Extraction of polysaccharides and its antitumor activity on Magnolia kwangsiensis Figlar & Noot.

• The crude polysaccharides from the leaves of Magnolia kwangsiensis Figlar & Noot. were extracted by hot water extraction.
• Two homogeneous polysaccharides were obtained by DEAE-52 cellulose chromatography and Sephadex G-100 column chromatography.
• P-2 and P-3 were characterized by IR, HPGPC and GC–MS.
• The antitumor activities of P-2 and P-3 were evaluated.
• P-3 with stronger antitumor activities was found.

The crude polysaccharides from the leaves of Magnolia kwangsiensis Figlar & Noot. were extracted by hot water extraction, the yield was 5.09%. Two polysaccharide fractions (P-2 and P-3) were isolated by DEAE-52 cellulose chromatography and Sephadex G-100 column chromatography in order, respectively. P-2 and P-3 were characterized by IR, HPGPC and GC–MS. P-2 was comprised of only glucose. Its molecular weight was 11.2 × 103 Da and the formula was C414H690O345. P-3 was comprised of xylose and rhamnose in the ratio of 1:4. Its molecular weight was 7.8 × 103 Da, and the formula was C319H528O220. The antitumor activities of P-2 and P-3 on the growth of human lung cancer (A549) cells and human gastric carcinoma (SGC7901) cells in vitro were evaluated. The results indicated that P-3 exhibited marked antitumor activities with IC50 value of 8.48 and 5.66 μg/mL.