iNOS/TopoI-IN-1 (compound AuL9) is a multi-target hybrid molecule with anti-tumor, anti-inflammatory and antioxidant activities. iNOS/TopoI-IN-1 inhibits the growth of breast cancer cells MCF-7 and MDA MB-231 in vitro with IC 50 of 3.5 μM and 6.3 μM, respectively, and induces DNA damage and apoptosis of breast cancer cells by inhibiting human topoisomerase I ( TopoI ) ( K i =2.72 μM). In addition, NOS/TopoI-IN-1 inhibits the expression of iNOS by inhibiting the activation of NF-kB ( K i =1.49 μM).