Daviditin B from Swertia davidi Franch.

AimTo study the active constituents of Swertia davidi Franch. MethodsChemical components were isolated by column chromatography and their structures were established mainly by spectroscopic means (UV, IR, NMR, 2D-NMR, MS). ResultsThree substances were identified as 2,5-dimethoxyl-1,4-dicarboxyl benzene (VIII), 1,5,8-trihydroxyl-3,4-dimethoxyl xanthone (IX) and 1,8-dihydroxyl-3-(3′-hydroxyl-butoxy) xanthone (X). ConclusionCompounds VIII and IX were isolated from Swertia davidi Franch. for the first time, whereas compound X is a new xanthone, named daviditin B with antioxygenated activity in vitro.