Study On The Technology Of Extraction And Separation Of Flavonoids And Polysaccharides From Ginkgo Biloba Leaves

Ginkgo biloba leaves is a large potential resources that reserves largely and has broad prospects, including mainly flavonoids, terpene, polysaccharides, alkaloids, phenols, amino acids, trace elements and other multiple active ingredients. The output of Ginkgo biloba leaves in China is 70% of world output, this thesis focused on the comprehensive use of active components from Ginkgo biloba leaves. In this thesis, the research work focused on the following three aspects: (1) optimizing the extraction techniques of flavonoids from Ginkgo biloba leaves by enzymatic hydrolysis; (2) extracting polysaccharides from Ginkgo biloba leaves and isolating by ultrafiltration; (3) extracting parameters of flavonoids from Ginkgo biloba leaves by supercritical carbon dioxide. The main research findings are as follows:1. The hydrolysis pretreatment with enzymatic before extraction with ethanol is helpful to get rid of cell wall of Ginkgo biloba, the yield of flavonoids from Ginkgo biloba can be raised. At the base of single factor experiments, the effect of the concentration of enzyme, pH value, temperature and time of enzymatic hydrolysis on the yield of the extraction of total flavonoids from Ginkgo biloba leaves was studied by response surface methodology (RSM). The results indicated that cellulase showed the better ability of enzymatic hydrolysis. The optimum conditions of enzymatic hydrolysis were: 100U/ml concentration, 116mins time, 40℃temperature and 4.5 pH value, the highest yield of total flavonoids was 2.63%. Comparing with single extraction with alcohol, the yield of total flavonoids was increased by 30%.2. The yield of polysaccharides from Ginkgo biloba leaves was increased by optimizing water extraction technology through orthogonal test. The ultrafiltration technology was introduced into the concentration and separation of polysaccharides from Ginkgo biloba leaves, which can be used to get rid of the impurities. At the base of single factor experiment, the effect of ratio of material water, time of extraction, temperature of extraction and times of extraction on the yield of the extraction of polysaccharides from Ginkgo biloba leaves was studied by orthogonal test. The result indicated that the optimal technical conditions of extraction were ratio of material water 1:30, time of extraction 3.5h, temperature of extraction 85℃and times of extraction 2 times, the highest yield of polysaccharides was 5.98%. It was judged roughly by ultrafiltration that molecular mass distribution of polysaccharides from Ginkgo biloba leaves contain two parts, one more than 100Kd and the other between 30 and 100Kd. The ultrafiltration technology of polysaccharides from Ginkgo biloba leaves was established primarily, which were molecular weight cut-off (MWCO) of membrane 30Kd, pressure 0.050MPa and temperature 30℃.The highest retention rate of polysaccharides was 90%; meanwhile the average membrane flux was 0.980 L/(min·m2).The optimal technology of extraction and ultrafiltration that operates steadily is viable and effective.3. Supercritical carbon dioxide extraction technique was used in the flavonoids from Ginkgo biloba leaves, which achieve to integrate with the extraction and separation processes. Supercritical carbon dioxide extraction that operates easily is of higher efficiency and lower energy consumption. At the base of single factor experiment, the yield of the extraction of flavonoids from Ginkgo biloba leaves was studied. The result indicated that the optimal technical conditions of supercritical carbon dioxide extraction were velocity of CO₂ 20L/h, concentration of alcohol 80%, time 2h, temperature 45℃and pressure 30MPa. The highest yield of flavonoids was 1.30%.