. Author manuscript; available in PMC: 2013 Oct 11.

Published in final edited form as: J Med Chem. 2012 Sep 24;55(19):8464–8476. doi: 10.1021/jm300930n

Table 1.

Summary of IC₅₀ and EC₅₀ Measurements of Newly Designed C6β-Alkoxy/2-Alkynyloxy Series of Steroidal Aromatase Inhibitors and Three Known Inhibitors as Controls^a

Compounds		IC₅₀ (nM)	95% Confidence Interval for IC₅₀ (nM)	EC₅₀ (nM)	95% Confidence Interval for EC₅₀ (nM)
Compounds	R Group	IC₅₀ (nM)	95% Confidence Interval for IC₅₀ (nM)	EC₅₀ (nM)	95% Confidence Interval for EC₅₀ (nM)
2	Me	5200	4700 to 5500	-
3	Et	18100	13100 to 25200	-
4		112.3	78.2 to 161.3	1.7	1.2 to 2.2
5		11.8	9.3 to 14.9	0.03	0.02 to 0.06
6		83.0	74.5 to 93.9	3.4	2.4 to 4.7
7		181.1	164.0 to 200.0	5.4	3.2 to 7.3
8		2180	1750 to 2710	15.7	10.1 to 22.9
9		20.0	18.1 to 22.0	0.3	0.2 to 0.4
Exemestane (EXM)		50.1	40.9 to 61.4	5.6	2.7 to 6.5
Formestane		48.6	33.6 to 71.1	-	-
Letrozole (LTZ)		9.9	9.3 to 10.5	0.004	0.003 to 0.007

The aromatase specific activity is measured as number of moles of ASD converted to E1 per unit mass of the enzyme per unit time and typically ranges between 25 and 50 nmol min⁻¹ mg⁻¹.