Optimization Of Extraction And Purification Technology,Physicochemical Characteristic And In Vitro Antioxidant Activity Of Polysaccharides From Tulipa Edulis Bulbus

Tulipa edulis(Miq.)Baker is a perennial herb belonging to the Tulipa genus in Liliaceae family.Its dry bulb without the tomentum,well known as Tulipa edulis bulbus in Chinese folk medicine,has long been used as a remedy to treat lymphoma,throat cancer,breast cancer,et al.Because of its outstanding clinical efficacy,the demand of T.edulis has been increasing fastly recently.Regrettably,the bioactive ingredient of T.edulis is unclear,and there is few research on its chemical components and pharmacological activity.As one of the main ingredients in T.edulis,the content of polysaccharide is high.Hence,exploring the optimal extraction and purification technology,physicochemical and biological activity of polysaccharide from T.edulis are of great significance for quality evaluation and effective use of T,edulis.The present thesis studied the optimum technology of extraction and purification,and the physicochemical and in vitro antioxidant activity of polysaccharide from T.edulis.Our conclusions were listed as follows:Based on single factor and Box-Behnken core combination design,the effects of extraction temperature,solid-liquid ratio and extraction time on the extraction rate of polysaccharides were investigated.Results showed that the influencing factors for extraction rate were in the order of ultrasonic time>extraction temperature>solid-liquid ratio.Optimum extraction parameters of polysaccharide from T.edulis were 70℃ for extraction temperature,30:1(mL/g)for solid-liquid ratio,170 min for ultrasonic time.Under these conditions,the predictive value of polysaccharides yield was 13.93%.We explored and established a set of simple purification technology for preliminarily purifying TEP as follows:the TEP after water extract and alcohol precipitation incubted with amylase to remove starch,incubted with 4%TCA for deproteinization,removed pigment by HPD-100 macroporous resin,and desalted by dialysis,etc..Based on color reaction of Molish reagent and iodine-potassium iodide,the results showed there were no starch,protein and other impurities left in TEP after preliminary purification.Physicochemical results showed that TEP1 was charactered by white powder or flocculent,tasteless,hygroscopicity and transparent solution.The pH value of 1%polysaccharide aqueous solution is 5.05.It is soluble in water,dilute acid,dilute alkali and dilute salt solutions,while hardly soluble in high concentration of ethanol,methanol,acetone and other organic solvents.Component testing results showed that the TEP1 contained not only the neutral polysaccharide,but also acidic polysaccharides and tiny amount of glycoprotein.The content of sugar,uronic acid,and protein were 43.14%,29.75%and 0.27%,respectively.The results of IR spectrum showed that the typical polysaccharide characteristic absorption of TEP 1 was in 4000 cm-1～500 cm-1,where existed uronic acid structure features.After identification,the sugar chain configuration was considered as pyranose.The scavenging effects for DPPH · radical and ROS free radical(includes O2-·radical and-OH radical)and the scavenging metal ion capacity for the total reducing power and metal ion chelating ability were investigated to evaluate the in vitro antioxidant activity using Vc as positive control group.The results showed that TEP1 in T.edulis possessed certain antioxidation activity,and the antioxidant activity varied with different test systems.Its scavenging effect on · OH radical is significantly higher than the control,Vc,within a certain concentration range.TEP1 also showed a strong chelating ability for metal ions,and the chelating ability significantly enhanced with the increase of concentration.However,the total reducing power of TEP 1 and the scavenging effect on DPPH and O2-·was weak.