Two new xanthones from the roots of Cratoxylum cochinchinense and their cytotoxicity.

Two new xanthones namely cratochinone A (1) and cratochinone B (2), along with 16 known xanthones, were isolated from the roots of Cratoxylum cochinchinense. Their structures were characterized by spectroscopic methods, especially 1D and 2D NMR as well as comparison with those reported in the literature for known xanthones. All isolated compounds were evaluated for their cytotoxicity against five human cancer cell lines (KB, HeLa S-3, HT-29, MCF-7 and Hep G2 cell lines). Compounds 2, 5, and 7 showed significant cytotoxic effects against all cell lines with IC values in the range of 0.91-9.93 μM, while 10 exhibited cytotoxicity against the KB, HeLa S-3, and HT-29 cells with IC values of 7.39, 6.07, and 8.11 μM, respectively. Compound 12 exhibited cytotoxicity against both KB and HeLa S-3 cells with IC values of 7.28 and 9.84 μM.