Physicochemical, structural characterization, and antioxidant activities of chondroitin sulfate from Oreochromis niloticus bones

Abstract

In this study, chondroitin sulfate was extracted from Oreochromis niloticus bones (OCS) and isolated to three fractions (OCS-1, OCS-2, and OCS-3). The physicochemical properties and structure characterization including monosaccharide, disaccharide compositions, molecular weight (Mw) of OCS were determined by HPAEC, HPLC-SAX, HPGPC, FT-IR spectra, and 1D/2D NMR. Moreover, their thermal properties, crystalline structure, and microstructure were also analyzed. Results showed that their Mw were between 10 kDa and 50 kDa. CS-6 was the predominant disaccharide unit in four OCS, and the CS-4/CS-6 ratios were close to CS from shark cartilage. Besides, the results of antioxidant activity showed that different fractions of OCS had a distinct DPPH radical, hydroxyl radical, and ABTS+ radical scavenging activity. OCS-1 has the highest scavenging activities in DPPH and hydroxyl radical compared with other fractions, which showed a higher medicinal value. Those findings may lay some theoretical basis for the potential application development of OCS.