Table 1. Cytotoxicity of paullone ligands HL¹ and HL², and copper(ii) complexes 1 and 2 in six human tumour cell lines.

	IC50, a 96 h
	HL1	1	HL2	2
A549	0.22 ± 0.02	0.19 ± 0.04	0.063 ± 0.009	0.093 ± 0.009
CH1	0.081 ± 0.002	0.056 ± 0.003	0.02 ± 0.003	0.037 ± 0.007
SW480	0.17 ± 0.03	0.15 ± 0.02	0.27 ± 0.05	0.39 ± 0.05
N87	0.22 ± 0.04	0.18 ± 0.02	0.027 ± 0.009	0.056 ± 0.013
SK-Mel 28	0.70 ± 0.03	0.64 ± 0.07	0.031 ± 0.005	0.047 ± 0.011
T47D	0.13 ± 0.01	0.12 ± 0.02	0.13 ± 0.03	0.22 ± 0.05

^a50% inhibitory concentrations (means ± standard deviations from at least three independent experiments), as obtained by the MTT assay using exposure times of 96 h.