Study On The Isolation, Purification And Bioactivity Of Carbohydate From Smallanthus Sonchifolius

Yacon (Smallanthus Sonchifolius) is dicotyledonous herbage from helianthus of the composite, which was originally cultivated in South America in the Andean highlands. Yacon is rich in active ingredients including polysaccharides, flavonoids, phenolic acids and essential oil, and also has comprehensive utilization value in edibility and medicine.The crude polysaccharide and oligosaccharide were extracted by boiled water and precipitated by ethyl alcohol from yacon. With extraction temperature, the ratio of material to solvent, extraction time, different concentrations of ethanol as effect factors, on the basis of single factor test, the orthogonal test was taken to study the optimum extraction technology of crude polysaccharide in yacon. The optimum conditions for the extraction of crude polysaccharide in yacon were extraction temperature90℃, the final concentration of ethanol80%(v/v), the ratio of material to solvent1:15(g/mL), extraction time2h. The protein was removed by the method of Sevage and pigment was eliminated by macroporous resins. One kind of polysaccharide, named YPS-Ia, was obtained after purified by DEAE-Sephadex A-25and Sephadex G-100. The total carbohydrate content of YPS-Ia was93.6%. There was no absorption in UV spectrum showed that YPS-Ia didn’t contain protein and nucleic acid. YPS-Ia with the relative molecular weight9.26×10Da was identified by HPLC. The structure of YPS-Ia was analyzed with chemical methods. From FT-IR, YPS-Ia was polysaccharide. The results of GC indicated that YPS-Ia consisted of arabinose, xylose, mannose and glucose with a molar ratio of12.8:11.8:52.5:21.7.The qualitative and quantitative analyses were performed on crude oligosaccharides extracted from yacon by TLC and HPLC. The results showed that the crude oligosaccharides consisted of D-glucose, fructose, sucrose,1-kestosed, nystose and the contents of them in crude oligosaccharides were38.30%,16.44%,14.58%,12.29%,12.17%, respectively.1-kestosed and nystose were separated from crude oligosaccharides by Silica gel column chromatography. The purity of1-kestosed was82.9%and nystose was73.6%.The experiment method of the preventive hyperlipemia animal model was applied to investigate the hypolipidemia activity of carbohydrate from yacon. The results were follows:the carbohydrate from yacon had no obvious effect on mice weight; the crude polysaccharide, YPS-Ia and crude oligosaccharides could remarkably inhibit the rising of blood lipid, effectively decreased TC, TG and LDL-C in the serum(p<0.01); comparing with the other groups. YPS-la group could obviously increase HDL-C(p<0.05) in the serum; and YPS-Ia group had effect on decreasing TG and TC(p<0.01) in the liver of mice. The results showed that the carbohydrate from yacon could obviously inhibit the rising of blood lipid and YPS-Ia had better effect than the crude polysaccharide and oligosaccharides. They effectively prevent the hyperlipemia.