title: Preparative isolation and purification of four flavonoids from the petals of Nelumbo nucifera by high-speed counter-current chromatography.
abstract: BACKGROUND
  Flavonoids, the primary constituents of the petals of Nelumbo nucifera, are known to have antioxidant properties and antibacterial bioactivities. However, efficient methods for the preparative isolation and purification of flavonoids from this plant are not currently available.
  
  
  OBJECTIVE
  To develop an efficient method for the preparative isolation and purification of flavonoids from the petals of N. nucifera by high-speed counter-current chromatography (HSCCC).
  
  
  METHODS
  Following an initial clean-up step on a polyamide column, HSCCC was utilised to separate and purify flavonoids. Purities and identities of the isolated compounds were established by HPLC-PAD, ESI-MS, (1)H-NMR and (13)C-NMR.
  
  
  RESULTS
  The separation was performed using a two-phase solvent system composed of ethyl acetate-methanol-water-acetic acid (4 : 1 : 5 : 0.1, by volume), in which the upper phase was used as the stationary phase and the lower phase was used as the mobile phase at a flow-rate of 1.0 mL/min in the head-to-tail elution mode. Ultimately, 5.0 mg syringetin-3-O-beta-d-glucoside, 6.5 mg quercetin-3-O-beta-d-glucoside, 12.8 mg isorhamnetin-3-O-beta-d-glucoside and 32.5 mg kaempferol-3-O-beta-d-glucoside were obtained from 125 mg crude sample.
  
  
  CONCLUSIONS
  The combination of HSCCC with a polyamide column is an efficient method for the preparative separation and purification of flavonoids from the petals of N. nucifera.
authors.affiliation: College of Food Science and Engineering, Shandong Agricultural University, 61 Daizong Street, Taian, Shandong 271018, People's Republic of China.
authors.forename: Guo
authors.initials: G
authors.lastname: Xingfeng
authors.forename: Wang
authors.initials: W
authors.lastname: Daijie
authors.forename: Duan
authors.initials: D
authors.lastname: Wenjuan
authors.forename: Du
authors.initials: D
authors.lastname: Jinhua
authors.forename: Wang
authors.initials: W
authors.lastname: Xiao
mesh_terms: D003377:Countercurrent Distribution / Q000295:instrumentation / Q000379:methods*; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification*; D035264:Flowers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D031653:Nelumbo / Q000737:chemistry*; D009757:Nylons / Q000737:chemistry; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D005419:Flavonoids; D009757:Nylons