TABLE 2.

Derivative 4 sensitizes the NCI-H460/R cell line to doxorubicin.

Combined treatments	IC50 for DOX (µM)	Relative reversal factor
DOX	2.774 ± 0.025	—
4 (0.5 µM) + DOX	0.823 ± 0.016	3.37
4 (1.0 µM) + DOX	0.594 ± 0.017	4.67
4 (2.0 µM) + DOX	0.608 ± 0.020	4.56

DOX concentrations used in the experiments: 0.1, 0.25, 0.5, 1 and 2.5 μM.