Isolation and structure determination of cypritibetquinone A and B, two new phenanthraquinones from Cypripedium tibeticum

AimTo 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. ResultsCypritibetquinones 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-1,4-phenanthraquinone (2), respectively, by extensive spectral analyses. ConclusionCypritibetquinones A and B are two new phenanthraquinones.