N,N-Dimethyl-idarubicin-trisaccharide (compound 26) is an efficient intercalating agent. N,N-Dimethyl-idarubicin-trisaccharide shows excellent cytotoxicity against ABCG2-overexpressing and ABCB1-overexpressing cells with IC 50 s of 19 and 32 nM, respectively.