Preparation of an α-cyclodextrin–linked chitosan derivative via reductive amination strategy
✍ Scribed by Tomoya Tojima; Hironori Katsura; Sang-Mun Han; Fusao Tanida; Norio Nishi; Seiichi Tokura; Nobuo Sakairi
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 133 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0887-624X
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✦ Synopsis
Introduction
acetylated chitin with an average molecular weight 60,000, with 50% (wt/v) aqueous NaOH for 2 h at 120ЊC Chitosan, 2-amino-2-deoxy-b(1,4)-glucan, is a polycatthree times. 7 ionic biopolymer prepared by de-N-acetylation of natu-Mono 2-O-allyl-a-cyclodextrin 2 was prepared by seral mucopolysaccharide chitin and has been regarded lective allylation of a-CD 1 with 3-bromopropene and as a multifunctional polymer applicable to various purlithium hydride-lithium iodide in dimethylsulfoxide pose such as an antifungal substance, 1 metal-ion ad-(DMSO) and purified by chromatography on a column sorbant, 2 and ion exchanger. 3 Studies on chemical modof Diaion HP-20 (Mitsubishi Chemical Co. Ltd.) using ification of chitosan have been extensively performed 20% (v/v) aqueous methanol. Compound 2 was treated to introduce novel functions into this biopolymer. 4 Rewith ozone in 50% aqueous methanol at 0ЊC for 4 h and cently, we have succeeded in synthesis of a chitosan then treated with dimethyl sulfide at room temperature derivative that possess an ability to form host-guest overnight, giving gave 2-O-(formylmethyl)-a-cyclodexcomplexes with a fluorescent dye. 5 This preparation intrin 3, which was used after concentration. Reactions volved condensation of chitosan with average molecular were monitored by TLC on a precoated silica gel 60 weight of 7300 and carboxymethylated b-cyclodextrin. 5 F 254 (layer thickness, 0.25 mm; E. Merck, Darmstadt, However, application to chitosan with higher molecular Germany) using n-BuOH-EtOH-H 2 O (6 : 4 : 3, v/v/ weight failed due to its extreme low solubility in water v) as the eluent. under the neutral or alkaline conditions that are necessary for the condensation reaction. During these investigations, we focused on Hanessian's report 6 concerning the preparation of a-cyclodextrin ( a-CD) derivatives by reductive amination of a-CD derivative with aldehyde function. This report promoted us to examine a novel Preparation of a-CD-Chitosan 5 method for the introduction of a-CD residue, which has the smallest hydrophobic cavity among the CD family, into chitosan with a high molecular weight. In this com-To a solution of chitosan (100 mg) in 0.2 M acetate munication, we preliminarily report the results thus obtained.
buffer at pH 4.4 (100 mL) was added a solution (50 mL) of 3 that was prepared form 2 (500 mg) was added by portions. The mixture was stirred for 1 h at room EXPERIMENTAL temperature, and sodium cyanoborohydride (260 mg) was added to the resulting solution. The mixture was Chitosan was prepared by treatment of Flonac C (Kystirred for 4 days at room temperature, neutralized owa Technos Co. Ltd., Chiba, Japan), partially de-Nwith 5% aqueous ammonia, subjected to dialyzation through a membrane with molecular cutoff of 10,000,