title: Isolation and structure determination of cypritibetquinone A and B, two new phenanthraquinones from Cypripedium tibeticum.
abstract: OBJECTIVE
  To study the chemical constituents of Cypripedium tibeticum.
  
  
  METHODS
  Compounds were isolated by repeated silica gel chromatography and purified on Sephadex LH-20 and structures were determined by spectral analysis.
  
  
  RESULTS
  Cypritibetquinones A and B were isolated from the ethyl acetate residue and their structures were determined as 7-hydroxy-2-methoxy-1 4-phenanthraquinone (1) and 7-hydroxy-2, 10-dimethoxy-l1 4-phenanthraquinone (2), respectively, by extensive spectral analyses.
  
  
  CONCLUSIONS
  Cypritibetquinones A and B are two new phenanthraquinones.
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100094, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Liu
authors.forename: Jian-hua
authors.initials: JH
authors.lastname: Ju
authors.forename: Zhong-jie
authors.initials: ZJ
authors.lastname: Zou
authors.forename: Geng
authors.initials: G
authors.lastname: Lin
authors.forename: Jun-shan
authors.initials: JS
authors.lastname: Yang
mesh_terms: D000880:Anthraquinones / Q000737:chemistry / Q000302:isolation & purification*; D008968:Molecular Conformation; D015394:Molecular Structure; D029595:Orchidaceae / Q000737:chemistry*; D010616:Phenanthrenes / Q000737:chemistry / Q000302:isolation & purification*; D010946:Plants, Medicinal / Q000737:chemistry*; D027343:Rhizome / Q000737:chemistry
chemical_list: D000880:Anthraquinones; D010616:Phenanthrenes; C511325:cypritibetquinone A; C511326:cypritibetquinone B