Hesperadin is a multi-kinase inhibitor. It inhibits human Aurora kinase B (IC50 = 250 nM) and its T. brucei homolog Aurora kinase-1 (IC50 = 40 nM) in in vitro kinase assays. Hesperadin (1 μM) inhibits AMPK, LCK, MKK1, MAPKAP-K1, CHK1, and PHK in a panel of 25 kinases. It also inhibits MEKK2 in ATPase and transphosphorylation assays with IC50s of 60 and 34 nM, respectively. Hesperadin (50-100 nM) induces polyploidy and defects in cytokinesis and spindle assembly as well as inhibits proliferation of HeLa cells and overrides mitotic arrest induced by paclitaxel or monastrol . Hesperadin also induces toxicity in HepG2 cells with a toxic concentration (TC50) value of less than 0.2 μM. It inhibits replication of clinical isolates of influenza A and B viruses with EC50s ranging from 0.22 to 2.21 μM in a plaque formation assay. Hesperadin inhibits the growth of T. brucei, L. major promastigotes and amastigotes, and P. falciparum with EC50 values ranging from 0.01 to 2.37 μM, but has less activity against T. cruzi (EC50 = 39 μM).