Separation And Enrichment Of Monoterpenoids From Sibiraea Angustat Extract With Magnetic Surface Dummy Template Molecularly Imprinted Polymers

Sibiraea angustata is the common herb in Tibetan folk.Modern pharmacological studies have shown that the it has many functions such as lowering blood lipids,lowering blood sugar,anti-oxidation,anti-tumor,regulating the immune system and anti-liver damage.Sibiraea angustata terpenoids are the main active ingredients for lipid-lowering effects.Based on surface molecular imprinting technology and dummy template molecules,this study successfully prepared a magnetic surface functionalized dummy template molecularly imprinted polymers with a core-shell structure,and performed a series of structural characterization and related adsorption experiments.The target compounds were successfully separated and enriched from the crude extracts from Sibiraea angustata.The main research contents and conclusions are as follows:（1）Isolation and identification of Sibiskoside:Continuous hot reflux ethanol solution extraction,system solvent separation,normal phase silica gel column chromatography,ODS reversed-phase column chromatography and preparative liquid chromatography were used,as well as nuclear magnetic and mass spectrometric techniques,1.1 g Sibiskoside was obtained and identified from the 95%crude ethanol extraction from the aerial part of the Sibiraea angustata,and the purity was 92.21%.（2）Preparation of magnetic surface functionalized dummy template molecularly imprinted polymers（DMIPs）:Magnetic Fe₃O₄nanoparticles were synthesized by hydrothermal method,and superparamagnetic Fe₃O₄@Si O₂@C=C microspheres were synthesized after further graft modification.DMIPs were synthesized in acetonitrile solution with Fe₃O₄@Si O₂@C=C as the carrier,geniposide as the dummy template molecule,4-VP as the functional monomer,EGDMA as the cross-linker,AIBN as the initiator.（3）Structural characterization of polymer materials:SEM,FT-IR,contact angle,TGA,VSM,and XRD were used on magnetic nanomaterials and imprinted materials as a series of characterization tests to analyze the surface morphology,particle size,functional group structure,hydrophilicity,thermal stability,magnetic saturation strength and crystal stability of the polymer materials.It proved that the Fe₃O₄nanoparticles,Fe₃O₄@Si O₂microspheres,Fe₃O₄@Si O₂@C=C microspheres,DMIPs and DNIPs were successfully prepared during the polymerization process.And they all have good size,regular spheres,and superparamagnetism.The thermal stability of the imprinted materials is good,and DMIPs also showed good crystal stability.（4）Optimization of extraction conditions during the imprinting process:The extraction conditions of the magnetic surface functionalized DMIPs were optimized during the imprinting adsorption process,including temperature,p H and solvent environment.The experiment results showed that when the temperature is 35℃,the p H is weakly alkaline,and the solvent is methanol,DMIPs have the best adsorption effect on the target compound Sibiskoside.（5）Adsorption performance experiments and mechanism studies:The results of adsorption kinetics experiments and model studies showed that imprinted adsorption materials could reach adsorption equilibrium in about 40 minutes.Compared with DNIPs,DMIPs had faster adsorption speedadsorb on the target compound Sibiskoside.The second-order kinetic model had a higher fitting correlation coefficient for the adsorption process of imprinted materials,so it dominated the adsorption process.Isothermal adsorption experiments and model studies showed that the maximum adsorption capacity of Sibiskoside by DMIPs can reach 14.67 mg/g.The fitting results of the Freundlich model were closer to the adsorption process of imprinted materials,indicating that the adsorption process was easier to perform,and the adsorption process of the imprinted adsorption materials were mainly uneven in surface and multi-layer adsorption.Selective adsorption experiments showed that compared with the competing compounds as andrographolide,polydatin,arbutin,caffeic acid,neohesperidin dihydrochalcone and quercetin,DMIPs had the highest imprinting factors and reached 2.08.The selective separation coefficients were 1.73,1.23,1.50,1.49,3.73,and 8.91,indicating that DMIPs had a better selective recognition ability for Sibiskoside.It also had better recyclability.In practical applications,the adsorption of Sibiskoside by DMIPs was higher than other components in the crude extract of Sibiraea angustata.The purity of Sibiskoside could reach 78%,so it could be used for the separation and purification of monoterpenoids from the Sibiraea angustata.