Polysaccharides from Cymbopogon citratus with antitumor and immunomodulatory activity

Context: Most of the present studies on the antitumor efficiency of Cymbopogon citratus (DC.) Stapf (Gramineae) are limited to its low-mass compounds, and little information about the antitumor activity of polysaccharides from this plant is available. Objectives: This study focused on the potential antitumor and immunomodulatory activities of polysaccharides (CCPS) from C. citratus. Materials and methods: CCPS was isolated using the water extraction-ethanol precipitation method. The sarcoma 180 (S180) cells-inoculated mice were intraperitoneally administrated with CCPS (30-200 mg/kg/d) for seven consecutive days. The effects of CCPS on tumor growth, thymus and spleen weights, splenocyte proliferation, and cytokine secretion in the tumor-bearing mice were measured. The cytotoxicity of CCPS (50-800 mu g/mL) towards S180 cells was also studied. Results: CCPS significantly inhibited the growth of the transplanted S180 tumors, with the inhibition rates ranging from 14.8 to 37.8%. Simultaneously, CCPS dose-dependently improved the immunity of the tumor-bearing mice. With the highest dose of 200 mg/kg/d, the thymus and spleen indices were increased by 21.9 and 91.9%, respectively; ConA-and LSP-induced splenocyte proliferations were increased by 32.7 and 35.3%, respectively. The secretions of interleukin 2 (IL-2), interleukin 6 (IL-6), interleukin 2 (IL-12), and tumor necrosis factor-alpha (TNF-alpha) were increased by 103.2, 40.2, 23.6, and 26.3%, respectively. Nevertheless, almost no toxicity of CCPS towards S180 cells was observed, with the maximal inhibition rate less than 15% at the CCPS concentration of 800 mu g/mL. Conclusion: CCPS exhibited antitumor activity in vivo, and this activity might be achieved by immunoenhancement rather than direct cytotoxicity.