Table 2. Inhibitory Activity against rhIDO1 and Cellular Kynurenine Production by Carbonothioates (4c–4f), Carbonodithioates (5a–5l), and Cyanocarbonimidodithioates (6a–6b).

cpd	R2	R3	rhIDO1 IC50 (μM)	KYN productiona IC50 (μM)	cytotoxb IC50 (μM)
4c	H	CH2CH2NH2 HCl	3.3	>10	>10
4d	2,4-Cl2	CH2CH2NH2 HCl	0.20	2.2	>10
4e	H	CH2CH2NHBoc	3.0	>10	>10
4f	2,4-Cl2	CH2CH2NHBoc	0.59	1.4	>10
5a	H	CH2CH2NH2 HCl	5.3	>10	>10
5b	2,4-Cl2	CH2CH2NH2 HCl	0.83	1.2	>10
5c	H	CH2CH2NHBoc	>10	>10	>10
5d	2,4-Cl2	CH2CH2NHBoc	1.6	1.1	>10
5e	2,4-Cl2	CH2CH2OH	0.31	0.39	>10
5f	H	3-HO-C6H4	0.60	2.6	>10
5g	2,4-Cl2	3-HO-C6H4	0.10	0.44	>10
5h	H	4-HO-C6H4	0.90	3.6	>10
5i	2,4-Cl2	4-HO-C6H4	0.10	0.40	>10
5j	2,4-Cl2	4-HOCH2–C6H4	0.12	0.27	>10
5k	2,4-Cl2	4-MeO-C6H4	0.20	0.27	>10
5lc			>100	>10	>10
6a	H	Me	>10	6.1	>10
6b	2,4-Cl2	Me	0.90	3.7	>10

^aKynurenine production in A431 cells.

^bCytotoxicity to A431 cells.

^cPurchased commercial product.