An antiproliferative xanthone of Symphonia pauciflora from the Madagascar rainforest.

Investigation of a Malagasy endemic plant identified as Symphonia pauciflora Baker (Clusiaceae) for antiproliferative activities against the A2780 ovarian cancer cell line led to the isolation of a new compound identified as 2-(3,3-dimethylallyl)-7-methoxy-l,5,6-trihydroxy-2",2"-dimethylpyrano(6",5":3,4) xanthone (1) and the two known guttiferones A (2) and I (3). The structure elucidation of 1 was based on the analysis of its 1D and 2D NMR and mass spectral data. Compound 1 showed good antiproliferative activity with an IC50 value of 3.8 microM against the A2780 human ovarian cancer cell line, while the known guttiferone analogues (2 and 3) exhibited moderate activities with IC50 values of 8.3 microM and 7.8 microM, respectively.