Table 3. Selectivity of the Most Active 17β-HSD2 Inhibitors toward 17β-HSD1.

compound	17β-HSD2 activity (IC50)	17β-HSD1 activity (IC50 or remaining activity at 20 μM)	selectivity factor
nordihydroguaiaretic acid (1)	0.38 ± 0.04 μM	5.5 ± 1.3 μM	15
curcumin (3)	1.73 ± 0.20 μM	52.2 ± 7.1%	∼12
(−)-dihydroguaiaretic acid (4)	0.94 ± 0.02 μM	7.7 ± 2.2 μM	8
isoliquiritigenin (6)	0.36 ± 0.08 μM	2.83 ± 0.80 μM	8
lupinalbin A (8)	1.52 ± 0.15 μM	0.049 ± 0.019 μM	0.03
2′-hydroxygenistein (9)	2.03 ± 0.37 μM	1.09 ± 0.06 μM	0.5
rosmarinic acid (11)	3.72 ± 0.17 μM	n.i.a	>5
ethyl vanillate (12)	1.28 ± 0.26 μM	n.i.	>15
2-(3-chloro-4-hydroxyphenyl)-N-phenethylacetamide (13)	1.57 ± 0.16 μM	n.i.	>12
N-benzyl-2-(3-chloro-4-hydroxyphenyl)acetamide (16)	3.42 ± 0.74 μM	n.i.	>5
N-(2-(1H-indol-3-yl)ethyl)-2-(3-chloro-4-hydroxyphenyl)acetamide (17)	0.98 ± 0.24 μM	n.i.	>20
2-(3-chloro-4-hydroxyphenyl)-N-(2-chlorobenzyl)acetamide (18)	0.78 ± 0.16 μM	54.8 ± 5.8%	∼25

^an.i., no inhibition.