Synthesis And Bio-activity Study Of Seleno-polysaccharide

Sulfated polysaccharide was extracted from Eucheuma gelatinae with distilled water, precipitated with ethanol. FT IR spectrum of the polysaccharide indicated that it is κ-carrageenan. Seleno-polysaccharides were prepared by employing sodium selenite to modify the polysaccharide under the catalysis of HNO₃-BaCl₂ or HNO₃. Dialysis was applied to remove the excess sodium selenite. It was about 24hrs to stop dialysis when the red detected by ascorbic acid stopped to appear. The favor reaction conditions were at 70℃ for 10 hours in the presence of 0.5% volume concentration of nitric acid. The selenic content determined by ICP of seleno-polysaccharide obtained under such condition was 0.413mg/g, while the yield of seleno-polysaccharide was 0.73 %. The absorption bands of seleno-polysaccharide at 930 and 850 cm^-1 became weak after dialyzing. The reason is part of the macromolecular polysaccharide can be decomposed to form oligosaccharide which can be remove by dialysis in the presence of nitric acid. Selenite is bonded mainly to the oligosaccharide by comparing selenium contents in seleno-polysaccharides obtained under different reacting conditions and after dialyzing for different time. ¹³C-NMR confirmed the structural difference between seleno-polysaccharide and polysaccharide. The effects catalyzed by HNO₃-BaCl₂ or HNO₃ on seleno-polysaccharide are similar. Thus, nitric acid can only be used as catalyst by improving the reported method. Excess selenite in the seleno-polysaccharide catalyzed by nitric acid was reduced by ascorbic acid, and nano-selenium dispersed by seleno-polysaccharide was prepared.The inhibiting effects of seleno-polysaccharide and nano-selenium dispersed by seleno-polysaccharide on HEp-2, K562, and H460 were studied by MTT method. The results showed that seleno-polysaccharide significantly inhibited the proliferation of HEp-2 cells in vitro. Compared with natural polysaccharide or sodium selenite containing the same amount of Se, the seleno-polysaccharide was more effective. Seleno-polysaccharide was more effective on K562 and H460 cells than natural polysaccharide, but less effective than sodium selenite in the same amount. The inhibition relies on the concentration of the seleno-polysaccharide. Nano-selenium dispersed by seleno-polysaccharide revealed...