Structural analysis and anti-tumor activity comparison of polysaccharides from Astragalus

Two polysaccharides; APS-I and APS-II, were obtained after a successive purification consisting of (1) fractional precipitation using ethyl alcohol; (2) filtration through DEAE-Sephadex A-25 and Sephadex G-100 eluted by water. The molecular weights of APS-I and APS-II were 4.77 x 10(6) and 8.68 x 10(3) Da, respectively, and they were mainly composed of glucose, and a small amount of arabinose and xylose, with their molar ratios of 0.54:1:18.14 and 0.23:1:29.39, respectively for APS-I and APS-II. FTIR, methylation, periodate oxidation, Smith degradation, H-1 NMR and C-13 NMR were used in their structure analysis. The results indicated that structurally, APS-I and APS-II were similar, with their main chains mainly composed of major alpha-(1 -> 3) glucose and a few 1 -> 4, 1 -> 6 glucoses, while the side chain contained arabinoses and xyloses. The tumor inhibition ratios of APS-I and APS-II were 55.47% and 47.72%, respectively. (C) 2011 Elsevier Ltd. All rights reserved.