Characterization and purification of glycosaminoglycans from crude biological samples

Chondroitin sulfate (CS) is a glycosaminoglycan derived from cartilage and commonly used to treat osteoarthritis, psoriasis, and other conditions. The dimethylmethylene blue (DMMB) assay has been used often to measure glycosaminoglycan levels in relatively pure samples. In this study, we verified the accuracy of the DMMB assay in measuring CS levels in unpurified extract from bovine trachea and shark cartilage, despite potential interference from salts, proteins, and DNA. We found that the glycosaminoglycan signal obtained was due to CS and not to other glycosaminoglycan species. This was confirmed using fluorophore-assisted carbohydrate electrophoresis, which also revealed that the majority of the CS was monosulfated at the C4 or C6 position. Finally, we used anion-exchange chromatography to purify the bovine extract and obtained complete recovery of the glycosaminoglycans, with no contaminating protein. The results of this study should be very useful for future purification and analysis of this common supplement.