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Table 1 IC50 values and inhibition constants (Ki) for ketoconazole and xenoestrogens on CYP1A- and CYP3A activities assayed in vitro.

From: Interactions between xenoestrogens and ketoconazole on hepatic CYP1A and CYP3A, in juvenile Atlantic cod (Gadus morhua)

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. 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.