Carboxymethylated-chitin chitosan

In this report, focusing to carboxymethyl chitin/chitosan and carboxymethyl cellulose, we studied the reactivity of water radiolysis products with polymer chains using the pulse radiolysis method as the first step to clarify early gelation process of polymer radicals related to crosslinking. 

Figure 1. Structure of carboxymethyl chitin/chitosan (left)and carboxymethyl...

FU(1), chitosan-5FU(2), a-l,4-polygalactosamine-5FU(3), partially N-acetylated a-l,4-polygalactosamine-5FU(4), hyaluronic acid-5FU(5), dextran-5FU(6), and 6-0-carboxymethyl chitin(CM-chitin)-5FU(7). 

Carboxymethyl-chitin (CM-chitin), as a water-soluble anionic polymer, is the second most studied derivative of chitin after chitosan. The carbox-ymethylation of chitin is imdertaken in a similar manner to that of... 

Chitin, a waste material from crab and shrimp processing, is poly(N-acetyl-D-glucosamine). The de-acetylated form, chitosan, is primarily used in water purification but is also used as a chemical feedstock. For example, chitosan can be depolymerized to the monomer, which is used as a hair-setting agent in shampoo and hair conditioner. In the future, graft polymers of chitosan may form biodegradable films. Already, carboxymethylated chitin is approved as a food wrap. 

Sodium carboxymethyl chitin Chitin, deacylated. See Chitosan Chitin Liq. Chitisoi. See Carboxymethyl chitin Chitobiase Chitodextrinase. See Glucanase Chitogiycan . See Carboxymethyl chitosan Chitosamine. See Glucosamine Chitosan... 

Carboxymethyl chitosan L-Camitine Chitin Chitosan Chitosan lactate Chlorella ferment Citrulline Collagen ... 

Bakers yeast extract Baker s yeast glycan Calcium acetate Calcium alginate Calcium carboxymethyl cellulose Calcium carrageenan Calcium chloride Calcium furcelleran Calcium gluconate Calcium glycerophosphate Calcium lactate Calcium sulfate Calcium sulfate dihydrate Carboxymethylcellulose sodium Carrageenan (Chondrus crispus) Carrageenan (Chondrus crispus) extract Cassia gum Cellulose Chitin Chitosan Corn (Zea mays) starch Corn starch, waxy Corn syrup Dextrin Distarch phosphate Ethyl hydroxyethyl cellulose Ferrous sulfate anhydrous Food starch, modified ... 

Chitinase assay was determined by a modified Schales procedure using colloidal and/or soluble chitin as the amount of enzyme that liberated 1 pmol of reducing sngar per minute (Imoto and Yagishita 1971). This method was nsed as the standard assay. To measnre the activity toward other substrates, powdered chitin, colloidal chitin, carboxymethyl chitin, ethylene glycol chitin, chitosan 7B, chitosan 8B, chitosan 9B, chitosan lOB, p-nitrophenyl-P-o-A-acetyl glucosaminide (pNP-Gl-cNAc), and several chitin/chitosan oligomers were used instead of solnble chitin. 

Chemical. A large number of chitin and chitosan derivatives have been synthesized through modification of the primary (C-6) and secondary (C-3) hydroxyl groups present on each repeat imit, including amine (C-2) functionality existing on deacetylated imits (31). Reactions typical of hydroxyl and amine groups (such as acylations with acid chlorides and anhydrides) including urethane and urea formation respectively, are feasible with isocyanates. The primary amine can be quatemized by alkyl iodides or converted to an imine with a variety of aldehydes and ketones that can subsequently be reduced to an N-alkylated derivative. Chitin and chitosan are reactive with a variety of alkyl chlorides after treatment with concentrated NaOH. Important derivatives such as carboxymethylated chitin and chitosan are commonly produced in this manner with the addition of sodium chloroacetate. 

