A Ligand-Based Drug Design. Discovery of 4‑Trifluoromethyl-7,8-pyranocoumarin as a Selective Inhibitor of Human Cytochrome P450 1A2

Abstract

In humans, cytochrome P450 1A2 is the major enzyme metabolizing environmental arylamines or heterocyclic amines into carcinogens. Since evidence shows that planar triangle-shaped molecules are capable of selectively inhibiting P450 1A2, 16 triangular flavone, and coumarin derivatives were designed and synthesized for these studies. Among these compounds, 7,8-furanoflavone time-dependently inhibits P450 1A2 with a <i>K</i>_I value of 0.44 μM. With a 5 min preincubation in the presence of NADPH, 0.01 μM 7,8-furanoflavone completely inactivates P450 1A2 but does not influence the activities of P450s 1A1 and 1B1. Another target compound, 7,8-pyrano-4-trifluoromethylcoumarin, is found to be a competitive inhibitor, showing high selectivity for the inhibition of P450 1A2 with a <i>K</i>_i of 0.39 μM, 155- and 52-fold lower than its <i>K</i>_i values against P450s 1A1 and 1B1, respectively. In yeast AhR activation assays, 7,8-pyrano-4-trifluoromethyl­coumarin does not activate aryl hydrocarbon receptor when the concentration is lower than 1 μM, suggesting that this compound would not up-regulate AhR-caused P450 enzyme expression. In-cell P450 1A2 inhibition assays show that 7,8-pyrano-4-trifluoromethyl­coumarin decreases the MROD activity in HepG2 cells at concentrations higher than 1 μM. Thus, using 7,8-pyrano-4-trifluoromethyl­coumarin, a selective and specific P450 1A2 action suppression could be achieved, indicating the potential for the development of P450 1A2-targeting cancer preventive agents