Abstract:

Improved chlorosulfonic acid/pyridine and HCl/methyl alcohol methods were used for sulfurizing and desulfurizing native Gracilaria lemaneiformis polysaccharides, respectively. The immunoregulatory effects of sulfurized, desulfurized and native Gracilaria lemaneiformis polysaccharides in mice with low immunity induced by cyclophosphamide were investigated. Compared with the model group, native Gracilaria lemaneiformis polysaccharides were the most effective in improving spleen index (P＜0.05), phagocytic activity of macrophages (P＜0.05), proliferation and transformation of spleen cells (P＜0.05) and NK cell killing activity (P＜0.01), followed by sulfurized and desulfurized ones. All three polysaccharides could significantly improve the formation of hemolysin and hemolytic plaque in immunosuppressive mice (P ＜ 0.01), native and sulfurized Gracilaria lemaneiformis polysaccharides were superior to desulfurized ones. Based on these results, it can be concluded that Gracilaria lemaneiformis polysaccharides significantly increase the immune function in immunocompromised mice, that sulfate content in Gracilaria lemaneiformis polysaccharides is nonlinearly related to their immunoregulatory effect in immunocompromised mice, and that both sulfurization and desulfurization decrease the immunoregulatory effect of native Gracilaria lemaneiformis polysaccharides, especially desulfurization resulted in a significant decrease.

Key words: polysaccharides from Gracilaria lemaneiformis, sulfate, immunocompetence