OBJECTIVETo study the chemical constituents in roots of P. fallax and their anti-oxidation activities in vitro.

METHODColumn chromatographic techniques were employed for isolation and purification of chemical constituents of the plant. The structures were elucidated on the basis of the spectral evidence and the physical and chemical character. The isolated compounds were screened with four anti-oxidation models in vitro.

RESULTSeven xanthones, 1,7-dihydroxy-2,3-methylenedioxyxanthone (1), 1-methoxy-2,3-methylenedioxyxanthone (2), 3-hydroxy-1,2-dimethoxyxanthone (3), 1,6,7-trihydroxy-2,3-dimethoxyxanthone (4), 7-hydroxy-1-methoxy-2,3-methylenedioxyxanthone (5), 1,3-dihydroxy-2-methoxyxanthone (6) and 1,3,7-trihydroxy-2-methoxyxanthone (7), were isolated from the roots of P. fallax. And compounds 1 - 7 showed different anti-oxidation activities in the different pharmacological models.

CONCLUSIONCompounds 2, 3, 5 and 7 were isolated from this plant for the first time. Xanthones from this plant showed anti-oxidation activities. The pharmacological activities of the pure compounds from this plant were also reported for the first time.