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Abstract: An efficient synthesis of a series of carbosilane dendrimers uniformly functionalized with α-thioglycoside of sialic acid was accomplished. The results of a preliminary study on biological responses against influenza virus sialidases using thiosialoside clusters showed that some of the glycodendrimers have inhibitory potencies against the sialidases. [Copyright &y& Elsevier]

Abstract: A series of carbosilane dendrimers uniformly functionalized with sialyl lactose moieties (Neu5Acα2→3Galβ1→4Glc) was systematically synthesized, and biological evaluations for anti-influenza virus activity using the glycodendrimers were performed. The results suggested that the glycodendrimers had unique biological activities depending on the form of their core frame, and Dumbbell(1)6-amide type glycodendrimer 7 showed particularly strong inhibitory activities against human influenza viruses [A/PR/8/34 (H1N1) and A/Aichi/2/68 (H3N2)]. The results suggested that the structure–activity relationship (SAR) on the glycolibrary against various influenza viruses was observed, and dumbbell-shaped dendrimers as supporting carbohydrate moieties were found to be the most suitable core scaffolds in this study. [Copyright &y& Elsevier]

Abstract: An efficient synthesis of a series of carbosilane dendrimers uniformly functionalized with sialyl α(2→3) lactose (Neu5Acα(2→3)Galβ(1→4)Glcβ1→) moieties was accomplished. The results of a preliminary study on biological responses against influenza virus hemagglutinin, using the sialyl lactose clusters showed unique biological activities on the basis of the structure–activity relationship according to the carbosilane scaffolds. [Copyright &y& Elsevier]

Abstract: Carbosilane dendrimers periphery-functionalized with lactotriaose (GlcNAcβ1–3Galβ1–4Glc) with valencies of three, four, six, and twelve were prepared for use in a lectin-binding assay. A lactotriaose derivative was prepared from d-glucosamine and d-lactose derivatives. The N-Troc-protected glucosamine glycosyl donor and 3′-O-unprotected lactose glycosyl acceptor were condensed in the presence of silver trifluoromethanesulfonate and methylsulfenyl bromide to provide corresponding trisaccharide with new β-1-3 linkages in 92% yield. The protection group of the trisaccharide was transformed into an acetyl group. The 4-pentenyl glycoside was prepared from the acetate via glycosyl bromide. The alkene was converted into acetyl sulfide by addition of thioacetic acid under radical conditions. The lactotriaose unit was linked with carbosilane dendrimers to afford acetyl-protected glycodendrimers. De-O-acetylation of the dendrimers was carried out in the presence of sodium methoxide and then aq NaOH to give the desired lactotriaose clusters using a carbosilane dendrimer backbone. Their biological activities toward WGA were evaluated by fluorescence methods. The binding constants of free lactotriaose and trivalent, tetravalent, hexavalent, and dodecavalent glycodendrimers to WGA were determined to be 1.1×103, 4.4×104, 5.1×104, 2.8×106, and 1.3×106 M−1, respectively. The hexavalent glycodendrimer showed a 2500-fold larger binding effect than that of free lactotriaose. [Copyright &y& Elsevier]

Abstract: 4-Pentenyl (2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-(1→4)-(3,6-di-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl)-(1→3)-(2,6-di-O-benzoyl-β-d-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzoyl-β-d-glucopyranoside (4) was synthesized by regioselective glycosylation of 4-pentenyl (2,6,-di-O-benzoyl-β-d-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzoyl-β-d-glucopyranoside and (2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-(1→4)-3,6-di-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl chloride. By conversion of the protecting groups followed by thioacetylation, 4 was transformed into the corresponding lacto-N-neotetraose derivative, 5-(acetylthio)pentenyl (2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-(1→4)-O-(3,6-di-O-acetyl-2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→3)-(2,4,6-di-O-acetyl-β-d-galactopyranosyl)-(1→4)-2,3,6-tri-O-acetyl-β-d-glucopyranoside (6). The lacto-N-neotetraose derivative 6 was introduced into carbosilane dendrimer cores of three shapes, and three kinds of new carbosilane dendrimers peripherally functionalized by lacto-N-neotetraose were obtained. [Copyright &y& Elsevier]

Abstract: A new compound having a 2,3,4,5-tetraphenylsilole derivative on the center silicon of Dumbbell(1)6Gb3; Silole-Dumbbell(1)6Gb3 (1) was previously reported. It was found that 1 exhibited strongly increased fluorescence both in water and in a 96% acetone/water mixed solvent. The physical behavior of 1 in water and in the 96% acetone/water mixed solvent was investigated, and analyses including fluorescence quantum yields, dynamic-light-scattering (DLS), atomic-force-microscopy (AFM), and fluorescence microscopy were carried out. It was clarified that 1 dynamically formed different types of aggregates in water and in higher acetone concentrations to yield high aggregation-induced emission (AIE) effects due to the formation of micelle-like particles in water and inversion-type micelles in the acetone/water mixed solvent, respectively. [Copyright &y& Elsevier]

Abstract: A glycocluster peripherally functionalized with a lactose (Lac: Galβ1→4Glcβ1–) derivative possessing a silole moiety as a luminophore was synthesized. The photoluminescence spectrum of the glycocluster showed extremely strong emission at 474nm and the absolute quantum yield was estimated to be 92% in distilled water. The emission intensity was decreased by increasing the amount of peanut agglutinin (PNA), a lactose-binding lectin, and plots of the relative fluorescence intensity revealed a decline of 95% in emission intensity. Fluorescence quenching of the glycocluster upon mixing with PNA could be easily observed by the naked eye under UV irradiation, whereas no distinct change in fluorescence properties of the glycocluster was observed when wheat germ agglutinin (WGA) was employed. [Copyright &y& Elsevier]