小分子Rhizobium sp. N613胞外多糖的羧甲基化及其抗肿瘤活性

Carboxymethylation and antitumor activity of low molecular weight exopolysaccharide from Rhizobium sp. N613

目的建立小分子Rhizobium sp. N613胞外多糖羧甲基化的制备工艺并研究其抗肿瘤活性。方法以乙醇为溶剂,用一氯乙酸对小分子Rhizobium sp. N613胞外多糖(LREPS)进行羧甲基化修饰,通过正交试验考察了乙醇体积分数、一氯乙酸用量、氢氧化钠用量、醚化温度及时间对羧甲基化LREPS(CM-LREPS)羧甲基取代度(DS)的影响,并获得一系列CM-LREPS产物。红外图谱表征CM-LREPS分子结构。选取4组取代度(0.285,0.531,0.659和0.899)的CM-LREPS样品进行了小鼠肝癌腹水瘤H22抑瘤效果检验。结果红外图谱分析表明,实现了LREPS的羧甲基化。抗肿瘤试验表明,取代度为0.659的CM-LREPS效果最佳,抑瘤率高达59.2%。以取代度和抑瘤率为检测指标,确定CM-LREPS最佳制备工艺条件为:乙醇质量分数为90%,LREPS用量为2.0 g,一氯乙酸用量为3.0 g,氢氧化钠用量为4.0 g,醚化温度为40°C,反应时间为4 h。结论建立了CM-LREPS制备工艺并获取了相关抗肿瘤技术参数,为该多糖制剂的生产应用奠定了一定基础。

Objective To establish a preparation technology of carboxymethylated low molecular weight exopolysaccharide from Rhizobium sp. N613（CM-LREPS） and to explore its antitumor activity.Methods Low molecular weight exopolysaccharide from Rhizobium sp. N613（LREPS） was modified by ClCH2COOH using ethanol as the solvent.The reaction conditions were optimized by orthogonal test and a series of CM-LREPS were acquired.The molecular structure of the CM-LREPS was analyzed by fourier transform infrared spectra（IR）.Then the antitumor activities of four different degrees of substitution were evaluated in mice bearing hepatoma ascites H22.Results The IR results indicated that LREPS was carboxymethylated successfully.Antitumor test indicated that the inhibition rate reached 59.2% when the degree of substitution of CM-LREPS was 0.659.Using the degree of substitution and the inhibition rate as detection indicators,the optimum preparation conditions of CM-LREPS were as follows：the concentration of ethanol of 90%,2.0 g LREPS,3.0 g ClCH2COOH,4.0 g NaOH,the etherification temperature of 40°C and the reaction time of 4 h.Conclusion The technology of preparing CM-LREPS is successfully established.Moreover,the relevant technical parameters are obtained,which lay a certain foundation for the production and application of the polysaccharide.