Abstract: The aim of the present study was to examine the antitumor and immunoenhancing effects of two polysaccharides (POP II and POP III) isolated and purified from Portulace oleracea L. in Lewis lung tumor-bearing mice. The mice subcutaneously implanted with Lewis lung tumor cells on their toes were intraperitoneally injected with each polysaccharide at doses of 100 and 50 mg/kg (body weight) for 10 days, respectively. Meanwhile, cyclophosphamide (CTX) was used as antitumor positive control, and Coriolus versicolor polysaccharopeptide was used as immunoenhancing positive control, and the same volume of normal saline was used as negative control. The results showed that the tumor growth inhibition rates of POP II were 35.10% and 41.01%, while those of POP III were 36.91% and 45.11% at the low and high doses, respectively. Both treatment groups were significantly different from the negative control (P < 0.05). Moreover, POP II and POP III exhibited a stimulating effect on the cytotoxicity of natural killer (NK) cells with a significant difference when compared with the negative control (P < 0.05). Meanwhile, both of them could accelerate the conversion of lymphocytes with a stimulation index of 1.27–1.33, showing significant differences when compared with the negative control (P < 0.05). In a word, POP II and POP III can improve thymus index and spleen index in normal mice and thus play a significant role in antitumor and immunoenhancing functions.

Key words: Portulace oleracea L., polysaccharide, antitumor, immunoenhancing