目的:探讨硫酸化修饰柴胡多糖(BCP)的影响因素,阐明硫酸化柴胡多糖(S-BCP)抗氧化能力提升的可能机制.方法:利用氯磺酸-吡啶法对BCP进行了硫酸化修饰.通过调节氯磺酸与吡啶的体积比(1:2、1:4和1:8),观察S-BCP的取代度(DS);应用红外(IR)光谱初步分析BCP和S-BCP的结构,扫描电子显微镜(SEM)下观察分析BCP和S-BCP的表面形态表现.基于1,1-二苯基-2-三硝基苯肼(DPPH)自由基的清除能力建立抗氧化模型,实验分为阳性对照组、BCP组和S-BCP组,检测各组DPPH自由基的清除率.结果:当氯磺酸与吡啶的体积比为1:4、反应时间为2 h、反应温度为60℃时,制得S-BCP的含硫百分率最大值为18.62%,DS最大值为2.32.与BCP组比较,各剂量S-BCP组DPPH自由基的清除率升高(P<0.05).结论:氯磺酸与吡啶的体积比影响S-BCP的DS值,BCP经硫酸化修饰后通过改变多糖的理化性质和空间构象而提升其抗氧化能力.%Objective: To investigate the influencing factors of sulfated modification of Bupleurum chinense polysaccharides (BCP),and to elucidate the possible mechanism of improving the antioxidant ability of sulfated BCP (S-BCP).Methods:BCP was sulfated by chlorosulfonic acid-pyridine method.The degree of substitution (DS)of S-BCP was observed by adjusting the volume ratios of chlorosulfonic acid to pyridine (1:2,1:4,and 1:8).The structures of BCP and S-BCP were analyzed by infrared (IR)spectroscopy,the morphology of BCP and S-BCP were observed under scanning electron microscopy (SEM).The antioxidant model was established by using 1, 1-diphenyl-2-picrylhydrazyl (DPPH)free radical scavenging.The experiment was divided into positive control group,BCP group and S-BCP group,and the scavenging rates of DPPH free radical in various groups were compared. Results:When the volume ratio of chlorosulfonic acid to pyridine was 1 : 4,the reaction time was 2 h and the reaction temperature was 60 ℃,the maximum sulfur content percentage of S-BCP was 18.62% and the DS was the highest (DS = 2.32 ).Compared with BCP group, the scavenging rate of DPPH free radical of S-BCP was significantly increased (P <0.05).Conclusion:The volume ratio of chlorosulfonic acid to pyridine can affect the DS of S-BCP.The sulfated modification can increase the anti-oxidant capacity of BCP by changing its physic-chemical characters and spatial conformation.
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