Acid glycosaminoglycans and their chemical modification

The modem state of chemical modification of hyaluronic acid, chondroitin sulfates, and heparin is considered, and the possible application of modified glycosaminoglycans as potential drugs is discussed.     

Modification of hyaluronic acid with aromatic amino acids

Hyaluronic acid was modified with aromatic amino acids (5-aminosalicylic, 4-aminosalicylic, anthranilic, and p-aminobenzoic) in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The modified glycans contained 9-43% of arylamide groups and 10-33% of isoureidocarbonyl groups depending on the nature of the amino acid. Reduction with sodium borohydride allowed the conversion of isoureidocarbonyl groups into hydroxymethyl groups.     

Chemical modification of heparin

Heparin was modified at carboxyl groups by reaction with several pharmacologically important amino-containing compounds in aqueous medium in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. In dependence on the nature of the amine and the ratio of reagents, conjugates containing 36-100% amide and 0-25% isoureidocarbonyl groups were synthesized. Isoureidoarylamide groups are present, along with amide moieties, in the products of heparin modification by hydroxyl-containing aromatic amines. The conjugate of heparin with p-aminobenzoic acid contained oligomeric arylamide.