title: Extraction, Preconcentration and Isolation of Flavonoids from Apocynum venetum L. Leaves Using Ionic Liquid-Based Ultrasonic-Assisted Extraction Coupled with an Aqueous Biphasic System.
abstract: BACKGROUND
  Ionic liquids (ILs) are considered as green solvents, and widely applied for the extraction of various compounds.
  
  
  METHODS
  The present research focuses on the extraction of flavonoids from Apocynum venetum L. leaves by ultrasound-assisted extraction (UAE). Several major influencing factors were optimized. Then, an aqueous biphasic system (ABS) was applied for further isolation of flavonoids.
  
  
  RESULTS
  The flavonoids were mainly distributed in the top phase, while impurities were extracted to the bottom phase. The parameters influencing the extraction, namely type and concentration of salt, temperature, and pH, were studied in detail. Under optimized conditions (72.43% IL extract, 28.57% (NH4)2SO4, 25 °C temperature, pH 4.5), the preconcentration factor and extraction efficiency were found to be 3.78% and 93.35%, respectively.
  
  
  CONCLUSIONS
  This simple and efficient methodology is expected to see great use in the extraction and isolation of pharmaceutically active components from medicinal plant resources.
authors.affiliation: Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China. tanzhijian@caas.cn.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Tan
authors.affiliation: Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China. ibfcyyj@163.com.
authors.forename: Yongjian
authors.initials: Y
authors.lastname: Yi
authors.affiliation: Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China. Cswhy328@126.com.
authors.forename: Hongying
authors.initials: H
authors.lastname: Wang
authors.affiliation: Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China. aruofly@126.com.
authors.forename: Wanlai
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China. ibfcwcy@139.com.
authors.forename: Chaoyun
authors.initials: C
authors.lastname: Wang
mesh_terms: D030010:Apocynum / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005419:Flavonoids / Q000302:isolation & purification*; D052578:Ionic Liquids; D010936:Plant Extracts / Q000302:isolation & purification; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D012997:Solvents; D014465:Ultrasonics; D014867:Water
chemical_list: D005419:Flavonoids; D052578:Ionic Liquids; D010936:Plant Extracts; D012997:Solvents; D014867:Water
keywords: aqueous biphasic system; flavonoids; ionic liquids; isolation; ultrasonic-assisted extraction