Interaction of a Triruthenium ortho-Metallated Phenazine with Cytochrome P450 Enzymes

The triruthenium ortho-metallated phenazine [Ru₃O(CH₃COO)₅(py)₂(dppzCl)]PF₆ (1, py = pyridine; dppz-Cl = 7-chlorodipyrido[3,2-a:2’,3’-c]phenazine) is a potential metallo-drug candidate with in vitro anticancer and trypanosomicidal activities. It also showed strong interactions with deoxyribonucleic acid (DNA) and human serum albumin due to the presence of the planar and π-conjugated phenazine in its structure. Pursuing our interest in compound 1 behavior in a biological environment, we described its interaction with the cytochrome P450 (CYP450) enzymes present in human liver microsomes through a preliminary in vitro metabolism assay. This study showed that the human liver microsomes metabolized compound 1 in a concentration dependent manner. A phenotyping study suggests that CYP3A is the primary enzyme involved in the interaction, even though other isoforms metabolized 1 in a minor extent. It is worth mentioning that the results of phenotyping using supersomes should be interpreted cautiously, taking into account the inhibitory effect of the surfactant employed. Blind molecular docking results agreed with the experimental trend, showing the highest interactive profile with the isoforms CYP3A4 and 3A5, and suggested hydrophobic, π-stacking, and hydrogen bonds as the primary intermolecular forces responsible for the protein-compound interaction.

Keywords:
triruthenium ortho-metallated phenazine; metallo-drug; cytochrome P450; in vitro metabolism; phenotyping; blind molecular docking