Assay Method Information

Assay Name:  In Vitro CYP Inhibition Assay
Description:  P450 enzyme inhibition was measured using human cDNA-expressed CYP3A4, 2D6, 2C19, 2C9, and 1A2 recombinant enzymes and fluorogenic substrates (coumarin analogues) that are converted to fluorescent products. The analogues utilized for each isoenzyme are as follows: 7-benzyloxy-trifluoromethylcoumarin, (BFC) for 3A4; 3-[2-(N,N-diethyl-N-methyl amino)ethyl]7-methoxy-4-methylcoumarin, (AMMC) for 2D6; 3-cyano-7-ethoxycoumarin, (CEC) for 2C19 and 1 A2; and 7-methoxy-4-trifluoro-methylcoumarin, (MFC) for 2C9. These substrates were utilized at a single concentration (either 50 uM or 75 uM) at or near the apparent Km for each substrate. Fluorescence intensity was measured using a Wallac 1420 Victor3 Multi-label Counter Model (PerkinElmer, Wellesley, Mass.), with an excitation wavelength filter of 405 nm, and an emission filter of 460 nm (535 nm for the 3A4 and 2C9 substrates). Compound stocks (10 mM in a 4:1 ratio of acetonitrile:DMSO) were tested in this study using an 8-point dose response curve in duplicate (ranging from 0.15 uM-20.0 uM). The concentration of acetonitrile was kept constant at 0.4%, and the reaction was carried out at 37° C. for 30 minutes.
Affinity data for this assay
 

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