Table 1

IC50 values and inhibition constants (Ki) for ketoconazole and xenoestrogens on CYP1A- and CYP3A activities assayed in vitro.

Compound(s)
IC50(μM)1,a
Ki(μM)1,a
IC50(μM)2,b
Ki(μM)2,b
IC50(μM)3,b

Ketoconazole (KC)
0.6 (0.0)c
0.04 – low [S]
0.3 (0.1)c
0.2
0.4c


0.2 – high [S]



Nonylphenol (NP)
5.2 (1.1)
3.5
160 (40)
Not analysed
35
Ethynylestradiol
20 (1.2)
5.4 – low [S]
40 (7.1)
54 – low [S]
50


10.3 – high [S]

95 – high [S]

KC:NP (1:5)
1.3 (0.2):6.2 (1.0)
Not analysed
5.3 (1.1):25.0 (5.3)
Not analysed
Not analysed

1 Hepatic Microsomal CYP1A activity; 2 Hepatic Microsomal CYP3A activity; 3 cDNA Expressed Human CYP3A4; a Substrate [S] = 7-Ethoxyresorufin; b [S] = 7-Benzyloxy-4-[trifluoromethyl]-coumarin; c Published in [22]. Each IC50 value represents the mean from 2–4 separate assays, followed by the SD, in brackets. The Ki values are estimated from one representative Dixon plot.

Hasselberg et al. Comparative Hepatology 2005 4:2   doi:10.1186/1476-5926-4-2