Chitosan acetylation

Fig. 6. Effect of the degree of chitin acetylation (%) on the interaction between chitin and chitin-specific wheat POs (A) (U/ mg protein) (Maksimov et al., 2005) (B) PAAG after lEF of PO fractions from wheat roots (a) not bound to high-acetylated (b) and low-acetylated chitosan (c) (Khairullin et al., 2000). Designations (1) 12% (2) 23% (3) 37% (4) 45% (5) 65%.

We initially prepared the first chitosan-sialoside hybrid 19 by treating 80% de-AT-acetylated chitosan with p-formylphenyl a-sialoside 6 (Scheme 1) under reductive amination conditions (NaBH3CN) (Scheme 7) [64]. The level of sialo-side incorporation could be controlled by increasing the amount of 6 (Table 15.2). The reactivity of aldehyde 6 toward chitosan was found to be in the range 25-48% due to excessive reduction of the aldehyde under the acidic reaction conditions. Water-soluble materials were only achieved at high DS (DS > 0.53). Sialo-hybrids with lower substitutions were further derivatized with succinic... 

Chitin and chitosan derivatives have also been studied as blood compatible materials both in vivo and in vitro [520], Anticoagulant activity was greatest with O sulfated N acetyl chitosan, followed by N,0 sulfated chitosan, heparin, and finally sulfated N acetyl chitosan. The lipolytic activity was greatest for N,0 sulfated chitosan followed by heparin. The generally poor performance of chitosan was attributed to polyelectrolyte complexes with free amino groups present on the membrane surface. The O sulfate or acidic group at the 6 position in the hexosamine moiety was identified as the main active site for anticoagulant activity. 

Aiba, S. (1989). Studies on chitosan 2. Solution stability and reactivity of partially N-acetylated chitosan derivatives in aqueous media. Int. ]. Biol. Macromol. 11, 249-252. 

Aiba S-i (1991) Studies on chitosan 3. Evidence for the presence of random and block copolymer structures in partially N-acetylated chitosans. Int J Biol Macromol 13(l) 40-44... 

Kato, Y., Kaminaga, J., Matsuo, R., and Isogai, A., TEMPO-mediated oxidation of chitin, regenerated chitin and N-acetylated chitosan. Carbohydrate Polymers 2004, 58 (4), 421-426. 

V-acetylated chitosan membrane Sulzer Pervap-2255 membrane Cuprophane membranes... 

Huang RYM, Moon GY, and Pal R. N-acetylated chitosan membranes for the pervaporation separation of alcohol/toluene mixtures. J. Memb. Sci. 2000 176(2) 223-231. 

Varum KM, Myhr MM et al (1997) In vitro degradation rates of partially N-acetylated chitosans in human serum. Carbohydr Res 299 99-101... 

The A. coerulea material was poorly crystalline, showing a broad peak at 20° 20, but the spectrum for the alkali-treated material showed a broad peak at 10.72° and two peaks at 18.72° and 19.98° 20, with close similarity to the spectrum of authentic chitosan. Optical microscopy showed that the alkali-treated products, stained with Saphranine or with other stains, preserved the morphology of the fungus, with flattened and empty structures [30] (Fig. 1). This work introduced the concept that an extended surface area of the carbohydrate polymer leads to enhanced performance, as amply confirmed by most recent works dealing with chitin and chitosan nanofibrils. In fact, the partially re-acetylated chitosan (degree of acetylation 0.23) is promptly depolymerized by lysozyme, papain, and lipase thanks to the ideal degree of acetylation for maximum enzymatic activity. Remarkably, the re-acetylated... 

Kubota, N., Tatsumoto, N., Sano, T., and Toya, K. A simple preparation of half N-acetylated chitosan highly soluble in water and aqueous organic solvents. Carbohydr. Res. 324 (2000) 268-274. 

Lamarque, G. Lucas, J.-M. Viton, C. Domard, A. Physicochemical behavior of homogeneous series of acetylated chitosans in aqueous solution Role of various structural parameters. Biomacromolecules... 

