- Synthesis of branched cyclodextrins using activated carbon as a catalyst
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Activated carbon has been reported to act as a catalyst for condensation reactions between glucose molecules. The present study describes the use of activated carbon as a new catalyst for the synthesis of branched cyclodextrins (CDs). Two main methods have been used to synthesize branched CDs: a method using an enzymatic condensation or transfer reaction, and a method using a chemical reaction. However, these methods have problems such as a limited number of the types of branched CDs that can be synthesized that depend on the characteristics of the enzyme, the long reaction time required (several days or more), difficulty in synthesizing branched CD with a high degree of substitution (DS), the need for large quantities of environmentally harmful solvents, and a complicated and costly reaction. Using activated carbon as a catalyst, branched CDs with a high DS could be synthesized within a relatively short time (a few hours), regardless of the type of saccharide in the branched portion. Furthermore, since the reaction was conducted under solvent-free conditions using activated carbon, the amount of solvent used in the production of branched CD could be reduced. The branched β-CDs prepared using the activated carbon catalyst showed high solubility, high solubilization capacity, and low hemolytic activity, similar to the 2-hydroxypropyl-β-CD used for pharmaceuticals. These results indicate that activated carbon is an industrially and environmentally useful catalyst for branched CD syntheses.
- Ishikura, Kandai,Yanagihara, Kazunori,Takagi, Hiroki
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- ENZYMIC SYNTHESES OF DOUBLY BRANCHED CYCLOMALTOHEPTAOSES THROUGH THE REVERSE ACTION OF Pseudomonas ISOAMYLASE
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Two and three new cyclomaltoheptaose (β-cyclodextrin, cG7) derivatives, respectively, were identified among the products obtained by the action of Pseudomonas isoamylase on maltose and maltotriose, and cG7.They were 6A,6D-di-O-α-maltosyl-cG7 and 6-O-α-(62-O-α-maltosyl)maltosyl-cG7, and 6A,6D-di-O-α-maltotriosyl-cG7, 6-O-α-(63-O-α-maltotriosyl)maltotriosyl-cG7, and 6-O-α-(62-O-α-maltotriosyl)maltotriosyl-cG7.In addition, 61- and 62-O-α-maltosylmaltose were identified as mutual condensation products of maltose.Maltose was the smallest substrate to act as both an acceptor and a donor for the action of Pseudomonas isoamylase.
- Abe, Jun-ichi,Hizukuri, Susumu,Koizumi, Kyoko,Kubota, Yoko,Utamura, Toshiko
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- SYNTHESIS OF 6-O-α-D-GLUCOPYRANOSYLCYCLOMALTOHEPTAOSE
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(2,3-Di-O-acetyl)hexakis(2,3,6-tri-O-acetyl)cyclomaltoheptaose was prepared by reaction of cyclomaltoheptaose with tert-butyldimethylsilyl chloride in pyridine followed by acetylation and desilylation.Glycosylation with 2,3,4,6-tetra-O-benzoyl-1-O-trichloroacetimidoyl-α-D-glucopyranose, using trifluoromethanesulfonic acid as catalyst, and removal of the protecting groups from the product then afforded the title compound.
- Fuegedi, Peter,Nanasi, Pal,Szejtli, Jozsef
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p. 173 - 182
(2007/10/02)
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- ISOLATION AND CHARACTERIZATION OF BRANCHED CYCLODEXTRINS
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Three branched cyclodextrins (CDs) were isolated by high-performance liquid chromatography (l.c.) from the mother liquors of a large-scale preparation of the unbranched CDs with Bacillus ohbensis cyclomaltodextrin glucanotransferase.Evidence from chromatographic behavior on three l.c. coloumns of different separation modes, fragmentation analysis, 13C-n.m.r. spectroscopy, methylation analysis, and fast-atom bombardment-mass spectroscopy (f.a.b.-m.s.) indicated that these compounds were 6-O-α-D-glucopyranosylcyclomaltohexaose (1), 6-O-α-D-glucopyranosylcyclomaltoheptaose (2), and 6,6'''-di-O-α-D-glucopyranosylcyclomaltoheptaose (3).
- Koizumi, Kyoko,Utamura, Toshiko,Sato, Michikatsu,Yagi, Yoshiaki
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- Synthesis of branched cyclomalto-oligosaccharides using Pseudomonas isoamylase.
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Branched cyclomalto-oligosaccharides (cyclodextrins) were synthesised from cyclomalto-oligosaccharides and maltose or maltotriose through the reverse action of Pseudomonas isoamylase. The reaction rate was greater with maltotriose than with maltose, and with increasing size of the cyclomalto-oligosaccharide (cG6 less than cG7 less than cG8). Maltotriose is effective as both a side-chain donor and acceptor, and three isomers of 6-O-alpha-maltotriosylmaltotriose (branched G6) were formed through mutual condensation, but maltose was effective only as a side-chain donor. Each branched cyclomalto-oligosaccharide and G6 was purified by liquid chromatography, and their structures were determined by chemical, enzymic, and 13C-n.m.r. spectroscopic analyses.
- Abe,Mizowaki,Hizukuri,Koizumi,Utamura
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