| Eucommia ulmoides is a unique economic plant in China.The leaves of Eucommia ulmoides are rich in chlorogenic acid.Chlorogenic acid is an important biological active substance with ant-iviral,anti-tumor,anti-microbico and other pharmacological effects,which is widely used in the treatment of diseases of blood,digestive and reproductive systems.The research and development of Eucommia ulmoides leaves are gradually expanding,and the extraction and content determination of its active components are the focus of research.The research on the extraction and purification process of chlorogenic acid in Eucommia ulmoides leaves is significant to the production,development and application of chlorogenic acid.In this study,chlorogenic acid was isolated and purified from Eucommia ulmoides leaves by macroporous adsorption resin.The adsorption mechanism was investigated via static and dynamic adsorption/desorption experiments,and the enrichment process was optimized.Specific research contents and conclusions are as follows:(1)Optimization of extraction process of chlorogenic acid from Eucommia ulmoides leaves.By orthogonal test,the effects of extraction method,ethanol concentration and solid-liquid ratio on the extraction efficiency of chlorogenic acid were firstly discussed,and then the effects of ethanol concentration,reflux time and solid-liquid ratio were also discussed.By means of static adsorption/desorption experiments,the best macroporous resin was selected,and its adsorption kinetics and thermodynamics were studied.The purification process was optimized via dynamic adsorption/desorption experiments.The results showed that the optimal extraction conditions for chlorogenic acid from Eucommia ulmoides leaves were as follows:Ethanol extraction technology,ethanol concentration of 30%,solid-liquid ratio of 1:20,reflux time of 180 min.Among the six macroporous resins studied,XDA-8 resin had the best adsorption performance,and the static adsorption data of chlorogenic acid on XDA-8 resin could be well fitted by pseudo-second-order kinetic model and Langmuir isotherm model.(2)Mechanism of adsorption of chlorogenic acid on macroporous resin.The molecular size of chlorogenic acid was optimized by Materials Studio software first,and the possible adsorption forms of chlorogenic acid on XDA-8 resin were calculated and simulated,and the adsorption mechanism was discussed.Results showed that the adsorption of chlorogenic acid on XDA-8 resin is mainly controlled by the chemical mechanism,due to the charge transfer happened between O atoms of chlorogenic acid molecule and pi electrons of resin skeleton polystyrene molecular,thus produce the electron cloud overlap,and more hydroxyl oxygen of chlorogenic acid molecular near the resin skeleton,the stronger adsorption capacity was.(3)Optimization of chlorogenic acid enrichment and purification process.The purification process of chlorogenic acid was optimized by dynamic adsorption/desorption experiments.The results showed that the optimized purification process conditions were as follows:loading concentration 5.71 mg/mL,loading volume 3BV flow rate of sample 2BV/h,eluent 4 BV 45%ethanol and 2BV 60%ethanol(v/v),flow rate of eluent 2BV/h.After one cycle treatment with XDA-8 resin column,the content of chlorogenic acid increased by 5.25 times and the recovery was 85.4%. |
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