Polysaccharide containing carboxyl group

Solubility is a very important criterium for the different uses of polysaccharides in pharmacy. Table 4 lists the solubility criteria of some polysaccharides in water. Solutions containing sugars and alcohol generally depress the solubility of polysaccharides. Polysaccharides containing carboxyl groups, i.e., pectins, alginates, and carboxy-methylcellulose, are insoluble at low pH values. They will be precipitated when the pH is lowered below 3. 

Polysaccharides containing carboxyl groups, such as chondroitin sulfate and hyaluronic acid, are derivatized with cysteine methyl ester by substituting carboxyl groups of polysaccharides and subsequently cross-linked by mild oxidation to form hydrogels. IPNs and semi-lPNs can also be degraded from backbone. 

Figure 1.29 Monosaccharides containing carboxylate groups. Sialic acid often is found at the terminal residues of polysaccharides within glycoproteins.

Also other polysaccharides containing carboxyl and amino groups such as chondroitin sulphate, dermatan sulphate N-carboxymethyl diitosan, and some bacteria polysaccharides may be used in a similar manner to build up ultrathin coatings on smfaces with defined attachments and mean thickness. 

In several polysaccharides containing glycuronic acid residues, the carboxyl groups of these are linked to the amino group of amino compounds, forming amides. In the simplest examples, these are primary amides, such as the 2-formamido- and 2-acetamido-2-deoxy-D-galacturonamide (49) residues in 0-specific polysaccharides from different strains of Pseudomonas... 

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