| There are vast sea areas and rich seaweed resources in Hainan.As a kind of natural active substance,seaweed contains polysaccharides,proteins,dietary fiber,vitamins and other nutrients.Seaweed polysaccharide has anti-oxidation,anti-tumor,anti-coagulation and other biological activities,and it is an important source of cosmetics and marine drugs.Sargassum carpophyllum(SC)and Caulerpa lentillifera(CL)are two common types of seaweed in Hainan.This paper studied the extraction,structure and antioxidant properties of these two kinds of seaweed polysaccharides.Adsorption properties of heavy metal ions by two seaweed residues and their carboxyl derivatives were also investigated to provide more theoretical basis for the development and utilization of marine algae resources in the South China Sea.In this paper,the ultrasound-assisted NaOH solution was used to extract polysaccharides from SC and CL.The effect of several single factors such as ratio of liquid to solid,extraction temperature,and extraction time on polysaccharide extraction rate was explored.The Box-Behnken Center design test in Response Surface Methodology was used to optimize ultrasonic-assisted extraction of these two types of seaweed polysaccharides by Design-Expert.V8.0.6 software.(1)The highest extraction rate of SCP was 16.8%under the optimum conditions of liquid to solid ratio of 49:1,extraction temperature of 71?,and extraction time of 6 h.The SCP was purified by DEAE-52 cellulose and obtained two kinds of fine polysaccharides which are SCP-1 and SCP-2.The molecular weights of SCP-1 and SCP-2 were measured by Gel Permeation Chromatography(GPC),which were 151 KDa and 125KDa,respectively.Physical and chemical properties analysis showed that the polysaccharide contents of SCP-1 and SCP-2 were 60.2%and 80.4%,the protein contents were-0.805%and 1.24%,the uronic acid contents were 5.83%and 18.01%and the sulfate contents were 0.72%and 0.28%,respectively.The pre-column derivatization of PMP-HPLC showed that the monosaccharide composition of SCP-1 and SCP-2 was very similar.They both contained mannose,glucuronic acid and glucose,but the monosaccharide contents were different.By periodate oxidation reaction,it was speculated that there were oxidized bond types like 1?,1?6,which accounted for 25.2%and 1?2,1?2,6,1?4,1?4,6 accounted for 49.2%;there were non-oxidized bond types like 1?3,1?2,3,1?2,4,1?3,4 or 1?2,3,4,which accounted for 25.6%in SCP-1.There were oxidized bond types like 1?,1?6,which accounted for 14.3%and 1?2,1?2,6,1?4,1?4,6 accounted for 54.8%;there were non-oxidized bond types like 1?3,1?2,3,1?2,4,1?3,4 or 1?2,3,4,which accounted for 30.9%in SCP-2.The antioxidant activity was tested by scavenging hydroxyl radicals,DPPH radicals,ABTS radicals,and superoxide radicals in vitro.The results showed that the radical scavenging rate gradually increased with the concentration of samples increased and the SCP-2 has stronger antioxidant activity than SCP-1,When the concentration was 10 mg/mL,the hydroxyl radical scavenging rate of SCP-2 reached for 54.77%,the DPPH radical scavenging rate was 65.2%,the ABTS radical scavenging rate was close to 90%,and the superoxide radical scavenging rate reached to 70.8%.(2)The highest extraction rate of CLP was 11.8%under the optimum conditions of liquid to solid ratio of 42:1,extraction temperature of 72?,and extraction time of 6 h.The CLP was purified by DEAE-52 cellulose and obtained the fine polysaccharide named CLP-1.The molecular weight of CLP-1 was 115KDa measured by GPC.Physical and chemical properties analysis showed that the polysaccharide,protein,uronic acid,sulfate contents of CLP-1 were 58.5%,-0.31%,14.1%and 27.4%,respectively.The pre-column derivatization of PMP-HPLC showed that the CLP-1 was mainly composed of xylose and galactose,which together account for 90%of the total polysaccharide,there was also a small amount of glucose and uronic acid.By periodate oxidation reaction,it was speculated that there were oxidized bond types like 1?,1?6,which accounted for 23.3%and 1?2,1?2,6,1?4,1?4,6 accounted for 18.1%;there were non-oxidized bond types like 1?3,1?2,3,1?2,4,1?3,4 or 1?2,3,4,which accounted for 58.6%in CLP-1.In vitro anti-oxidation experiments showed that CLP-1 has a weaker activity for scavenging free radicals than SCP-1 and SCP-2.In this paper,the waste residues from the extraction of seaweed polysaccharides were used to determine the composition of the residues by Van Soest's defibration fiber analysis method.To modify the seaweed residues with succinic anhydride,the adsorption properties of heavy metal ions before and after the modification were tested to determine the best adsorption conditions.(1)The moisture,hemicellulose,cellulose,lignin and ash content of SCR were 7.2%,25.83%,12.49%,30,53%and 0.36%,respectively.Succinic anhydride was used for carboxyl modification of SCR.Under the optimum conditions of 1.5 g succinic anhydride,0.07 g NBS,reaction time of 6 h and extraction temperature of 70?,the degree of substitution of carboxyl group reached for highest.At this time,it reached the maximum saturated adsorption capacity of heavy metals contained Cu2+,Pb2+,Cd2+,Mn2+ and the adsorption capacity of Pb2+ reached to 105 mg/g.(2)The moisture,hemicellulose,cellulose,lignin and ash content of CLR were 13.29%,15.69%,29.87%,16.1%and 0.41%,respectively.Succinic anhydride was used for carboxyl modification of CLR.Under the optimum conditions of 1.5 g succinic anhydride,0.07 g NBS,reaction time of 6 h and extraction temperature of 60?,the degree of substitution of carboxyl group reached for highest.At this time,it reached the maximum saturated adsorption capacity of heavy metals contained Cu2+,Pb2+,Cd2+,Mn2+ and the adsorption capacity of Pb2+ reached to 108.8 mg/g. |
PDF Full Text Request