Inulin polysaccharide having pendant amino acids: Synthesis and characterization

Inulin polysaccharide was esterified with N-protected α-amino acids (N,N′-di-benzylocarbonyl-L -lysine and N-benzylocarbonyl-glycine) under a mild condition (room temperature) and within short reaction times (6 h). The esterification reactions were conducted in the presence of dicyclohexylcarbodiimide and 4-(dimethylamino)pyridine as a catalyst. The optimal reaction time (6 h) was determined by monitoring the concentration of free carboxylic acid of the N-protected amino acids during the reaction. The degree of substitution per fructose unit was 0.95 for inulin-lysine and 1.01 for inulin-glycine. The resulting biopolymer was deprotected by catalytic transfer hydrogenation method using 1,4-cyclohexadiene as an effective hydrogen donor. The structures, molecular weight, and thermal properties of the amino acid esters of inulin were determined by Fourier transform infrared spectroscopy, ¹H and ¹³C NMR, UV, viscosity, and dicyclohexylcarbodiimide. This new modified inulin polysaccharide would have the potential as a biomaterial for biomedical applications. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 953–963, 1998