Lotus Polysaccharides And Antioxidant Activity

The Chinese traditional medicine "Lien Tze Hsin", identified as embryo loti, Nelumbo nucifera GAERTN. is the embryo of the seed of lotus. It has been used for nervous disorders, insomnia, high fevers with restlessness and hypertension. In this thesis, the water soluble polysaccharides were extracted from the dry embryo Loti, then isolated, purified, and their structure analysis and antioxidant activity were investigated. The details were showed below:1. After grinding and removing lipids from embryo loti, the polysaccharides were extracted with boiling water and precipitated by 95% ethanol. The precipitates were deproteined by neutroenzyme and Sevag method to afford crude polysaccharides. The crude polysaccharides revealed to be heteropolysaccharides by acid hydrolysis and GC-MS were made up of L-arabinose(trace), D-xylose, D-mannose and D-galactose, among which D-xylose occupied a predominant proportion of 62.6%. IR spectrum indicated that the crude polysaccharides hadβ-pyranose residue.2. After isolation and purification of crude polysaccharides, the fractions ELPS-I～ELPS-VII were obtained by DEAE-Cellulose-32 anion exchange, Sephacryl^TM S-200 and Sephadex G-100 gel-filtration chromatography used respectively or tandem.3. The purity of ELPS-VII was checked by Sephacryl^TM S-200 gel-filtration chromatography. The protein, polypeptide or nucleic acid in this sample were absent and detected by UV spectrum. The preliminary structure determination of ELPS-VII was carried out by IR, composition analysis, NMR spectroscopy(¹H NMR,¹³C NMR and DEPT135°). The results indicated that the neutral sugar composition of ELPS-VII was the same as the crude polysaccharides; only the molar ration was changed.α-pyranose andβ-pyranose residues were coexisting in ELPS-VII, and DEPT135°spectrum showed that ELPS-VII probably had (1â†'6)-linked glycosyl residue.4. The anti-lipid peroxidative activity of crude polysaccharides was analyzed byβ-carotene bleaching assay, which showed that crude polysaccharides had significant antioxidative capacity compared with vitamine C as the positive control, and a dose-dependent increase had been observed in the range of 2-50 mg/mL. The glycosidoprotein also had antioxidative activity, but its effect was lower than the crude polysaccharides.In addition, an advance in research on embryo Loti and polysaccharides were summarized in this thesis.