CARBOXYMETHYLATION OF GUAR GUM: SYNTHESIS AND CHARACTERIZATION

Recent studies focus on the chemical modification of polysaccharides for biomedical applications. Guar gum is a natural polymer composed of linear chains of (1-4)-β-D mannopyranosyl units with α-Dgalactopyranosyl units attached by (1-6) linkages, in a ratio of about 1.5-2, possessing hydroxyl groups available for the attachment of biologically active compounds. The modifications here discussed include the introduction of carboxymethyl groups into the molecule, for extending the applications of partially carboxymethylated guar gum. The carboxymethylation conditions with respect to the volume and concentration of sodium hydroxide, weight of chloro-acetic acid and reaction temperature were optimized. The resulting products were characterized by NMR and FTIR spectroscopy and by thermal gravimetric analysis (TGA). The carboxymethylated guar gum may provide an efficient alternative approach for the oral delivery of hydrophilic macromolecules.