Characteristic oligosaccharides released from acid hydrolysis for the structural analysis of chondroitin sulfate.

Because the glycosidic linkage of uronic acid is most resistant to acid, oligosaccharides may be formed during the acid hydrolysis of acidic polysaccharides. To take chondroitin sulfate (CS) as an example of acidic polysaccharides, the present study characterized the oligosaccharides released through acid hydrolysis and demonstrated their usefulness for structural confirmation. Acid hydrolysates of commercial standard CSs from shark cartilage and porcine bone were elucidated using HPLC-MSn after 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatization, and altogether 11 di-, tri- and tetra-saccharides with or without sulfate/acetyl groups were identified by their multi-stage mass spectra. Meanwhile the trends of reaction yields of these oligosaccharides alone with trifluoroacetic acid (TFA) concentrations (0.1-2.0 M) were investigated, and 0.2 M TFA was recommended. Then three real samples, sturgeon backbone, porcine trachea and sea cucumber were analyzed, and their CSs were identified by detection of characteristic oligosaccharide fragments. The present study indicated that acid hydrolysis could provide information for acetyl substitution, sulfation and glycosidic linkages, and was helpful for the structural analysis of acidic polysaccharides.