HNE inhibitory activity in an enzymatic assay, antiradical effects in a cell-based assay of ROS production, and cytotoxicity of new Se-derivatives 3a–d, 4a–p, 6 and 8.

Comp.	R	HNE inhibition	Antiradical activity	Cyto-toxicity
		IC50a (μM)
3b	COOCH2CH3	N.A.b	1.8 ± 0.2	N.A.b
3c	CONH–cC3H5	N.A.b	9.7 ± 1.4	8.0 ± 1.9
3d	CONH-3-CH3-Ph	N.A.b	N.A.b	N.A.b
4a	CH3	7.7 ± 2.3	0.42 ± 0.06	10.8 ± 2.4
4b	C2H5	2.6 ± 0.2	0.18 ± 0.05	8.5 ± 1.8
4c	CH2CH2CH3	2.4 ± 0.4	0.33 ± 0.08	4.9 ± 0.6
4d	iC3H7	1.2 ± 0.1	0.60 ± 0.2	9.6 ± 2.2
4e	C(CH3)3	1.8 ± 0.1	2.6 ± 0.4	13.6 ± 3.1
4f	nC4H9	0.9 ± 0.2	0.70 ± 0.2	4.2 ± 0.9
4g	nC5H11	3.0 ± 0.4	N.A.b	N.A.b
4h	OC2H5	N.A.b	2.5 ± 0.4	15.2 ± 3.2
4i	CH2COOCH2CH3	N.A.b	1.0 ± 0.3	8.1 ± 1.7
4j	cC3H5	1.4 ± 0.1	0.05 ± 0.01	10.4 ± 2.4
4k	cC5H9	2.8 ± 0.2	1.4 ± 0.2	11.8 ± 2.8
4l	cC6H11	24.1 ± 4.8	1.1 ± 0.1	12.4 ± 3.4
4m	Ph	2.3 ± 0.4	N.T.c	N.T.c
4n	3-CH3-Ph	10.9 ± 2.1	7.0 ± 1.3	N.A.b
4o	4-OCH3-Ph	8.7 ± 1.2	N.T.c	N.T.c
4p	3-Thienyl	N.A.b	14.3 ± 2.7	N.A.b
8	NH–cC3H5	N.A.b	0.90 ± 0.3	5.9 ± 1.6
6	—	2.7 ± 0.5	6.4 ± 0.4	N.A.b
Ebselen (3a)	H	N.A.b	0.15 ± 0.02	9.5 ± 2.5
Sivelestat	—	0.044	—	N.A.b

^aIC₅₀ values are presented as the mean ± SD of three independent experiments.

^bN.A.: no inhibitory activity was found at the highest concentration of compound tested (50 μM) or no cytotoxicity activity was found at the highest concentration of compound tested (25 μM).

^cN.T.: not tested.