Purification And Antioxidant Activities Of Polysaccharides From Stems And Leaves Of Kiwifruit In Changbai Mountain

Actinidia arguta(Sieb.et Zucc.)Planch and Actinidia kolomikta(Rupr.et Maxim.)Planch were belong to Actinidiaceae and mainly distributed in the ChangBai Mountain.In this study,the polysaccharides from stems and leaves of Actinidia arguta and Actinidia kolomikta were comprehensively investigated,including extraction,purification,characterization of polysaccharides and antioxidant activities.The results were as follows:1.The extraction tecnology of polysaccharidesWith the yields of crude polysaccharide as the index,different extraction methods were used to extract the polysaccharides from the stems and leaves of Actinidia arguta and Actinidia kolomikta to select the the appropriate extraction method.Single test and Response Surface Methodology was used to optimize the extraction tecnology of polysaccharides from the stems and leaves.And the results are as follows:(1)The optimum condition of microwave-assisted extraction to extract the polysaccharides form the stems of Actinidia arguta were microwave time 40.03 min,microwave power 314.64 W,water to material ratio 59.02 mL/g,the predicted optimal yield of AAS was 2.90%.(2)The optimum condition of ultrasonic tecnology to extact the polysaccharides form the leaves of Actinidia arguta were ultrasonic time 40.00 min,liquid-solid ratio 40 mL/g and the ultrasonic power 900 W.Under the condition the yield of leaves polysaccharide was 4.50%.(3)The optimum condition of ultrasonic tecnology to extact the polysaccharides form the leaves of Actinidia kolomikta was that liquid-solid ratio,T10 basic speed extraction temperature,and extraction time were 17.38 mL/g,9500 r/min,43.36℃,10.27 min,respectively and the extraction yield was 6.40 %.2.Isolation,purification and preliminary characterization of polysaccharidesThe polysaccharides were applied to a DEAE Sepharose fast flow anion-exchange chromatography and Sephadex G-100 chromatography,using water and sodium chloride at different concentrations as eluent respectively to give eight polysaccharide fractions,named AAS-1-1,AAL-1-1,AAL-2-1,AAL-3-1,AKS-1-1 AKS-2-1,AKL-1-1 and AKL-2-1.The total polysaccharide contents of eight polysaccharides were 88.78%(AAS-1-1),80.46%(AAL-1-1),89.86%(AAL-2-1),85.78%(AAL-3-1),80.45%(AKS-1-1),82.66%(AKS-2-1),81.26%(AKL-2-1),90.23%(AKL-2-1)respectively.The contents of uronic acid of eight polysaccharides were 16.71%(AAS-1-1),18.74%(AAL-1-1),1.07%(AAL-2-1),0.65%(AAL-3-1),6.21%(AKS-1-1),1.02%(AKS-2-1),22.45%(AKL-2-1),6.65%(AKL-2-1),respectively.The protein contents were relatively low.The molecular weight of AAS-1-1,AAL-1-1,AAL-2-1,AAL-3-1,AKS-1-1,AKS-2-1,AKL-1-1 and AKL-2-1 were determined by high performance gel permeation chromatography,and the results were as follows: 103722(AAS-1-1),109629.8(AAL-1-1),62715(AAL-2-1),62381(AAL-3-1),125314.6(AKS-1-1),65574.58(AKS-2-1),354813.5(AKL-1-1),344839.7(AKL-2-1)Da,respectively.Infrared spectrum scanning results showed that AAS-1-1,AAL-1-1,AAL-2-1,AAL-3-1,AKS-1-1,AKS-2-1,AKL-1-1 and AKL-2-1 had characteristic absorption peak of polysaccharides.The monosaccharide compositions of polysaccharides were analyzed by HPLC.All the eight polysaccharides were composed of rhamnose(Rha),glucuronic acid(GlcA),galactose(Gal),glucose(Glu),galacturonic acid(GalA),xylose(Xyl)and arabinose(Ara)at different molar ratio.3.The antioxidant activity of polysaccharidesThe antioxidant activities of AAS,AAL,AKS,AKL,AAS-1-1,AAL-1-1,AAL-2-1,AAL-3-1,AKS-1-1,AKS-2-1,AKL-1-1 and AKL-2-1 were estimated by measuring the scavenging activities on hydroxyl free radical(?OH)and DPPH·.And the results showed that all the polysaccharides have the abilities of scavenging DPPH? and ?OH.And the scavenging activities were dependent on the mass concentration of polysaccharide samples.According to the concentration inhibiting 50% radical,the order of scavenging ability on ?DPPH by eight homogeneous polysaccharides is as follows: AAL-2-1 > AAL-1-1 > AAS-1-1 > AKS-1-1 > AKS-2-1 = AKL-1-1 > AKL-2-1 > AAL-3-1.The order of scavenging ability on ?OH by eight homogeneous polysaccharides is as follows: AAL-1-1 > AAS-1-1 > AAL-2-1 > AAL-3-1 > AKS-1-1 > AKS-2-1 > AKL-1-1 > AKL-2-1.These results showed that the antioxidant activity was directly related to the molecular weight of polysaccharides,the concentration of the uronic acid,the smaller the molecular weight,the higher the concentration of the uronic acid acid,the higher the antioxidant activity.It is shown that these polysaccharides have significant antioxidant activities and can be explored as a natural antioxidant for food and medicine.