Preparation And Antioxidant Activity Of Polysaccharide From Artemisia Integrifolia

Plant polysaccharides are rich in biologically active functions without cytotoxicity and have become one of the hot research topics today.In this study,a response surface methodology was used to optimize the process conditions for the extraction of polysaccharide from Artemisia integrifolia by ultrasonic-assisted enzymatic method;exploring the effects of different treatments on the polysaccharide solubility and antioxidant activity of Artemisia integrifolia;and explore its antioxidant activity by H₂O₂-induced Hep G2 cell assay.The main findings of the study are as follows:（1）Preparation of polysaccharide from Artemisia integrifolia.The extraction process of Artemisia integrifolia polysaccharide was optimized by orthogonal and response surface tests with the integrated value as the evaluation index and the extraction sequence,ultrasonic time,ultrasonic power,solid-liquid ratio and enzyme addition as the variables.The optimum extraction process was as follows:ultrasonic followed by enzymatic digestion,ultrasonic power of 300 W,solid-liquid ratio of 1:30 g/m L,ultrasonic time of 46 min,cellulase of 2.0%,pectinase of 3.0%,and the yield of polysaccharide was 7.67%.（2）Effect of different treatments on the polysaccharide properties of Artemisia integrifolia.The effects of different temperature,ultrasonic conditions and p H on the solubility,total antioxidant capacity,DPPH scavenging capacity and hydroxyl scavenging capacity of polysaccharides were studied,and comprehensive evaluation was made by entropy weight method.The results showed that the increase in temperature led to an increase in polysaccharide solubility and decreased antioxidant activity;suitable ultrasonic treatment has little effect on the antioxidant activity of polysaccharides;the antioxidant activity of acid-treated polysaccharides is higher than that of alkali-treated polysaccharides;The entropy-weighted analysis of 20treatments and 4 indicators showed that solubility was the main indicator affecting the overall score,and the highest overall score was obtained for Artemisia integrifolia polysaccharide treated with ultrasonic wave at 240 W for 30 min.（3）Study on antioxidant activity in vitro.Two components,AIP-2 and AIP-3,were separated from the crude polysaccharide of Artemisia integrifolia for follow-up study.By comparing the IC₅₀ values of total antioxidant capacity,DPPH scavenging capacity and hydroxyl scavenging capacity,we can see that the order of antioxidant capacity of the samples was:Vc>AIP-3>AIP-2>crude polysaccharide.The antioxidant activities of AIP-2 and AIP-3 were investigated by establishing a model of H₂O₂-induced oxidative damage in Hep G2 cells.The results showed that the modeled concentration of H₂O₂-induced Hep G2 cells for 4 h was 200μmol/L.Compared with the model group,high concentrations of AIP-2 and AIP-3 treatment increased cell survival by 54.35%and 60.26%,superoxide dismutase（SOD）activity by 35.86%and 38.98%,catalase（CAT）activity by 173.02%and 205.42%,glutathine peroxidase（GSH-Px）activity by 50.24%and 50.78%,and decreased malonyldialdehyde（MDA）content by 46.13%and 53.87%.It was shown that both AIP-2 and AIP-3 could protect Hep G2 cells from oxidative damage,with AIP-3 having a better effect.（4）The molecular weight,monosaccharide composition and thermal stability of A IP-3 were determined.The results showed that AIP-3 was a heteropolysaccharide with good thermal stability,and its average molecular weight was 2.70×10⁴ Da.It consists of Glc,Rib,Gal,Rha,Xyl,Ara,Man,GlcA,Man A,Fuc and Glc N with molar ratios of 0.315:0.226:0.189:0.108:0.058:0.040:0.036:0.017:0.006:0.002:0.002.It is hypothesized th at the lower molecular weight and higher glucose and galactose content of AIP-3 lead to a stronger antioxidant capacity.