Study On Enrichment And Purification Of Ginkgo Flavonoids By Surfactant-assisted Foam Fractionation

A surfactant-assisted foam fractionation technology was developed to separate ginkgo flavonoids(GF) from Ginkgo biloba leaves by using a surfactant which can simultaneously achieve the dual roles of solubilizer and collector, then the GF were purified by macroporous resin adsorption technology.The results showed that sodium dodecyl sulfate(SDS) was the optimal surfactant for solubilizing GF. The solubilization mechanism of GF by SDS was mainly attributed to electrostatic attraction and hydrogen bonds. Appropriately increasing SDS concentration, solid-liquid ratio, leaching temperature, leaching time was beneficial for the solubilization of GF. The maximum concentration of GF of 1.13 mg/mL was achieved under the optimum leaching conditions using response surface methodology, and the optimal conditions were the SDS concentration of 1.15%(w/w), the leaching temperature of 68.6℃ and the leaching time of 3.5 h.The spherical tower could effectively increase the enrichment ratio at elevated temperature(50℃). A two-stage foam fractionation technology was developed for achieving a whole circulation. Furthermore, both the enrichment ratio and the recovery percentage of GF were improved and they were 5.82 and 76.25%, respectively under the optimal conditions: The first stage used the spherical column and its conditions were the temperature of 50℃, the volumetric gas velocity of 30 mL/min and the liquid loading volume of 80 mL. The second stage used the cylindrical column and its conditions were the temperature of 50℃, the volumetric gas velocity of 45 mL/min and the liquid loading volume of 80 mL.Macroporous adsorption resin was used to separate and purify GF from the foamate. The results of static adsorption/desorption experiments indicated that S-8 resin could be used as the optimal adsorbent among the five tested resins. The dynamic breakthrough curves, the concentration of desorption solvent and the dynamic desorption curves were investigated and the optimal dynamic adsorption/desorption conditions of S-8 resin on GF were determined as follows: the breakthrough volume was 65 mL when loading flow rate was 3.0 BV/h, and the consumption volume of desorption solvent was 40 mL when the desorption flow rate was 1.8 BV/h by using 75% ethanol solution as desorption solvent. Under the optimal conditions, the purity of GF in the eluent reached 27.5%, in which SDS was also removed. Additionally, HPLC-MS/MS result suggested that GF in the eluent mainly consisted of seven components. S-8 resin could be reused to purify GF five times before the regeneration.An integral process was designed for effectively separating and purifying GF from Ginkgo biloba leaves by using surfactant-assisted foam fractionation and macroporous resin adsorption. This work will be expected to provide some new insights into foam fractionation and macroporous resin adsorption for recovering some valuable non-surface-active materials from other plants and removing the undesirable materials in the foamate.