Compound	R5	R7	a/b	Min. DNA un-winding conc.a (μg/mL)	Decatanation inhib.b (μg/mL)	A549c CC50 (μg/mL)	P388d CC50 (μg/mL)	P388/ ADRe (MDR) CC50 (μg/mL)
56j	H	B	H/H	3	2	0.59	0.04	0.39
57	H	C	H/H	128	>100	2	0.5	*
58	H	A	H/Me	*	*	0.12	0.038	0.24
59	H	A	Me/Me	*	*	0.034	0.012	*
60	H	A	H/OMe	*	*	0.29	0.05	*
61	H	A	H/Ph	*	*	0.16	0.07	*
62	NH2	A	H/H	*	*	0.069	0.0053	*
63	NH2	B	H/H	*	*	0.10	0.0047	*
64	NHMe	A	H/H	*	*	0.39	0.039	*
65	NH2	D	H/H	*	*	0.06	0.030	*
66	NHMe	D	H/H	*	*	1.1	0.79	*
67	NMe2	D	H/H	*	*	6.4	3.9	*

^a Measured at 10mM MgCl₂; ^b drug concentration that inhibits 50% of the conversion of catenated to decatenated k-DNA catalyzed by calf thymus topoisomerase II; ^c human breast cancer cell line; ^d murine leukemia cell line; ^e adriamycin resistant/multidrug resistant; ^f doxorubicin (adriamycin); ^g 55 = A-62176 (racemate); ^h R-enantiomer of 55; ⁱ S-enantiomer of 55; ^j 56 = A-74932 (diasteromeric mixture); *data not reported.