the stereoselective construction of alpha-GalN-Ser/Thr sequences was examined by employing the DTBS-directed glycosylation. As a result, various types of serine and threonine derivatives were glycosylated alpha-selectively, producing alpha-GalN-Ser/Thr sequences in high yields. Moreover, the DTBS-directed galactosylation was successfully applied for the synthesis of alpha-tetrasaccharyl-Ser segment of glycophorin A.

Journal Article↗
PubMed2006

Studies on the alpha-(1-->4)- and alpha-(1-->8)-fucosylation of sialic acid for the total assembly of the glycan portions of complex HPG-series gangliosides.

A synthetic study on alpha-(1-->4) and alpha-(1-->8)-fucosylation of sialic acid is reported, with the ultimate aim being the total assembly of the glycan portion of HPG-series gangliosides. In both types of fucosylations, the combination of a phenylthio fucosyl donor and a 1,5-lactamized acceptor provided high-yielding glycosylations to afford alpha-fucosyl-sialic acid sequences. The obtained alpha-Fucp-(1-->8)-NeupNAc glycan having a 1,5-lactam bridge has been successfully transformed into the corresponding glycosyl donor.

Carbohydrate Sequence↗
PubMed2006

Synthesis and enzymatic susceptibility of a series of novel GM2 analogs.

A series of GM2 analogs in which GM2 epitope was coupled to a variety of glycosyl lipids were designed and synthesized to investigate the mechanism of enzymatic hydrolysis of GM2 ganglioside. The coupling of N-Troc-protected sialic acid and p-methoxyphenyl galactoside acceptor gave the crystalline disaccharide, which was further coupled with galactosamine donor to give the desired GM2 epitope trisaccharide. After conversion into the corresponding glycosyl donor, the trisaccharide was coupled with galactose, glucose and artificial ceramide (B30) to give the final compounds. The result on hydrolysis of GM2 analogs indicates that GM2 activator protein requires one spacer sugar between GM2 epitope and the lipid moiety to assist the hydrolysis of the terminal GalNAc residue.

Enzymes↗
PubMed2005

Antioxidative compounds from the outer scales of onion.

Antioxidative compounds were isolated from the methanol extract of dry outer scales of onion (Allium cepa L.). Nine phenolic compounds (1-9) were finally obtained by reversed-phase high-performance liquid chromatography, and their structures were elucidated by NMR and mass spectrometry analyses. They were the six known compounds, protocatechuic acid (1), 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (2), quercetin 4'-O-beta-D-glucopyranoside (3), quercetin (5), 4'-O-beta-d-glucopyranoside of quercetin dimer (7), and quercetin dimer (8), and three novel compounds, condensation products of quercetin with protocatechuic acid (4), adduct of quercetin with quercetin 4'-O-beta-D-glucopyranoside (6), and quercetin trimer (9). These phenolic compounds were tested for their antioxidant properties using autoxidation of methyl linoleate in bulk phase or free radical initiated peroxidation of soybean phosphatidylcholine in liposomes. The flavonoid compounds having o-dihydroxy substituent in the B-ring were shown to be effective antioxidants against nonenzymic lipid peroxidation.

Antioxidants↗
PubMed2005

A facile method for beta-selenoglycoside synthesis using beta-p-methylbenzoyl selenoglycoside as the selenating unit.

[reaction: see text] The reaction between alpha-glycosyl bromides and potassium p-methylselenobenzoate yields beta-p-methylbenzoyl selenoglycosides. The acyl selenoglycosides were activated by the action of a secondary amine and Cs2CO3 to produce an anomeric selenolate anion, which reacted in situ with various electrophiles to yield novel selenoglycosides while retaining the anomeric stereochemistry.

Amines↗
PubMed2001

Solid-Phase Capture-Release Strategy Applied to Oligosaccharide Synthesis on a Soluble Polymer Support This work was supported in part by the Mizutani Foundation for Glycoscience (grant to Y.I.), the RIKEN Presidential Fund (grant to S.M.), and the Ministry of Education, Culture, Sports, Science and Technology (Grant-in-Aid for Scientific Research to S.M.). We thank Dr. Teiji Chihara and his staff for the elemental analyses, Ms. Yasuko Tanaka for her contribution at the exploratory stage of this work, and Ms. Akemi Takahashi for her technical assistance.

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Journal Article↗