Purification,Structure And Bioactivity Of Polysaccharides From The Umbilicaria

Umbilicaria is a symbiont both food and medicine fungal with algal,and its medicinal value is high.Its polysaccharide has a very strong anti-cancer,anti-tumor activity as an active substance and can enhance the body's immunity.However,reports about umbilicaria polysaccharides'(UPS)is less at present,and the research on extraction,purification,structure of UPS is also incomplete.This paper major studies the optimum extraction conditions of polysaccharides from umbilicaria,and explore the polysaccharide's purification,structure identification and antioxidant activity in initial.The extraction parameters of umbilicaria polysaccharides were studied in the First.Extraction temperature,extraction time,ratio of water to raw material and extraction times were selected in single-factor experiments.Based on the single factor experiments,the three factors like extraction time,extract temperature and the proportion of water to raw material were elected to do response surface analysis.When the extraction temperature of 84.83?,extraction time of 3.56 h and ratio of water to material of 20.64:1(mL/g)were adopted,the polysaccharides' yield was 13.37%.After the polysaccharides were isolated and purified,we can analyse the basic physicochemical of umbilicaria polysaccharides.UPS was chromatographed on a DEAE Cellulose-52 anion-exchange column to yield two peaks,UPS-1 and UPS-2.The recovery of UPS-1 and UPS-2 were 49.05%and 23.23%respectively.UPS-1 and UPS-2 were chromatographed on a Sephadex G-150 column,and the recovery of UPS-1-1 and UPS-2-1 were 42.17%and 42.6%respectively.The physicochemical properties of crude UPS,UPS1-1 and UPS2-1 were determined using the methods of chemistry and physics.For crude UPS,UPS1-1 and UPS2-1,the polysaccharides content was 43.68%,55.12%and 53.34%respectively.Protein content was 1.01%,0.31%and 0.28%respectively.The sulfuric content was 2.38%,4.07%and 5.02%.Uronic acid content was 6.50%,19.29%and 19.50%.The structure of umbilicaria polysaccharides was then analysized.The relative molecular weight and purity of the polysaccharides fractions were detected by high performance size exdusion chromatography(HPSEC).The results showed that the UPS-1-1 and UPS-2-1 were all single components and their relative molecular weight were 124.7kD and 249.4 kD respectively.After the umbilicaria polysaccharides' two purified fractions were derivatized,their monosaccharide compositions were analyzed by high performance liquid chromatography(HPLC).The monosaccharide composition and molar ratio of UPS-1-1 was mannose:rhamnose:glucose:galactose=0.59:3.12:93.09:3.03,and the monosaccharide composition and molar ratio of UPS-2-1 was mannose:glucose=20.66:79.34.Using potassium bromide tablet method,we can analysis the Infrared Spectroscopy of umbilicaria polysaccharides' two purified fractions.It was found that the two polysaccharide components exhibited typical absorption peaks in the 4000 cm-1?400 cm-1 range and contains sulfuric acid and carboxylic acid groups,which showed that they were polysaccharide.Using scanning electron microscope(SEM)to observe the surface morphology of UPS-1-1 and UPS-2-1,they showed smooth surface,which explain their intermolecular forces is strong.The shape of the two fractions was observed by Atomic Force Microscope(AFM).The results showed that they were aggregations of some sugar chains.The ultimate research is a preliminary study about the antioxidant activities of the Umbilicarias' crude polysaccharides and two purified fractions.Antioxidant activities in vitro of UPS,UPS-1-1 and UPS-2-1 were measured by using the chemical methods.Results showed that the crude UPS,UPS-1-1 and UPS-2-ls' reducing power was weak but they could scavenge hydroxyl radicals(OH)and superoxide oxygen radicals(O2-·).Crude UPS,UPS-1-1 and UPS-2-1 had some antioxidant activities in vitro.UPS-2-1 exhibited much higher antioxidant activities than crude UPS and UPS-1-1.