Research On Natural Products Of Glycosides And Phenolic Acids In Three Resource Plants In Xinjiang

This work mainly researches the natural products from Stevia rebaudiana,Helianthus annuus L.,Orobanchaceae and their residues from industrial production in Xinjiang.To utilize the mother liquor of stevia,we used enzyme modification method to process it.For the waste of Stevia rebaudiana root,we used it as a material to product melanin.For sunflower shell and sunflower meal,we used them as the material of the fermentation culture medium to product melanin.We used CGTase to changing structure of phenylethanol glycosides contained in the plants of the Orobanchaceae.We expect these researches can provide experimental basis to th comprehensive utilization of Stevia rebaudiana,Helianthus annuus L.and Orobanchaceae.The relevant results are as follows.(1)The enzyme modification of stevia in mother liquor: we selected a strain producing glycosyltransferase,and the conversion result of this strain was compared with commercial enzyme—CGTase.Comparing the extraction of enzyme of this strain with commercial CGTase,the result of enzyme modification experiments showed that the conversion rate of the selected bacteria CGT7 was 45.5% and the conversion rate of commercial CGTase was 64.4% under the primary experimental condition.After optimization,the optimum conversion conditions of CGTase were set to: p H 5.5,70?,the addition of stevioside 100g/L,the conversion time is 6 hours,under which the conversion rate could reach 79.2%.The experiment of immobilized CGTase showed that the conversion rate of using immobilized enzyme was 59.2%,which was lower than free CGTase.If the immobilized CGTase was reused,the conversion rate decreased by 15.8%,and the retention rate of enzyme activity was 84.1%.The HPLC analysis of enzyme modified products of stevioside revealed that 3 new response peaks of new products appeared after conversion.Combined with LCMS analysis,it was determined that 3 new products were all STV transglycosylic products: STV+1Glc,STV +2Glc and STV+3Glc,which account for 34.2%,26.4% and 21.5% respectively.In addition,a little RA transglycosylic products RA+1Glc and RA+2Glc etc were formed after conversion,which only account for 10.2% and 7.7%.The conversion rates of STV and RA were 83.0% and 65.9% respectively.(2)The optimization of enzyme modified: This work used gelatinized soluble starch instead of dextrin as a new glycosyl donor,which greatly reduced the cost of supplementary materials.The starch can be well-distributed in the reaction liquid after gelatinization,which overcomes the disadvantages of low solubility of starch and easy aggregation and precipitation,improves conversion efficiency,and reduces the amount of remaining raw materials in the product.The amount of remaining STV fell from 2.61% to 2.21% after optimization.The simple and cheap ethanol precipitation method was used to remove the dextrin or starch,so as to achieve the requirement of optical rotation standard.Compared with the usual resin adsorption method to remove dextrin or starch whose conventional treatment process need dozens of hours,ethanol precipitation method can reduced process time to 4-5 hours,which greatly improves the separation efficiency.Ethanol can be effectively recovered and recycled through distillation.The experiment shows that the optical rotation value can be effectively reduced from 102.6 to 71.2(reach the standard)after adding ethanol(4 times the volume of the reaction liquid)and separating the precipitate,which provides a quick and effective method for improving the quality of enzyme modified stevioside product.The precipitated dextrin or starch can be recycled.(3)Utilization of Stevia rebaudiana root,sunflower meal and sunflower shell: Fermentation of sunflower shell by Neurospora and Trichoderma(both are rich of cellulase)can dissolve part of the melanin and nutrients in sunflower shell.Using mix of sunflower shell and sunflower meal can increase the breathability of medium.When the melanin of sunflower meal or sunflower shell was extracted separately,the melanin yields are 18.6% and 19.4% respectively.After the fermentation of by optimization culture medium which contained mixure of sunflower meal and sunflower shell in 3:1,the output melanin has increased by 24.8% comparing to the none-fermentation and the melanin yields are 18.2%,which shows no marked decrease.(4)Glycosyltransferase using to change structure of phenylethanol glycosides: After treatment by CGTase,acteoside in Orobanchaceae can be converted to echinacoside(the content of echinacoside increased from 0.58% to 0.91%,which has an increase rate of 56.6%).Enzyme modification treatment can raise the available value of cheap Orobanchaceae.The phenethylethanol glycosides in cheap Orobanchaceae can be converted to echinacoside that exists in Cistanche deserticola,which can help reduce the ecological damage caused by excavating Cistanche deserticola and relieve the current situation that Cistanche resources are defficiency.It has important ecological and economic value.Compared with the chemical synthesis method,the biotransformation method has some advantages—fewer steps,simple process,convenient operation,environmental friendliness and low energy consumption.