Preparation And Characterization Of Cellulose Sulfate And Starch Sulfate

Cellulose sulfate(NaCS)is a kind of cellulose derivative.It is made from natural cellulose by sulfonating.NaCS with high degree of substitution have the effect of contraception,antibiosis and antivirus,and can be used as contraceptive or antibacterial.It can be used as a spermicide using together with other medicaments.It nearly has no stimulation to versus vagina mucous membrane,and does not destroy salutary florae in vagina.It has the effects against some viral infect,such as HIV,HSV and so on.The antivirus action is related to both molecular weight and degree of substitution of NaCS.The NaCS with high molecular weight and degree of substitution have strong antivirus property. The preparation of NaCS has some difficulties,especially for the NaCS with high degree of substitution.Till now there is no report on the industrial preparation of NaCS,which certainly hampers the application of NaCS as the antibiosis or antivirus agents.Starch sulfate is one of the modified starches which have biological activities.It was reported that starch sulfate has also the activity of anti-HIV,anti-tumour and antivirus.Theerfore,it is important to study the preparation and biological activities of NaCS and starch sulfate with environmental-friendly and economic methods.With the mixture of concentrated sulfuric acid and n-propanol as the sulphonating agent, NaCS and starch sulfate with high degree of substitution were prepared.Several factors, such as the ratio of concentrated sulfuric acid to n-propanol,liquid-to-solid ratio of reactant/cellulose,reaction temperature and reaction time,were investigated systematically. The optimized preparation conditions of NaCS is as the ratio of concentrated sulfuric acid to n-propanol 1 at 2.1,the liquid-to-solid ratio of reactant/cellulose at 1:45,reaction temperature at 0℃,reaction time of 16 hours.The degree of substitution of NaCS can be controlled between 0.3-1.0 with the molecular weight at the range of 100-2000 kD.The optimized preparation conditions of starch sulfate is as the ratio of concentrated sulfuric acid to n-propanol at 1.8,the liquid-to-solid ratio of reactant/cellulose at 1:30,reaction temperature at -2℃,the reaction time of 15 hours,under continuous stirring during the reaction.The degree of substitution of starch sulfate can be controlled between 0.1-0.6.The biological activities of NaCS and starch sulphate were also investigated.It was found that the NaCS prepared do not impact the growth of E.coli and Lactobacilli.The preliminary study in the Academy of Military Medical Science indicated that NaCS showed some antivirus properties.The starch sulfate prepared showed strong inhibition of pepsin. The inhibition action of starch sulfate increased with the increase of concentration and degree of substitution.When the concentration of starch sulfate reaches 2%,80-90%activity of pepsin can be inhibited.When the degree of substitution is 0.4-0.5,90%activity of pepsin is inhibited.The results indicated that starch sulfate is a good inhibitor to pepsin,but more biological activities still need be exploited.