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Semi‐Synthesis of Unusual Chondroitin Sulfate Polysaccharides Containing GlcA(3‐ O ‐sulfate) or GlcA(2,3‐di‐ O ‐sulfate) Units
Author(s) -
Bedini Emiliano,
De Castro Cristina,
De Rosa Mario,
Di Nola Annalida,
Restaino Odile F.,
Schiraldi Chiara,
Parrilli Michelangelo
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201102458
Subject(s) - polysaccharide , chemistry , chondroitin sulfate , glucuronic acid , sulfation , chondroitin , sulfate , monosaccharide , disaccharide , organic chemistry , stereochemistry , biochemistry , glycosaminoglycan
The extraction from natural sources of Chondroitin sulfate (CS), a polysaccharide used for management of osteoarthritis, leads to very complex mixtures. The synthesis of CS by chemical modification of other polysaccharides has seldom been reported due to the intrinsic complexity that arises from fine chemical modifications of the polysaccharide structure. In view of the growing interest in expanding the application of CS to pharmacological fields other than osteoarthritis treatment, we launched a program to find new sources of known or even unprecedented CS polysaccharides. As part of this program, we report herein on an investigation of the use of a cyclic orthoester group to selectively protect the 4,6‐diol of N ‐acetyl‐galactosamine residues in chondroitin (obtained from a microbial source), thereby facilitating its transformation into CSs. In particular, three CS polysaccharides were obtained and demonstrated to possess rare or hitherto unprecedented sulfation patterns by 2D NMR spectroscopy characterization. Two of them contained disaccharide subunits characterized by glucuronic acid residues selectively sulfated at position 3 (GlcA(3S)), the biological functions of which are known but have yet to be fully investigated. This first semi‐synthetic access to GlcA(3S)‐containing CS could greatly expedite such studies, since it can easily furnish considerable amounts of these polysaccharides, which are usually isolated with difficulty and in very low quantity from natural sources.