Study On Degradation Of Chondroitin Sulfate And Antioxidant Activity Of Its Products

Chondroitin sulfate?CS?is a kind of linear sulfated mucopolysaccharides which exist in connective tissue of animals widely.Research shows chondroitin sulfate has many biological activities,such as antioxidation,anticoagulation,lowering blood lipid,antarthritic and immunomodulation.At present,at home and abroad,the research on chondroitin sulfate is mainly focused on extraction,content determination and biological activity,but there are few researches on low molecular weight chondroitin sulfate.Low molecular weight chondroitin sulfate is more favorable to be absorbed by organism and has potential application value in biomedicine and so on.Therefore,the research on low molecular weight chondroitin sulfate has great significance.Based on this,the chondroitin sulfate was extracted from bovine nasal cartilage as raw material,and the purified components were degraded by oxidative degradation method.The physicochemical properties and antioxidant activities which different components were compared before and after degradation,which provided scientific basis for the development and application of chondroitin sulfate with different molecular weight.The main findings are as follows:1.Extraction and purification of Chondroitin sulfateChondroitin sulfate was extracted by complex enzymatic method and purified by DEAE-cellulose column chromatography to give three components:CS-?,CS-?,CS-?I.Among them,CS-? has the highest yield,accounting for 54%of the total yield.The monosaccharide compositions of CS,CS-?,CS-?,CS-?I were determined by HPLC,all of them were mainly composed by GlcUA,GalN and Gal.The average molecular weight of the standard sample,CS and CS-?,CS-?,CS-?I were 115.5 kDa,116.3 kDa,88.3 kDa,129.4 kDa,273.8 kDa,respectively,the sulfate groups contents were 23.42±0.41%,20.21±0.37%,2.10±0.53%,16.76±0.69%,21.14±0.56%,respectively.The uronic acid contents were 41.31±0.83%,30.40±0.90%,8.43±0.71%,31.32±0.69%,29.81±0.78%,respectively.The results showed that the content of uronic acid and sulfated group of CS-? was the lowest and its average molecular weight was much smaller than that of standard sample.The content of sulfate group of CS-?I was high,but its average molecular weight was much higher than that of standard sample,and the content of uronic acid of CS-? was the highest,the content and molecular weight of sulfated group were similar to the standard.Therefore,the CS-?,a component with a higher rate,was late selection to degrade and activities were studied.2.Screening of degradation conditions for CS-?The H₂O₂-Vc oxidative degradation system was used to degrade the purified CS-? components.Different molecular weight fractions were obtained by changing the concentration of H₂O₂ and Vc.The results showed that the concentration of Vc could significantly affect the molecular weight of CS-?.Through screening,four degraded components,CS-?-1:92.7 kDa,CS-?-2:54.1 kDa,CS-?-3:26.3 kDa,CS-?-4:19.7 kDa were selected for infrared spectrum analysis and physical and chemical properties determination.Infrared spectrum analysis results show that the components before and after degradation,all of them had characteristic absorption peaks of chondroitin sulfate,indicating that the oxidative degradation system did not destroy the main structure of CS-?.The results of physical and chemical properties showed that there was no significant difference in sulfate content before and after degradation,which were 16.73±0.26%,16.45±0.21%,16.59±0.56%,16.40±0.42%,16.75±0.77%,respectively.The content of uronic acid was 41.51±0.63%,37.24±0.98%,35.65±0.95%,36.18±0.72%,higher than that of CS-??31.32±0.51%?,respectively.It was found that the composition of monosaccharide was composed of GlcUA,GalN and Gal before and after degradation,but the molar ratio of GlcUA of each component increased,which was consistent with the results of colorimetry.In order to further explore the biological activity difference of different molecular weight components,CS-? and degradation components were selected to study the antioxidation activity at the later stage.3.Comparison of the antioxidant activity of CS-? and its degradation productsThe superoxide anion?.O2^-?,hydroxyl radical?.OH?,DPPH and reduction ability of CS-? and its degradation products were determined.The results showed that CS-? and its degradation components had certain antioxidant activity in a concentration-dependent manner.In addition,the antioxidant activity of the four degradation components was higher than that of CS-?,and the lowest molecular weight component CS-?-4 had the strongest antioxidant activity,and the scavenging ability of DPPH radical was up to74.78%.