1997 Fiscal Year Final Research Report Summary
Preparation and Properties of Nonnatural Branched Amino Polysaccharides
| Project/Area Number |
08651061
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
高分子合成
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| Research Institution | Seikei University |
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Principal Investigator |
KURITA Keisuke Seikei Univ.Ind.Chem.Dept.Prof., 工学部, 教授 (30102180)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIYAMA Yasuhiro Seikei Univ.Ind.Chem.Dept.Assoc.Prof., 工学部, 助教授 (30286900)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Chitin / Chitosan / Branched Polysaccharide / Glycosylation / Biodegradation / Chemical Modification / Protecting Groups / Antimicrobial Activity |
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| Research Abstract |
Nonnatural branched amino polysaccharides have been prepared through a series of regioselective modification reactions of chitosan and evaluated in terms of their solubility, biodegradability, and antimicrobial activity.
N-Phthaloyl-chitosan was used as an organosoluble precursor to prepare polysaccharide acceptors having reactive groups only at C-6. Glycosylation reaction of the acceptor having trimethylsilyloxy groups at C-6 with an orthoester of D-mannose in dichloromethane proceeded smoothly in the presence of trimethylsilyl trifluoromethanesulfonate.The degree of substitution was up to 0.6. The products were then deprotected to give chitosans having alpha-mannoside branches, and the subsequent N-acetylation afforded the corresponding chitin derivatives. The branched chitosans and chitins were efficiently aggregated by concanavalin A in aqueous solution owing to the presence of alpha-mannoside groups. Though nonnatural, the branched chitins were susceptible to lysozyme. The branched chitosans exhibited antimicrobial activity.
In a similar manner, beta-galactoside branches were introduced into chitosan and chitin, and both the products were highly hygroscopic. The galactoside-chitin was also degraded enzymatically.
Glycosylation with an oxazoline derivative of D-glucosamine was possible in dichloroethane with camphorsulfonic acid as the catalyst, and similar results were obtained from either acceptor having trimethylsilyloxy or hydroxy groups at C-6. The degree of substitution could be raised to 0.6 under appropriate conditions. Deprotection gave chitosans having beta-glucosaminide branches, and N-acetylation gave chitins having N-acetyl-beta-glucosaminide branches. They exhibited considerable antimicrobial activities.
All the branched chitosans and chitins prepared in this study were readily soluble in neutral water unlike insoluble chitosan and chitin. They would thus have high potentials as water-soluble advanced materials in various fields.
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