Study On Extraction And Purification Of Ginkgo Flavonoids From Ginkgo Biloba Leaves

Ginkgo resources is very abundant in China,which is the biggest producing area of Ginkgo biloba in the world.The Ginkgo flavonoids in Ginkgo biloba leaves have a series of effects such as anti-aging,prevention of blood vessel blockage,and lowering blood pressure.Thus they were widely used in some fields such as medicines and healthy products.At present,the market products are mainly Ginkgo biloba extract with a content of 24%flavonoids.The market competition is fierce.In order to increase the added value of products and move toward the high-end market,it requires constant improvement of extracts content of Ginkgo biloba flavonoids.This thesis researched methods to extract flavonoids from Ginkgo biloba leaves with higher content.1)Two methods of spectrophotometry and high performance liquid chromatography were established to determine the content of Ginkgo flavonoids in the extract.Single factor experiments were used to analyze the factors affecting the extraction process.The effects of heat reflux extraction,ultrasound-assisted extraction and water extraction processes on the extraction yield were investigated.The optimum process parameters for the extraction process were obtained by orthogonal experiments:the temperature is 70?,ethanol concentration is 70%,solid-liquid ratio is 1:15,extraction time is 30 min,water ratio is 1:5.The maximum extraction yield is 95.3%.After the elutriation,the flavonoids content and yield is 4.5%and 92.7%respectively..2)The purification process of AB-8 macroporous resin and polyamide resin was studied in this paper.The adsorption characteristics of the resin were investigated by static experiments.The adsorption kinetic curve and adsorption isotherm were drawn,and the gradient elution test of the resin was performed.The process parameters of the purification process were determined,and the effects of sample concentration and sample flow rate were examined.The permeation curves and desorption curves were plotted.The optimum process parameters for the macroporous resin are:Ginkgo biloba flavonoid extract solution is loaded on the AB-8 macroporous resin column and eluted firstly with 20%ethanol and then with 80%ethanol.The content and yield of the Ginkgo flavonoids extract was 35.1%and 82.7%respectively.The optimum process parameters of the polyamide resin are as follows:the ginkgo flavonoid extract is loaded on the polyamide resin column and eluted firstly with 10%ethanol and then with 60%ethanol.The content and yield of the Ginkgo flavonoids extract is 56.8%and 79.7%respectively.3)This paper studied the purification of Ginkgo flavonoids with macroporous resin and polyamide resin.The effect of the resin combination sequence on the product was investigated.The optimum process parameters were determined using orthogonal experiments,and the stability of the resin was tested.The optimal process parameters for the combination of resin are as follows:ethanol solution is used as the eluent and eluted firstly with two gradients of AB-8 resin.The eluent concentration of the first elution is 15%and the second elution is 70%.Secondly the polyamide resin is eluted by two gradient elution after loading,the eluent concentration of the first elution is 10%,the concentration of the second elution is 60%,and the content and yield of Ginkgo flavonoids is 73.6%and 64.0%respectively.