title: [Determination of rhynchophylline and isorhynchophylline in Uncaria rhynchophylla by HPLC].
abstract: OBJECTIVE
  To explore an HPLC method for determination of rhnchophylline and isorhnchophylline in Uncaria rhnchophylla.
  
  
  METHODS
  An HPLC method has been developed for determination of rhnchophylline and isorhnchophylline. The transformation of rhnchophylline and isorhnchophylline after heating was also studied by HPLC-ESI-MS.
  
  
  RESULTS
  Good linearities of rhynchophylline and isorhynchophylline were 0.064-5.100, 0.064-5.110 mg, respectively. The average recoveries were from 87.51% to 88.83% for rhynchophylline and from 107.9% to 113.9% for isorhynchophylline. The recoveries of rhynchophylline and isorhnchophylline reference solutions after extraction were 12.60% and 40.00% in the reflux extraction procedure, respectively. While in the ultrasonic extraction procedure, the average recoveries of rhynchophylline and isorhynchophylline was from 99.48% to 103.2% and from 97.00% to 99.59%, resepectively. The recoveries of rhynchophylline and isorhnchophylline reference solutions after extraction were 47.08% and 51.03%, respectively. The unqualified recovery could be elucidated by HPLC-ESI-MS analysis, indicating that trhynchophylline could be transformed mostly into isorhynchophylline and a little amount of unkown composition, while isorhynchophylline could be transformed into rhynchophylline isocorynoxeine, corynoxeine and 22-O-beta-D-glucopyranosyl isocorynoxeinic acid during the extraction procedure.
  
  
  CONCLUSIONS
  Ultrasonic extraction procedure was more sutble for HPLC determination of the content of rhynchophylline and isorhynchophylline in U. rhnchophylla, however, the recovery problems should be paid attention to when it comes to the determination.
authors.affiliation: Engineering Research Center of Modern Preparation Technology of Traditional Chinese Medicine, Ministry of Education, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China. yangxiujuants@163.com
authors.forename: Xiu-Juan
authors.initials: XJ
authors.lastname: Yang
authors.forename: Yan-Long
authors.initials: YL
authors.lastname: Hong
authors.forename: Fei
authors.initials: F
authors.lastname: Wu
authors.forename: Ke-Feng
authors.initials: KF
authors.lastname: Ruan
authors.forename: Yi
authors.initials: Y
authors.lastname: Feng
mesh_terms: D002851:Chromatography, High Pressure Liquid; D026121:Indole Alkaloids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D000078183:Oxindoles; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization; D014465:Ultrasonics; D032070:Uncaria / Q000737:chemistry*
chemical_list: D026121:Indole Alkaloids; D000078183:Oxindoles; C052714:rhyncophylline