title: Bioassay- and liquid chromatography/mass spectrometry-guided acetylcholinesterase inhibitors from Picriafel-terrae.
abstract: BACKGROUND
  Picria fel-terrae is a traditional Chinese medicine.
  
  
  METHODS
  A new approach to the search for acetylcholinesterase (AChE) inhibitors from Picria fel-terrae is presented.
  
  
  RESULTS
  Bioassay- and LC-MS-guided fractionation of the ethyl acetate extract was from traditional Chinese medicine P.fel-terrae. Following primary extraction, the ethyl acetate extracts fraction of P.fel-terrae showed strong AChE inhibitory activities. So the sample was separated using highperformance liquid chromatography (HPLC). The effluent was split towards two identical 96-well fraction collectors, and the presence of the biologically interesting portion and chromatographic fractions could be readily detected by analyzing selected ion chromatograms through an electrophoresis-electrospray ionization mass spectrometry (ESIMS) system for accurate mass measurement. One 96-well plate was used for a bioassay (AChE-inhibitory assay) and detected the bioactivity and position of the relevant peak in the chromatogram. The positive well in the second 96-well plate was used for identification by LC-(+) ESIMS.
  
  
  CONCLUSIONS
  As abovementioned, the AChE inhibitory constituents from P.fel-terrae by LC-bioassay-ESIMS were rapid identified. Liquid chromatography/ mass spectrometry (LC-MS) screening detected the presence of six active compounds, identified as picfeltarraenin IA (1), picfeltarraenin IB (2), picfeltarraenin IV (3), picfeltarraenin X (4), picfeltarraenin XI (5), and one unknown compound. The structures were further determined by 13C NMR. The six compounds expressed stronger AChE inhibition than the known AChE inhibitorTacrine. Above all, the value of this LC-bioassay-ESIMS methodology is highlighted by the finding and structure elucidation of the active constituents from many other structural families of natural products.
authors.affiliation: School of Pharmacy, Guangdong Pharmaceutical University, Institute of Materia Medica, Guangdong Pharmaceutical University, Guangzhou, P.R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wen
authors.forename: Qiqiu
authors.initials: Q
authors.lastname: Wei
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Fan
authors.initials: F
authors.lastname: Liu
authors.forename: Shichang
authors.initials: S
authors.lastname: Zhang
authors.forename: Tinghuo
authors.initials: T
authors.lastname: You
keywords: Acetylcholinesterase inhibitory activity; LC-bioassay-ESIMS; Picriafel-terrae