Chemical characterization and in vitro antitumor activity of a single-component polysaccharide from Taxus chinensis var. mairei

•This work is the first time reported in research of structure and bioactivity of an alkali-soluble single-component polysaccharide (named CPTC-2) isolated and purified from Taxus chinensis var. mairei by ion-exchange and gel-permeation chromatography in series.•The authors used a variety of methods to analyze the structure properties of polysaccharide and get a fully understanding of the structure of CPTC-2. Moreover, the combination of MTS assay and flow cytometry method was adopted to study the antitumor function of CPTC-2.•Finally, the partial relationship between structure of the polysaccharide and its antitumor activity was obtained. An alkali-soluble single-component polysaccharide, named CPTC-2, was isolated and purified from the leaves of Taxus chinensis var. mairei. by ion-exchange and gel-permeation chromatography in series. The weight-average molecular mass (Mw) of CPTC-2 was about 73.53kDa determined by gel permeation chromatography (GPC). The structural characteristics of CPTC-2 were analyzed by gas chromatography (GC), Infrared (IR) spectrum, nuclear magnetic resonance (NMR) spectroscopy, periodate oxidation and Smith degradation studies, as well as methylation analysis. The results showed that CPTC-2 consisted of glucose, mannose, xylose, arabinose, rhamnose, and galactose with a molar ratio of 1.00:0.32:0.27:3.34:1.22:1.84. CPTC-2 was mainly composed of one type of sugar, α-glycosidic linkage. It had a backbone composed of α-(1→3) Araf, α-(1→5) Araf and α-(1→4) Galp with branches composed of α-(1→3,5) Araf and β-(1→3,6) Manp. In vitro anti-tumor experiments with SGC-7901 cells were performed and assessed by MTS (MPEG-2 Transport Stream) method and flow cytometry. The results showed CPTC-2 could inhibit the growth of SGC-7901 cells in a concentration-dependent manner via increased apoptosis. The relationship between the structure of CPTC-2 and its anti-tumor activity indicated that the α-configuration glycosidic bond residues may be essential for the anti-tumor activity of this polysaccharide.