Study of Polysaccharide of Nostoc Commune

Nostoc Commune as raw material,after refluxing with methyl alcohol for 5 h to remove fatty materials,was extracted 3 times by water at 98 ℃ for 3.8 h.The combined raffinate was concentrated under vacuum,protein removed by proteolytic enzyme once and by Sevag method 7 times,and dialyzed by distilled water for 2 d.By adding 3 times volume of φ (CH 3CH 2OH)=95% alcohol,polysaccharides were precipitated and freeze dried.Then the dried mass was dissolved in boiling water,three water soluble polysaccharides(SP-1,SP-2 and SP-3) were obtained by QAE-sephadex-A-25 chromatography.SP-2 was shown to be homogenenous by sephadex G-100 chromatography and acetate film electrophoresis.Molecular weight of SP-2 was estimated to be 8 82×10 4 by HPLC.After hydrolysis,SP-2 was found by GC to consist of only one kind of monosaccharide,viz. glucose.Infrared spectrum indicated that SP-2 has β glycosidic linkage of D glycopyranoside.Results of biological activity tests showed that at concentration of 0 5,5 and 2 mg/L,SP-2 increased the germination rate of the seeds of Brassica juncea,cockscomb and Lycopersicum esculentum by 14%,12% and 9% respectively as compared with the controls.