In order to develop an efficient drug delivery carrier it is important for it to possess the following qualities. It should be immediately and completely removed after delivering drugs, it should not be accumulative or toxic in nature. Recent studies have proved the applicability of some chitin derivatives such as carboxymethyl chitin (CMC), chitosan hydrogel, and hydroxy-ethyl chitin have been shown to possess such characteristics (Ishihara et al., 2006 Dev et al., 2010). 

Muzzarelli RAA (1988) Carboxymethylated chitins and chitosans. Carbohyd Poiym 8 1-21... 

Muzzarelli, R. A. A. Carboxymethylated chitin and chitosan. Carbohydrate Polymers... 

Recent progress of basic and application studies in chitin chemistry was reviewed by Kurita (2001) with emphasis on the controlled modification reactions for the preparation of chitin derivatives. The reactions discussed include hydrolysis of main chain, deacetylation, acylation, M-phthaloylation, tosylation, alkylation, Schiff base formation, reductive alkylation, 0-carboxymethylation, N-carboxyalkylation, silylation, and graft copolymerization. For conducting modification reactions in a facile and controlled manner, some soluble chitin derivatives are convenient. Among soluble precursors, N-phthaloyl chitosan is particularly useful and made possible a series of regioselective and quantitative substitutions that was otherwise difficult. One of the important achievements based on this organosoluble precursor is the synthesis of nonnatural branched polysaccharides that have sugar branches at a specific site of the linear chitin or chitosan backbone [89]. 

Numerous substituted derivatives of chitin and chitosan are known [67] some important examples are shown in Scheme 10.9. The possibility of forming either anionic (5,7,8,11) or cationic (9,12) derivatives should be noted. The O-carboxymethyl (5) and N-carboxymethyl (11) polymers are of particular interest as they have stronger complex-forming capabilities with metal ions than either unsubstituted chitosan or EDTA [65]. In practice, derivatives formed by substitution via the 2-amino group of chitosan are more common than those substituted via the 6-hydroxy position of the glucopyranose grouping [65]. 

A comparative study of chitin obtained from lobsters, starch, and carboxymethyl chitosan as disintegrating agents was conducted. The influence of the method in the preparation of tablets on the disintegrating activity of both polymers was evaluated. Chitin proved to have good characteristics as a disintegrating agent independently... 

Figure 3 is the result of pulse radiolysis experiment about the reaction of hydrated electron with polymer chains(0 or 30 mM carboxymethyl chitosan solution with 0.3 M terf-butanol under Ar saturation), and shows the decay of the absorbance as a function of time. This absorbance was measured at wavelength 720 nm, which is the absorption peak of hydrated electron. As seen in Figure 3, the absorbance increases immediately after the irradiation, and attenuates afterwards. This means that hydrated electron is generated immediately after irradiation and diminishes gradually by some reactions of hydrated electron. Compared the absorbance decay of polymer solution with the decay of solution without polymer, the decay of polymer solution is faster than without polymer, so it is obvious that hydrated electron reacts with polymer chains. The decay curve can be fitted by pseudo first-order decay. The pseudo first-order decay is shown by equation (8). From estimating the slope of the pseudo first-order decay rate of the absorbance at 720 nm against polymer concentration, the rate constant of the reaction of hydrated electron with polymer chains can be calculated Figure 4). The rate constants of the reaction of hydrated electron with CM-chitin and CM-chitosan was determined as l.lxlO7 and MxlO M V1]. These values are almost the same with the value of carboxymethyl cellulose(2< ).

A complete list of semi-synthetic heparinoids is outside the scope of this article. Products of sulfation of neutral polysaccharides include sulfates of starch, cellulose, - - xylan, dextran, " guaran, and synthetic polymers of o-glucose. A somewhat closer simulation of the structure of heparin was attempted by sulfating polysaccharides containing amino sugars or uronic acids or both, such as chitin and chitosan, " and the corresponding N-formyl, N-(car-boxymethyl), O-(carboxymethyl), and 5-carboxylated - deriva-... 

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