Study On Isolation,Identification And Biological Activity Of Polysaccharides Derived From Bulbils

Bulbils,commonly known as "yam eggs",are the seeds of yam and mainly made up of the starch,polysaccharides(including mucus and glycoprotein),protein and a variety of free amino acids,allantoin,choline and other ingredients.At present,most of bulbils have been abandoned and caused a waste of resources because there is only a small amount of them were used as seeds,food and herbs.In recent years,polysaccharides have been widely studied as one of the hotspots because of their wide source and antioxidant,hypolipidemic,hypoglycemic,antibacterial and other active functions.It has been proved that the polysaccharide from bulbils has good anti-oxidation and hypoglycemic effects.In order to provide experimental basis for the development and utilization of bulbils,the following work is focused on the isolation,identification and bioactivity of polysaccharide from bulbils in this paper.1.The ultrasonic assisted extraction technology of polysaccharide was optimized by response surface method on the basis of the single factor experiment.The optimum extraction parameters were as follows:the liquid to material ratio was 17.8:1(mL/g),ultrasonic power was 760.4 W,ultrasonic time was 22.9 min and the yield of crude polysaccharide was 61.94%(The mass of the powder is 3 g).The extract was purified by deproteinization.DEAE-52 column and Sephadex G-100 column chromatography and the eluates were obtained by eluted with water(PB-1)and 0.1 mol/L NaCl(PB-2),respectively.2.The purity and structure of the two polysaccharides were characterized.The results of ultraviolet spectrum showed that the polysaccharides were free of protein and nucleic acid.And they are both homogeneous polysaccharides according to the analysis results of Sephadex G-100 column chromatography and phenol-sulfuric acid method.In addition,the composition of monosaccharides was analyzed by high performance liquid chromatography.The results showed that PB-1 mainly consisted of mannose,rhamnose,glucose and galactose and the relative molar ratio was 2.19:1.56:1.78:0.78;PB-2 mainly consisted of rhamnose,glucose and xylose and the relative molar ratio is 4.24:3.73:9.63:13.36.Electron microscopy showed that PB-1 was rod-like,porous and PB-2 was inseparable and spiral.3.The antioxidant activities of the two polysaccharides were investigated and the results showed that PB-1 and PB-2 had different scavenging effects on DPPH,O2-· and OH.And the dose-dependent effect was observed in the range of the studied concentration.Furthermore,the scavenging effect of PB-1 on DPPH· and O2-· and reducing power were better than PB-2,but the scavenging ability of PB-1 and PB-2 on ·OH was close.4.The anti-fatigue activity of PB-1 was evaluated by exhaustive swimming time and biochemical indexes in mice.The low,middle and high dose groups can prolong exhaustion swimming time significantly;The levels of blood urea nitrogen,lactic acid and malondialdehyde in the three dose groups were significantly lower than those in the blank group.and middle dose group,respectively.The low and high doses of two groups can significantly increase liver glycogen reserves.These results indicate that the polysaccharides from bulbils have a good effect on anti-fatigue activity.