Preparation Of Ginsenoside Rg3 By Biotransformation Ginsenoside Rb1 In Deep Eutectic Solvent

The preparation of ginsenoside by bio-enzyme conversion has the characteristics of high selectivity,strong specificity,high conversion rate of target product,mild reaction conditions and environmental friendliness.Generally,water is used as the reaction medium in biological enzyme conversion,but the three-dimensional structure of enzyme may not be fully developed due to the influence of water polarity.Thus,the conversion ability of biological enzymes is reduced.Deep eutectic solvents(DES)have the characteristics of low cost,simple preparation,high biodegradability,and can be used as an enzyme catalytic conversion medium for biological enzyme conversion.In this thesis,low-eutectic solvent is used as a new enzyme-catalyzed reaction medium to convert ginsenoside Rb1 and prepare rare ginsenoside Rg3.Drug analysis and pharmacological studies show that ginsenoside Rg3 has a significant anti-tumor effect and has a good inhibitory effect on cancer cells.A chromatographic method was established for the simultaneous determination of six ginsenosides.UG80-CAPCELL PAK SCX(I.D.4.6 mm×250 mm,5 μm)With the chromatographic column as the stationary phase,ginsenosides Rh2,C-K,Rg3,F2,Rd and Rb1 can be separated rapidly.The method has high accuracy and good reproducibility.The mixed phosphate buffer solution of choline chloride-urea-isopropyl alcohol eutectic solvent was used as the enzyme-catalyzed reaction medium for the enzyme-catalyzed conversion of ginsenoside Rb1.The effects of the optimum reaction temperature and pH value of the enzyme were investigated.At different pH values and temperatures,the products obtained by enzyme conversion are different,so the reaction path of enzyme conversion is different.The products of enzyme-catalyzed transformation were analyzed and identified by mass spectrometry to determine the types of products.The conversion of ginsenoside Rg3 can be obtained in the low eutectic solvent-phosphate system with a yield of 45.00%,and the reaction system has a higher reaction temperature tolerance(55 ℃).Artificial neural network was used to explore the radial diffusion in the preparative column,and BP network was used to predict the retention time corresponding to different flow rates under the preparative column.The structure of neural network is optimized,including the number of network layers,the number of neurons in each layer,the number of hidden layers,hidden layer neurons and neurons.The retention time at different flow rates in the semi-prepared column can be predicted by using artificial neural network.The network structure is 2-4-2,the momentum factor is 0.60,the learning rate is 0.55,and the average relative error of retention time prediction is 2.31%;The average relative standard deviation of linear velocity prediction is 0.44%.