Topoisomerase II inhibitor 18 (Compound IV) is a Quinoxaline derivative, which inhibits topoisomerase II with IC 50 of 7.5 μM. Topoisomerase II inhibitor 18 inhibits proliferation, cell cycle at S phase and induces apoptosis in PC-3 cells. Topoisomerase II inhibitor 18 reveals antitumor activity against cancer.