Synthesis, characterization, and preliminary biological study of glycoconjugates of poly(styrene-co-maleic acid)

Three derivatives of the biocompatible polymer poly(styrene-co-maleic anhydride) (SMA) were obtained with 1-amino-1-deoxy-beta-D-galactose, 1-amino-1-deoxy-beta-D-glucose, and 1-amino-1-deoxy-beta-D-lactose, respectively. The amino sugars were chemically conjugated via formation of an amide bond between the anomeric amino group of the sugar residue and the anhydride of the copolymer, giving the corresponding glycoconjugate derivatives. Colorimetric assay of the unreacted amino groups and elemental analysis were used to determine the degree of substitution. About 56%, 54%, and 94% of the available anhydride groups reacted to give galactosyl-amide (SMA-Gal), glucosyl-amide (SMA-Gluc), and lactosyl-amide (SMA-Lac) branched polymers, respectively. The synthesized glycopolymers were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, circular dichroism, and UV and fluorescence spectroscopy. The release of glucosylamine from the glucosyl-amide branched polymer, by basic hydrolysis, was monitored by high-performance anion-exchange chromatography and by capillary electrophoresis, providing for an additional check of the degree of substitution of this specific polymer derivative. Biological activity tests showed that both SMA-Gal and SMA-Lac allow adhesion of HepG2 hepatic cells about five times larger than that of hydrolyzed, underivatized SMA.