Cytotoxic prenylated xanthones,and the unusual compounds anthraquinobenzophenones from Cratoxylum sumatranum

Six new xanthones, cratoxyarborenones A-F (1-6), were isolated from the leaves, twigs, and/or stem bark of Cratoxylum. sumatranum, along with the known compound, vismione B (9), as active constituents by bioassay-directed fractionation using the KB human cancer cell line cytotoxicity assay. In addition, two novel anthraquinobenzophenones, cratoxyarborequinones A (7) and B (8), and two known compounds, 2,4,6-trihydroxybenzophenone 4-O-geranyl ether and delta-tocotrienol, were obtained as inactive constituents.