In order to modify or enhance specific properties of chitosan, chemical derivatives have been synthesized by using the amines and hydroxyl groups in the molecular structure. Some examples include trimethyl chitosan, glycol chitosan, carboxymethyl chitosan, half-acetylated chitosan, and thiolated chitosan." ... 

Separation of alcohol toluene mixture. V-Acetylated chitosan membrane Additional acetyl groups in the membrane decreased the flux but increased a. [195]... 

Figure 4.1 Repeat unit of (a) chitin (polyf N-acetyl-p-D-glucosamine)), and (b) chitosan (poly(D-glucosamine). (c) Structure of partially acetylated chitosan characterized by an average degree of acetylation DA.

Kubota, N. and Eguchi, Y. (1997) Facile preparation of water-soluble N-acetylated chitosan and molecular weight dependence of its water-solubility. Polymer Journal, 29, 123-127. 

Huang, R.Y.M., Moon, G.Y. and Pal, R. 2000. N-Acetylated chitosan membranes for the pervaporation separation of alcohols/toluene mixtures, 176 223-231. 

Aiba, S. 1994. Preparation oflV-acetylchitooligosaccharides by lysozymic hydrolysates of partially M-acetylated chitosans. Carbohydr. Res. 261 297-306. 

Varum, K.M., Holme, H.K., Izume, M., Stokke, B.T., and Smidsrod, O. 1996. Determination of enzymatic hydrolysis specificity of partially A-acetylated chitosans. Biochem. Biophys. Acta 1291 5-15. 

The principle of functional group modification is to alter existing physical and chemical properties of chitosan in order to promote its capacity to deliver pDNA. Examples of vectors derived by functional group modification include thiolated chitosan (CSH) and A-acetylated chitosan. 

A-acetylated chitosan is another example of a functional-group-modification-derived chitosan-based pDNA carrier. Kai and Ochiya (2004) have previously reported its potential application in oral gene delivery. In their study, mice were fed with A-acetylated polyplexes carrying pDNA encoding lacZ and interluekin-10. The result of lacZ staining performed 5 days after transfection showed that transgene expression in duodenum, jejunum, ileum, and colon could only be mediated by A-acetylated chitosan but not standard chitosan. However, no evaluation on the toxicity of this chitosan derivative has yet been published. In order to further verify its workability in clinical use, studies on its toxicology and safety are in dire need. 

Aiba, S. 1992. Studies on chitosan 4. Lysozymic hydrolysis of partially A-acetylated chitosans. International Journal of Biological Macromolecules 14 225-228. 

Kai, E. and Ochiya, T. 2004. A method for oral DNA delivery with N-acetylated chitosan. Pharmaceutical Research 21 838-843. 

Ogawa, K. and T. Yni. 1993. Crystallinity of partially A-acetylated chitosans. Bioscience, Biotechnology and Biochemistry 57(9) 1466-1469. 

Mitsutomi, M., M. Ueda, M. Arai, A. Ando, and T. Watanabe. 1996. Action patterns of microbial chitinases and chitosanases on partially V-acetylated chitosan. In Chitin Enzymology, Vol. 2, ed. R. A. A. Muzzarelli, pp. 272-284. Grottamare, Italy Atec. 

Vlirum, K. M., B. Egelandsdal, and M. R. EUekjaer. 1995. Characterization of partially V-acetylated chitosans by near infrared spectroscopy. Carbohydr. Polym. 28 187-193. 

Martinou, A., Bouriotis, V., Stokke, B. T., and Varum, K. M. 1998. Mode of action of chitin deacetylase from Mucor mwcii on partially V-acetylated chitosans. Carbohydr Res 311 71-78. 

Nordtveit, R.J., Varum, K. M., andSmidsrod, 0.1994. Degradation of fully water soluble partially Af-acetylated chitosan with lysozyme. Carbohydrate Polymers, 23 253. 

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