Application Of Molecular Imprinting Technology In The Study Of Three Natural Active Components

Molecularly imprinted polymers are extensivly applied in the field of natural products due to their high specificity,simple preparation,and low cost.Three different types of molecularly imprinted polymer materials were synthesized and used for fruit juice debittering,enrichment of metabolites of crude extract of epimedium and simultaneous enrichment of multiple target compounds from complex system.This thesis aims to make in-depth research and exploration based on the application of complex sample processing by molecular imprinting technology.The main research contents are as follows:(1)Using limonin as template and modified silica nanoparticles as supporting materials,molecularly imprinted polymers(MIPs)were prepared as a specific sorbent to remove the limonin from the lemon juice for the first time by the surface imprinting technology.The polymers were characterized by scanning electron microscopy,transmission electron microscopy and Fourier transform infrared spectrometer spectra.And the polymerization conditions and adsorption performances of the resultant nanomaterials were further investigated in detail.Results showed that the MIPs have higher adsorption capacity(27.72 mg/g)compared with surface molecularly non-imprinted polymers(NIPs)(8.12 mg/g).The selectivity experiment indicated that the polymers had excellent selective recognition for limonin and the selectivity factors were calculated as 2.75 and 1.83 for nomilin and obakunone,respectively.The MIPs were successfully used as adsorbent for selectively removing limonin from lemon juice and the MIPs extracted almost all the limonin from lemon juice according to the HPLC results.(2)Using surface imprinting technology,efficient,sensitive bifunctional monomer magnetic molecularly imprinted polymers(MMIPs)were fabricated and successfully applied to concentrate the metabolites of Epimedium flavonoids in rat testis and bone through ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS)analysis.Chitosan is bio-compatible and non-toxic,and methacrylic acid provides multiple hydrogen bond donors.Using chitosan and methacrylic acid as co-functional monomers,MMIPs exhibited a large adsorption capacity(7.60 mg/g),fast kinetics(60 min),and good selectivity.Selectivity factors of MMIPs were 2.63 and 2.12 for luteolin and emodin,respectively.The MMIPs showed excellent linearity in the range of 5-150 ?g/mL;the low detection limits and low quantification limit were 0.025 and 0.05 ?g/mL,respectively.The MMIPs were injected into rat testis to specifically enrich the total flavonoid metabolites in vivo and were used to extract metabolites from bone in vitro.The results showed that the MMIPs coupled with UPLC-Q-TOF-MS successfully identified 30 compounds from testis and 19 compounds from bone,including 29 new compounds.This study provided a reliable protocol for the concentration of metabolites from complex biological samples,and several new metabolites of Epimedium flavonoids were found in vivo and in vitro.(3)Using quercetin and schisandrin b as double templates and deep eutectic solvents as functional monomers,double template molecular imprinted polymers(DMIPs)with biocompatibility were prepared by bulk polymerization.The results showed that DMIPs could rapidly reach the adsorption equilibrium at 80 min,and the maximum adsorption amounts of quercetin and schisandrin b were 23.58 mg/g and 41.64 mg/g,respectively.The selective experiments showed that DMIPs had a good ability to recognize quercetin and schisandrin b,and the selective factors of luteolin,icariin,schisandrin a and schisandrin were 1.71,1.83,3.95 and 2.17,respectively.The DMIPs were successfully utilized for enriching quercetin and schisandrin b from the crude of penthorum chinense and schisandra simultaneously.Furthermore,at different time points,quercetin and schisandrin b were successfully detected in blood samples of mice which fed with DMIPs contain quercetin and schisandrin b,and their pharmacokinetics were similar to the results reported in the literature.In this chapter,we demonstrate that molecularly imprinted materials can be used to specifically extracte target products from complex substrates,and molecularly imprinted polymers that contain target products can be further used in many other aspects.