Study On The Extraction, Isolation And Antioxidant Activity Of Chondroitin Sulfate From Sheep Cartilage

The numbers of breeding and slaughter of sheep in China are among the most in the world. As the byproducts of butchering and processing, sheep cartilage is a good source for producing chondroitin sulfate. In order to take full advantage of rich sheep cartilage resources and improve the value-added of sheep industry, chondroitin sulfate was extracted and separated from sheep cartilage by alkali extraction, enzymatic hydrolysis and ultrafiltration methods. Single factor experiment and quadratic regression orthogonal design were applied to optimize the technological conditions, and thus to improve the yield and purity of chondroitin sulfate. In addition, antioxidant activity of chondroitin sulfate has also been studied, to provide the theoretical basis for developing chondroitin sulfate with bioactivity. The main results are as follows:On the base of the single factor experiment of alkali extraction technique on chondroitin sulfate from sheep cartilage, the method of quadratic regression orthogonal design was carried out and the influence factors of the technological parameters were determined by means of regression analysis. The results showed that the optimum conditions were as follows:ratio of material to solvent 1:6.5, extraction time 2 h, extraction temperature 35℃, and alkaline concentration 7%. Under this condition, the yield of chondroitin sulfate from sheep cartilage was 12.65%.On the base of the single factor experiment of enzymatic extraction technique on chondroitin sulfate from sheep cartilage, the method of quadratic regression orthogonal design was carried out and the influence factors of the technological parameters were determined by means of regression analysis. The results showed that the optimum conditions were as follows:ratio of material to solvent 0.9:1000, pH 8.3, extraction temperature 47℃, extraction time 170 min. Under this condition, the yield of chondroitin sulfate from sheep cartilage was 15.87%. Chondroitin sulfate was purified by ultrafiltration. The results showed that the optimum conditions of ultrafiltration were:pressure 0.18 MPa, temperature 20℃, under which condition the purity and the yield of chondroitin sulfate were 90.21% and 14.36%, respectively. Fourier transform infrared spectroscopy and Ion chromatography were used to analyzed the structure and the monosaccharide of the product, and the results showed that characteristic of the product was in conformity with that of Sigma's standard sample.The strong antioxidant activity of chondroitin sulfate was evaluated by chemical methods. Chondroitin sulfate could scavenge the superoxide radical, hydroxyl radical and DPPH free radical. Its scavenging activity was positively correlated with the concentration of chondroitin sulfate. The reduction capacity of chondroitin sulfate was enhanced with the increase of chondroitin sulfate concentration.