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P1009
Distribution of Cytochrome P450 Activity Across Known Drugs & Diverse Compound Collections
Presenter Henrike Veith, National Institutes of Health, USA
Additional Authors: Noel Southall, Ruili Huang, James Inglese, Christopher Austin, Douglas Auld
Cytochrome P450s (CYP) are a large family of oxidoreductases that function in xenobiotic metabolism as well as steroidogenesis. Typically, CYP activity is measured for a chemical series early in the drug discovery process to assess the clearance of the compound, liabilities due to CYP inhibition, and potential issues regarding drug-drug interactions.  Five isoforms that play a dominant role in drug metabolism are commonly used in this process which includes CYPs, 1A2, 2C9, 2C19, 2D6, and 3A4. Using quantitative High-Throughput Screening (qHTS), an approach that provides concentration-response curves for large compound collections, we measured the AC50s for these five CYPs against a collection containing both known bioactives and diverse compounds. We used a common assay format employing commercially available luminescent-based reagents (Promega). Using qHTS we measured AC50s for ~ 30K compounds for all five isozymes. These included 8,200 from known bioactives and ~20K from a diverse collection. The assay showed good performance (Z’ from 0.35 to 0.72; signal-to-background ratios from 6.9 to 20). The luminescent format eliminated issues such as compound fluorescence common to other formats and a counter-screen against the variant of firefly luciferase used in the detection reagent showed low interference (<0.07% ). Against our “known drugs” and other collections we found the highest activity for CYP 1A2 and 3A4 (~50% active of the library was active in each) and the lowest activity was found for CYP 2C9 (~30%). We will discuss the distribution of activity among the five CYPs and the implication for lead optimization studies.