Synthesis of amphiphilic 6-carboxypullulan ethers

• Published in: Carbohydrate polymers Vol. 100; no. 1; pp. 65 - 73
• Main Authors: Pereira, Junia M., Mahoney, Michelle, Edgar, Kevin J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 16.01.2014; Elsevier
• Subjects: 6-Carboxypullulan; Amphiphilic; Applied sciences; Chemistry Techniques, Synthetic; Cyclic N-Oxides - chemistry; Drug delivery; Etherification; Ethers - chemistry; Exact sciences and technology; Glucans - chemical synthesis; Glucans - chemistry; Hydrophobic and Hydrophilic Interactions; Natural polymers; Oxidation; Oxidation-Reduction; Physicochemistry of polymers; Regioselective synthesis; Solubility; Starch and polysaccharides; Surfactant; Amphiphilic; Oxidation; Drug delivery; Regioselective synthesis; Surfactant; 6-Carboxypullulan; Etherification; Experimental study; Piperidone derivatives; Lateral group; Polyelectrolyte; Chemical modification; Micellar critical concentration; Halogenated hydrocarbon; Preparation; Hypochlorites; Hydrophobic group; Oside polymer; Polyacid; Aqueous solution; Amphiphilic polymer
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2012.12.029

► 6-Carboxypullulan, in its TBA salt form, is soluble in a range of organic solvents. ► Etherification of 6-carboxypullulan TBA salt was performed homogeneously in DMSO. ► A range of 6-carboxypullulan ethers with DS ranging from 3 to 7 was synthesized. ► DS depends on conditions and the type of alkyl halide reacted with 6-carboxypullulan. Hydrophobically modified polysaccharides that contain carboxyl groups possess exceptional features for drug delivery and other applications. Carboxyl groups were introduced at C-6 in the pullulan backbone by applying the well-established oxidation with TEMPO and NaOCl/NaBr. The oxidized product, 6-carboxypullulan, is even more water-soluble than pullulan. Consequently, further chemical modifications have been mainly restricted to reactions that can be performed in water or under heterogeneous conditions. We find that the TBA salt of 6-carboxypullulan is soluble in a range of organic solvents and can be reacted homogeneously with various alkyl halides in DMSO and sodium hydroxide at 40°C to yield 6-carboxypullulan ethers. Complete substitution (DS 7 per trisaccharide repeat unit) was achieved upon reaction with iodoethane, while products from reaction with longer chain alkyl halides (propyl and butyl derivatives) achieved DS up to about 3. The amphiphilic products have impressive surfactant properties.