Stability studies of chondroitin sulfate

The stability of chondroitin sulfate (CS) was studied under acidic, neutral and basic conditions at 30 and 60 °C. CS is remarkably stable under neutral conditions at low temperature, while it degrades at 60 °C producing low-molecular-mass fragments and desulfated products. This decomposition process begins at ca. 500–600 h and is consistent with an acid-catalyzed hydrolysis of glycosidic linkages caused by a drop in pH resulting from acidic products. Under basic conditions, a breakdown of glycosidic linkages causes a decrease in molecular mass due to the β-elimination reaction, confirmed by a strong increase of absorbance at 232 nm and 1H NMR. Virtually no loss of O-sulfate groups can be detected in the base-treated CS. Under acidic conditions, the molecular mass decreases probably through hydrolysis of polysaccharidic linkages resulting in an increased number of reducing end groups. Little or no β-elimination occurs. A loss of O-sulfate groups was detected, producing desulfated derivatives.