Molecular Structure And Biological Activities Of The Cordyceps Militaris Polysaccharide

C. militaris is considered to be the suitable alternative of C. sinensis which was used as a valuable herb in Chinese for centuries. Polysaccharides were one of major bioactive constituents of C. militaris, which were the most important one. In recent years, the excellent immunomodulation, antitumor, and anti-oxidant effect of polysaccharides obtained from C. militaris had been recognized by researchers. And many studies had focused on polysaccharides from C. militaris. In order to exploit polysaccharides obtained from C. militaris, it is important to figure out structures, activities and the structure-function relationship of them.In this study, four kinds of crude polysaccharides were isolated from fruiting bodies of cultured Cordyceps militaris respectively grown on solid rice medium and silkworm pupa by hot water extraction and ethanol precipitation. Then four acidic polysaccharide fractions, CM-jd-CPS, CM-hs-CPS, CM-js-CPS and CM-jd(Y)-CPS were obtained through fractionating by ion exchange column (DEAE-cellulose-52) and gel filtration column (Sephadex G-100) chromatography.Results of spectra (UVS) and gas chromatograph (GC) showed these four acidic fractions were all composed by mannose, glucose and galactose, but there was a great difference in the mole ratio of each kind of monosaccharide in their polysaccharides. The mole ratio of mannose to glucose to galactose in CM-jd-CPS was 1.52:8.53:1.00, in CM-hs-CPS was 1.35: 8.34: 1.00, in CM-js-CPS was 1.06: 2.31: 1.00, and in CM-jd(Y)-CPS was 3.11: 1.00: 2.12. From the IR results, it can be concluded that CM-jd-CPS, CM-hs-CPS and CM-js-CPS had similar structures, which were a kind of sulfated polysaccharides containing acetamido group. And the monosaccharides composing them were pyranose, which linked byα-glycosidic linkage. On the other hand, CM-jd(Y)-CPS was a kind of carboxylated polysaccharide containing acetamido group. And the monosaccharides were pyranose, which linked byβ-glycosidic linkage.The results of in vitro antioxidant activities exhibited that CM-jd-CPS, CM-hs-CPS, CM-js-CPS and CM-jd(Y)-CPS showed strong free radical DPPH scavenging activities, strong Fe²⁺ chelating activities. At the concentration of 8 mg/ml, the DPPH·scavenging activity of them were 94 %,89 %,84 % and 93 % respectively, and the ferrous ion chelating activities of them were 72 %,85 %,55 % and 89 % respectively. In addition, these polysaccharides exhibited moderate reducing power. In vitro immunomodulating activities of these four polysaccharides were evaluated through MTT method. They all possessed does-dependently mitogen effect on mouse splenocyte, and could promote both murine T and B lymphocyte induced by Con A and LPS. But their mitogen effects were different from each other. The results showed, CM-jd(Y)-CPS possessed the strongest stimulating activity to mouse splenocyte and T lymphocyte which were promoted 41% and 17% repectively, while CM-hs-CPS had the strongest stimulating activity to B lymphocyte which were promoted about 11%.