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

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 KI 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 Ki of
0.39 μM, 155- and 52-fold lower than its Ki 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.