| Ginkgo biloba L.It is a ginkgo plant of ginkgo family,which is of great economic value and rich in germplasm resources in the whole country.According to the present situation of development in China,the resource development products of ginkgo biloba are mostly concentrated in the trunk,branches,leaves and fruits of ginkgo biloba.However,with the production of ginkgo fruit every year,a large number of ginkgo pericarp is mostly treated with waste.In recent years,with the deepening of ginkgo research,the utilization value of ginkgo pericarp has been re-valued.Among them,ginkgolic acid is an active component which mainly exists in the outer seed coat,which can play an anti-tumor,antibacterial,anti-obesity and other functions.However,at present,the research and utilization of ginkgo biloba pericarp is less,and because the price of ginkgo phenolic acid is expensive,we can improve its extraction and enrichment process,so as to obtain a better economic prospect.In this paper,the extraction method of ginkgolic acid was systematically studied by using the high recognition characteristics of molecular imprinting technology.Firstly,the experimental scheme was selected,that is,the imprinted polymer was prepared by using salicylic acid as false template.Select the target molecule,ginkgolic acid,The adsorption properties of ginkgolic acid by polymer were determined.Subsequently,the adsorption and desorption properties of the polymer were optimized to prepare imprinted polymers with high adsorption properties for ginkgolic acid.It provides a new and effective method for the enrichment and extraction of ginkgo phenolic acid.The main research contents are as follows(1)The content of ginkgolic acid in ginkgo biloba exocarp was determined.Using ginkgo biloba exocarp as raw material,the determination scheme based on HPLC was established to determine the content of ginkgolic acid.The results showed that the content of ginkgolic acid was between 4% and 5%.(2)Optimization of Ginkgo biloba phenolic acid extraction: using ginkgo biloba pericarp as raw material,the extraction effects of phenolic acid were investigated by three extraction methods: extraction,reflux extraction and ultrasound-assisted extraction.The effects of solvent type,time and liquid-material ratio on the extraction rate were discussed.Finally,the optimum extraction conditions of ginkgolic acid were obtained.The extraction conditions were as follows: using ultrasonic-assisted extraction method,petroleum ether was used as extraction solvent,the ratio of liquid to material was 6 to 1,and the time was 3 hours.(3)Optimization of polymer synthesis: in this paper,the effects of the amount of target molecules,functional monomers and cross-linking agents on the adsorption properties of synthetic polymers were investigated,and the optimum synthesis steps were obtained,that is,4-vinylpyridine was used as functional monomer.The ratio of target molecule,functional monomer and cross-linking agent is 1 to 4 to 10,and the solvent is 90% methanol solution.(4)Study on the adsorption mechanism of polymer.Salicylic acid was used as the template molecule and 4-vinylpyridine was used as the functional monomer to form a certain ionic bond structure.Then,with the addition of cross-linking agent,the imprinted polymer with high adsorption to 4-hydroxybenzoic acid was synthesized under the action of catalyst.Then,the imprinting mechanism of the synthesized polymer was analyzed by nuclear magnetic resonance spectroscopy and infrared spectroscopy,and then the structure of the polymer was characterized by scanning electron microscope(SEM).In the aspect of investigating the adsorption capacity of polymer,the content analysis methods such as HPLC and UV detection were used to detect the adsorption capacity of polymer.The results show that MIP not only has a good spatial structure but also has a strong adsorption performance.The adsorption rate reached 95.9%,and the mechanism analyzed by Scatchard mathematical model showed that there were two different binding sites in the adsorption process,in which(Qmax1)= 30 mg/g;(Qmax2)= 80 mg/g,adsorption kinetics was quasi-second-order kinetics.(5)Study on adsorption and desorption properties of polymers;in the adsorption process of polymer,different solvents have great influence on the adsorption effect of polymer.In this paper,the adsorption properties of molecularly imprinted polymer(MIP)for ginkgolic acid in Ginkgo biloba exocarp extract under different solvents were investigated.At the same time,on the basis of the above,the effects of different adsorption time,temperature and addition amount on the adsorption effect of polymer(MIP)were studied.the optimum adsorption conditions were obtained,that is,at the temperature of 40 ℃.Polymer added to 37.74 mg,Adsorption for 4 hours,at this time the Q=108.64mg/g.Desorption solvent and desorption agent to find the optimal adsorption conditions,the results show that ultrasonic desorption is the best in 10% acetic acid petroleum ether solution. |
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