Subcritical Water Extraction,purification,structure Characterization And Antioxidant Activity Analysis Of Cornus Officinalis Seed Polysaccharide

Cornus officinalis is a famous medicinal plant in China,which is distributed in Shanxi,Henan,Hunan and other provinces.The pulp is traditionally used as a tonic,anti-inflammatory food to improve liver and kidney function and is used in traditional Chinese medicine to treat diabetes,cancer and shock.The Cornus officinalis seed is the kernel left by the fruit of Cornus officinalis,which is rich in polysaccharide,protein,tannin and oil and other ingredients.Up to now,the utilization rate of the seeds of Cornus officinalis is very low,and there are few reports on the study of polysaccharides from the seeds of Cornus officinalis.In order to further understand the physicochemical properties,structure and antioxidant activity of polysaccharides from the seeds of Cornus officinalis,subcritical water extraction,subcritical water degradation kinetics,separation,purification and structure characterization of polysaccharides were carried out in this study,and antioxidant activity was studied and analyzed.The main research contents are as follows:In order to isolate and purify,characterize the structure and study the antioxidant activity of polysaccharides from Cornus officinalis seeds,this study prepared polysaccharides from Cornus officinalis seeds by hot water extraction and subcritical water method.Taking the yield of polysaccharides from Cornus officinalis seeds as the index,the technological parameters were optimized and the optimal extraction method was compared and selected.The optimized conditions of hot water extraction were as follows:extraction time 2.0 h,extraction temperature 80?,liquid-solid ratio 20:1 m L/g,mesh number 60.The yield of polysaccharide from Cornus officinalis seed was 9.51%.After optimized by subcritical water method,the extraction temperature was 148?,the number of mesh was60 mesh,the ratio of liquid to solid was 38.3:1 m L/g,and the extraction time was 21 min.The polysaccharide yield was 17.25%.The subcritical water degradation of Cornus officinalis seeds was studied.The reducing sugar content of the liquid product was measured at different degradation temperatures and degradation times.The Saiman model was used to simulate and analyze the degradation kinetics equation,and the degradation kinetics parameters were obtained.The results showed that the Saeman model could well reflect the subcritical water degradation process of Cornus officinalis seeds.The reaction activation energy E_a1 of initial degradation was 29.47 k J/mol,the activation energy E_a2 of reducing sugar degradation was 22.21 k J/mol,the pre-exponential factor K₁₀ was 101.49 min^-1 and K₂₀ was 20.28 min^-1.Under the degradation temperature of 160?and degradation time of 20 min,a higher yield of reducing sugar can be obtained.The composition,structure and antioxidant activity of crude polysaccharides from Cornus officinalis seeds prepared by subcritical water method were studied.The analysis of monosaccharide composition showed that the crude polysaccharides from the seeds of Cornus officinalis were mainly composed of glucose,xylose,galactose and galacturonic acid,and the total sugar content was as high as 78.82%.Scanning electron microscopy(SEM)and infrared spectroscopy(IR)analysis showed that the structure of polysaccharides was spherical structure with smooth surface,irregular particles and different particle sizes,which was pyran glycoside ring skeleton.The results of antioxidant activity analysis showed that the polysaccharides from the seeds of Cornus officinalis had good free radical scavenging ability.When the mass concentration was 1.0 mg/m L,the free radical scavenging rates of DPPH·,·OH and ABTS⁺·were 85.61%,63.40%and 76.20%,respectively.The crude polysaccharide was decolorized by hydrogen peroxide,deproteinized by Sevage method,separated and purified by DAE-52 cellulose chromatography,and five polysaccharide components were obtained,namely COSP-1,COSP-2,COSP-3,COSP-4and COSP-5.The main polysaccharide component COSP-4 was further purified by Sephadex G-100 gel chromatography.Gel chromatography and monosaccharide composition show that COSP-4 is the molecular weight of 2.03x10⁴ U acid polysaccharide components,composed of rhamnose,glucuronic acid,galacturonic acid,glucose,xylose and galactose,mole ratio was 0.96:0.18:5.48:0.28:1:10.70.Methylation reaction and NMR showed that COSP-4 contained 14 methylated sugars,and the residues contained both?-glycosyl and?-glycosyl.The monosaccharide structure with the highest content was 1,4,5-triacetyl-2,3-dimethyl xylose.Scanning electron microscopy(SEM)showed that COSP-4was irregular fragment structure,loose and porous,similar to sponge structure.Antioxidant activity experiments showed that COSP-4 had strong scavenging ability on DPPH·,·OH and ABTS+·free radicals.The IC₅₀ of COSP-4 against DPPH·,·OH and ABTS⁺·radical were 1.72±0.14 mg/m L,1.48±0.17 mg/m L and 2.87±0.27 mg/m L,respectively.These results will provide theoretical reference for further study of the structure-activity relationship of polysaccharides from Cornus officinalis seeds and development of potential functional foods,and provide reference for the application of polysaccharides from Cornus officinalis seeds.