Table 2.

Cytotoxicities of the compounds and 1:1 combinations against melanoma (A375) and normal keratinocytes (HaCat).^a

Compounds and 1:1 Combinations	A375 IC50 µM or nMb	HaCat IC50 µM or nMb	TIc	CId
Artemisinin 2	149.7 ± 3.61	381.3 ± 5.36	2.5
Artemisone 4	95.73 ± 2.31	268.8 ± 1.97	2.8
Elesclomol-Cu(II) 1-Cu	1.72 ± 0.23 nM	4.88 ± 0.56 nM	2.8
Sulfasalazine 8	569.80 ± 2.95	2223 ± 5.37	3.9
Etoposide 9	43.66 ± 1.37	>12970	>297
Artemisone 4 + Elesclomol 1-Cu	2.40 ± 0.47 nM	8.04 ± 0.49 nM	3.4	0.30
Geranylpiperazine-DHA 6	46.94 ± 0.89	105.57 ± 3.99	2.2
6 + Elesclomol 1-Cu	<0.01 nM	2.55 ± 0.41 nM	>255	0.20
6 + Sulfasalazine 8	30.77 ± 0.27	134.3 ± 1.23	4.3	1.60
6 + Etoposide 9	20.88 ± 0.84	102.23 ± 2.67	4.8	0.74
Farnesylpiperazine-DHA 7	32.62 ± 1.08	70.64 ± 1.07	2.1
7 + Elesclomol 1-Cu	<0.01 nM	3.71 ± 0.12 nM	>371	0.16
7 + Sulfasalazine 8	30.43 ± 1.14	61.43 ± 1.12	2	0.92
7 + Etoposide 9	10.87 ± 0.91	48.91 ± 1.01	4.5	0.42

^aResults are reported as inhibitory concentrations IC₅₀ in µM or nM from three independent biological replicates, each performed as technical replicates ± standard deviation (SD).

^bResults from elesclomol-Cu(II) are reported in nM.

^cTherapeutic index (TI) calculated as the fold decrease in IC₅₀ of HaCat cells/IC₅₀ of A375 cells.

^dCombination index (CI): CI<1=synergism; CI=1 additive effect; CI>1=antagonism(Chou and Talalay, 1984; Chou, 2010). The drug interaction is more pronounced the farther a CI value is from 1.