Alginate esters via chemoselective carboxyl group modification.
Alginates are (1→4) linked linear copolysaccharides composed of β-D-mannuronic acid (M) and its C-5 epimer, α-L-guluronic acid (G). Several strategies for synthesis of carboxyl modified alginate derivatives exist in the literature. Most of these however employ aqueous chemistries, such as carbodiimide coupling reactions. Based on our recently discovered method for homogeneous dissolution of tetrabutylammonium (TBA)-alginate, we now describe use of tetrabutylammonium fluoride (TBAF)-based two component solvent systems as media for synthesis of carboxyl-modified alginate esters. Partially and fully esterified benzyl, butyl, ethyl, and methyl alginates were synthesized via reaction with the corresponding alkyl halides. The newly synthesized derivatives were soluble in polar aprotic solvents without the addition of TBAF. Saponification was performed to demonstrate that alkylation was completely regioselective for carboxylate groups in preference to hydroxyl groups to form esters. We demonstrate the utility of these alginate esters to enhance aqueous solubility of the flavonoid naringenin by formation of solid dispersions.
Macromolecules and Interfaces Institute, Department of Sustainable Biomaterials, Institute for Critical Technology and Applied Science, Virginia Tech, Blacksburg, VA 24061, United States.
Siddhesh N
SN
Pawar
Kevin J
KJ
Edgar
D000464:Alginates / Q000737:chemistry*; D001672:Biocompatible Materials; D004952:Esters; D044950:Flavanones / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012503:Saponins / Q000737:chemistry; D012995:Solubility; D014867:Water
D000464:Alginates; D001672:Biocompatible Materials; D004952:Esters; D044950:Flavanones; D006603:Hexuronic Acids; D000644:Quaternary Ammonium Compounds; D012503:Saponins; D014867:Water; C007896:guluronic acid; D020723:Glucuronic Acid; C008324:mannuronic acid; C009405:tetrabutylammonium; C005273:naringenin; D005459:Fluorides
Alginate; Chemoselective; DS; Derivatization; Drug delivery; Enhancement; Esters; Modification; Naringenin; Solubility