The aim of the present study is to investigate the antitumor activity and immunostimulatory effect of the water-soluble polysaccharides (DDP) from stem of Dendrobium devonianum in S180 tumor-bearing mice. The mice were divided into 3 groups, and then DDP or Ganoderma lucidum polysaccharides (GLP) dissolved in deionized water were given to the mice at a dose of 200 mg kg−1 for 30 days. DDP, as well as GLP, significantly inhibited the growth of mouse transplantable tumors and promoted spleen indexes, delayed-type hypersensitivity reaction, natural killer cell activity, macrophage phagocytosis and lymphocyte proliferation. Moreover, DDP and GLP increased the colonic acetate, butyrate and total short-chain fatty acid (SCFA) concentrations. These results indicated that oral administration of DDP significantly inhibited the growth of transplanted tumors in S180 tumor-bearing mice by improving specific and non-specific immune responses, as well as increasing colonic SCFAs.
