Abstract

The elucidation of the metabolic pathways and the biotransformation mechanisms of potential drugs is a crucial point in drug development. It allows to know the activation routes of the new biologically active compounds, especially in respect to their possible toxicity. Generally, in vivo or in vitro experiments with liver microsomes or hepatocytes are performed. However, these testing schemes are tedious, time consuming and of limited reproducibility. The combination of electrochemistry coupled on-line to mass spectrometry forms a powerful analytical technique with unique applications in the fields of drug metabolism. In an electrochemical flow-through cell, the oxidative metabolism of xenobiotics is simulated. The cell is used in on-line set-up with mass spectrometry, so that an identification of reactive and stable metabolites is possible. Here, we present the benefits of electrochemical metabolism simulation for C-1311 and C-1748, representative antitumor acridines developed in our team. The studied compounds exhibit high cytotoxic activity against a broad spectrum of cell lines in vitro and of transplantable animal tumors. The previous studies on molecular mechanisms of their biochemical action showed that metabolic activation might be a prerequisite stage for the following interactions of these agents with cell macromolecules. Next, we showed that both of them were metabolized by enzymes originating from rat and human liver microsomes. In the presented work C-1311 and C-1748 were chosen as the model drugs to investigate oxidative metabolism under electrochemical conditions coupled to mass spectrometry. The results obtained by EC/MS were then compared with conventional in vitro studies with RLMs as well as HLMs. Electrochemical conversion of both acridines into phase I metabolites was successfully achieved. Comparison of MS results from liver cell microsome incubations with MS results from EC studies allowed to demonstrate that some of the most important metabolic products of the studied compounds were detected both in the conventional enzymatic approach and in the EC simulation. Moreover, newly reported metabolic reaction product of C-1748 become accessible. Summing up, the obtained results confirmed that EC/MS is very well-suited for the simulation of the oxidative metabolism of antitumor acridines. It can be a versatile and user friendly tool in drug discovery and development when applied complementary to established in vitro or in vivo approaches.

Authors (5)