Composition analysis and anti-proliferation activity of polysaccharides from Dendrobium chrysotoxum

Water-soluble polysaccharides (DCCP, DCPP) were extracted from the stems of Dendrobium chrysotoxum using boiling water and ultrasound. DCPP were successively purified by chromatography on DEAE-Cellulose-52 and Sephadex G-200 column, giving three major polysaccharide fractions termed DCPP-I, DCPP-I-a and DCPP-II. Among these fractions, DCPP-I-a exhibited the highest abundance (79.5%). The number-average molecular weight and weight-average molecular weight of DCPP-I-a were 67 kDa and 122 kDa, respectively. Monosaccharide components analysis indicated that DCPP-I-a were composed of xylose, glucose, galactose in a molar ratio of 1.44:6.93:12.79. Infrared spectra (IR) and (1)H NMR showed that DCPP-I-a was composed of a β-D pyran ring with a β-configuration. The evaluation of anti-proliferation activity suggested that DCPP-I-a and DCPP-II had a higher inhibitory effect on the SPC-A-1 cells than DCCP as determined with in vitro anti-proliferation test.