Mitoxantrone diacetate is a potent inhibitor of topoisomerase II. Mitoxantrone diacetate also inhibits protein kinase C (PKC) (IC50: 8.5 µM). Mitoxantrone diacetate exhibits antitumour effects and also has an antiorthopoxvirus effect, acting against bovine pox (EC50: 0.25 µM) and monkey pox (EC50: 0.8 µM).