Quantitative and Qualitative Evaluation of Chondroitin Sulfate in Dietary Supplements

We propose to evaluate the amount and quality of chondroitin sulfate (CS) from several food supplement preparations in the form of tablets, caplets, or capsules containing CS in varying contents and formulations in the presence of various additives and ingredients, with no other pretreatment than centrifugation to remove insoluble material. To quantify CS, two different analytical approaches were applied after their validation: specific and sensitive agarose-gel electrophoresis and strong-anion exchange-high-performance liquid chromatography (SAX-HPLC) determination of the constituent disaccharides after treatment with specific chondroitin lyases. The CS content in finished products evaluated using the two specific validated methods were found to conform to the label specifications. It is worth mentioning that the quantitative determinations have been performed using a very high pure European Pharmacopeia CS reference standard having substantially the same properties as the food supplement CS samples. Furthermore, by means of the specific agarose-gel elctrophoresis approach, we can exclude the presence in the nutraceuticals of other sulfated polysaccharides produced by extraction from tissues, in particular heparin, heparan sulfate, and dermatan sulfate. The SAX-HPLC separation of unsaturated disaccharides for the nutraceutical CS was also used to evaluate its quality and the possible origin. No disulfated disaccharides typical of CS from cartilaginous fishes, making the charge density lower than 1.0, were found, thus confirming the bovine or porcine origin, the most common sources of this "terrestrial" polysaccharide. Finally, high-performance size-exclusion chromatography (HPSEC) analysis was applied to evaluate the CS molecular mass in food supplements also in the presence of additives and other ingredients. This analytical approach confirmed that the nutraceutical CS samples are of high molecular mass and are not degraded during the food supplement preparations. In conclusion, this multianalytical approach can be used in the direct quantitation and evaluation of the quality and the possible origin of CS contained in food supplement formulations.