| Ginkgo leaves extract has a variety of pharmacological effects such as anti-oxidation,antagonizing platelet activating factor and protecting the central nervous system.Flavonoids and ginkgolides are important active ingredients in Ginkgo leaves.Improving the separation efficiency has great significance to the development of new drugs,quality control and comprehensive utilization of Ginkgo resources.Molecular imprinting technology provides a feasible solution for rapidly and effectively separating target compounds from natural products.In this paper,molecularly imprinted polymers(MIPs)with specific recognition ability for active ingredients,kaempferol and ginkgolides,were designed and prepared,and they were applied to directly separate and purify the target components from the extract of ginkgo leaves.The main research contents and results of this paper are as follows:(1)To prepare the kaemferol-MIPs,kaempferol was used as the template molecule,along with acrylamide(AM),α-methacrylic acid(MAA)and 4-vinylpyridine(4-vp)as the functional monomers,while ethylene glycol dimethacrylate(EDMA),divinylbenzene(DVB),glycerol dimethacrylate(GDMA)and trihydroxymethylpropane triacrylate(TMPTA)as the crosslinking agents.And the effects of the types of functional monomers and crosslinking agents on the adsorption capacity and specific recognition capacity of the prepared MIPs were studied by using adsorption amount q,partition coefficient Kp and imprinting factor I as evaluation indicators.The research results showed that 4-vp was performed outstanding adsorption capacity for kaempferol as a functional monomer,and EDMA and GDMA were the fine crosslinking agents for preparing MIPs.The MIPs prepared with 4-vp and EDMA had a porous structure and high specific surface area.Furthermore,it shows high affinity and specific recognition ability for kaempferol.Especially,in the low concentration area,its adsorption of kaempferol was mainly on the homogeneous imprinted pores,and the Langmuir model gave a well fit with the adsorption isotherm.The adsorption kinetic test results showed that the adsorption of kaempferol on MIPs was faster,and the adsorption process conformed to the quasi-second-order kinetic adsorption model.MIPs were used as solid-phase extraction adsorbents and had a high adsorption breakthrough point(9.0 BV).Using SPE method,MIPs could effectively separate quercetin and kaempferol from ginkgo leaves extract,the elution recovery rates were 65.18%and 48.19%,respectively.In the meantime,the removal rate of other substances was about 82-99%.The results showed that the MIPs SPE method could effectively separate and purify quercetin and kaempferol from ginkgo leaves.(2)Using self-made ginkgolide mixture as template molecule,acrylic acid(AA)as functional monomer,EDMA and GDMA as cross-linking agent,ginkgolide-MIPs were prepared with a fixed molar ratio of functional monomer to cross-linking agent at 1:5.Where the contents of GA and GB in the mixed lactone template were 59.7%and 39.1%,respectively.The effects of the types of crosslinking agents and the ratio of template to functional monomer on the adsorption capacity and specific recognition capacity of the prepared MIPs were studied.The results showed that,when the molar ratio of template:AA:GDMA was at 1:8:40,the prepared MIPs had a heterogeneous adsorption surface and adsorbed GA and GB with higher Kp and I values,which were significantly higher than flavonoids,indicating that the prepared MIPs had good specific recognition ability for terpene lactones.In this thesis,the molecularly imprinted systems for kaempferol and ginkgolides have been screened and the MIPs have been successfully prepared,which is of great significance for improving the separation efficiency of flavonoids and ginkgolides from ginkgo leaves.At the same time,it also has important guiding significance to promote the quality control of Ginkgo and improve the comprehensive utilization of Ginkgo resources. |
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