Structural features and complement fixing activity of polysaccharides from Codonopsis pilosula Nannf. var. modesta L.T.Shen roots

Two pectic polysaccharides, 50WCP-II-I and 100WCP-II-I, were obtained from 50 and 100 °C water extracts of Codonopsis pilosula roots by ion exchange chromatography and gel filtration. The study of the sub-fractions obtained after pectinase degradation showed that the complement fixation activities of these pectins are expressed mainly by their ramified regions. The structure studies of native and sub-fractions showed the 50WCP-II-I is a pectic polysaccharide, with long homogalacturonan regions (some of the galacturonic acid units were methyl esterified), interrupted by one short rhamnogalacturonan I (RG-I) region. The side chains of the RG-I region are arabinogalactan type I (AG-I) and type II (AG-II) attached on position 4 of rhamnose. The 100WCP-II-I has two main ramified regions, one is galacturonan region with AG-I side chain on position 2 of GalA, and the other one is RG-I region with AG-II side chain on position 4 of Rha.