Inhibitory Properties of Trapping Agents: Glutathione, Potassium Cyanide, and Methoxylamine, Against Major Human Cytochrome P450 Isoforms

Title: Inhibitory Properties of Trapping Agents: Glutathione, Potassium Cyanide, and Methoxylamine, Against Major Human Cytochrome P450 Isoforms

Volume: 3 Issue: 2

Author(s): Chenghong Zhang, Susan Wong, Erlie M. Delarosa, Jane R. Kenny, Jason S. Halladay, Cornelis E. Hop and Siamak Cyrus Khojasteh-Bakht

Affiliation:

Keywords: Trapping agents, glutathione, cyanide, methoxylamine, P450 inhibition, reactive metabolites

Abstract: In the early stages of drug discovery, the formation of reactive metabolites is often assessed by co-incubating the drug in liver microsomes with a trapping agent in the presence of NADPH. Our group assessed the capability of commonly used trapping agents to reversibly inhibit major cytochrome P450 (CYP) isoforms. Glutathione and cyanide did not inhibit the enzymes at concentrations up to 10 mM; however methoxylamine did show inhibition, with IC50 values of 0.53 mM for CYP1A2, 4.12 mM for CYP2C9, 2.04 mM for CYP2C19, 9.72 mM for CYP2D6, and 1.26 and > 10 mM for CYP3A4/5 (for testosterone and midazolam, respectively, as substrates).

Cite this article as:

Zhang Chenghong, Wong Susan, Delarosa M. Erlie, Kenny R. Jane, Halladay S. Jason, Hop E. Cornelis and Khojasteh-Bakht Cyrus Siamak, Inhibitory Properties of Trapping Agents: Glutathione, Potassium Cyanide, and Methoxylamine, Against Major Human Cytochrome P450 Isoforms, Drug Metabolism Letters 2009; 3 (2) . https://dx.doi.org/10.2174/187231209788654126