Table 1.

NQO1 induction potency and toxicity of sulfoxythiocarbamate analogs in three cell lines including murine hepatoma cells (Hepa1c1c7), human retinal pigment epithelial cells (ARPE-19), and murine keratinocytes (PE)

Hepa1c1c7									ARPE-19			PE
Name	CD, μM	LD50, μM	Name	CD, μM	LD50, μM	Name	CD, μM	LD50, μM	Name	CD, μM	LD50, μM	Name	CD, μM	LD50, μM
4a	94	> 200	4j	7.3	> 50	8a	5.4	115	4f	4.8	> 200	4f	13	> 200
4b	35	> 200	4k	9.8	> 50	8b	5.4	120	4i	3.8	21	8a	2.5	128*
4c	43	> 200	4l	ND	—	8c	12	> 50	4o	1.7	29	8b	2.8	131*
4d	64	> 200	4m	12.6	> 50	8d	2.1	12	8a	1.5	120*	8f	3.8	50
4e	43	> 200	4n	ND	—	8e	7.1	> 50	8b	1.8	123*	SF	0.25	13*
4f	13	> 200	4o	4.3	37	8f	5.5	43	8f	5	38
4g	5.3	> 50	4p	8.2	> 50	SF	0.23	18	SF	1.4	14*
4h	3.8	32	4q	7	12.5
4i	2.8	16	4r	2.6	10

Cells were grown in 96-well plates for 24 h and incubated with serial dilutions of each compound for 48 h. NQO1 activity and total protein concentrations were determined in cell lysates by Prochaska method (26) and the BCA assay, respectively. The specific NQO1 activity or total protein concentrations were plotted vs. compound concentrations with values of mean ± SEM. (n = 8). The concentrations that give a twofold increase of NQO1 activity or 50% decrease of total protein concentrations when compared to control were determined as CD or LD₅₀. Standard errors were <  ± 20% for values shown. ND, not detemined; less than twofold induction.

^*Values were determined by extrapolation.