In order to develop potential anti-cancer agents that act on topoisomerase II and DNA, we have synthesized 12 new xanthone derivatives. In the cytotoxicity test, compounds 17 and 31 exhibited 2-to 7-fold stronger inhibitory activity than adriamycin against most cancer cell lines tested. Halohydrin group-tethered compounds 19, 21 and 27 showed comparable topoisomerase II inhibitory activity to etoposide at 100μM concentration. In the DNA cross- ...