Aim: The objective of this work was to synthetize the dicarboxylic acid metabolite of mitoxantrone (MTX) to further investigate its cardiotoxicity in H9c2 differentiated cells.
Introduction: Drug metabolism can result in active or toxic metabolites that can lead to side effects, namely cardiotoxicity.1 MTX, an antineoplastic that belongs to the synthetic anthracenediones,2 is used to treat breast cancer, acute leukaemias, and acute lymphomas in adults.3 Nowadays, it is also used to treat aggressive multiple sclerosis. One of the most frequent and relevant MTX side effect is cardiotoxicity. Previously, we found the MTX-naphthoquinoxaline metabolite (NAPHT) to be less cardiotoxic than MTX.4 One of the main human MTX metabolites was identified as the dicarboxylic acid resulting from the oxidation of the terminal hydroxyl groups of the side chains.5 However, its putative cardiotoxicity was not yet assessed. Herein, the synthesis and structure elucidation of the dicarboxylic acid metabolite will be presented.
Methods: The total synthesis of the metabolite involved five steps, starting from chrysazin. The enzymatic reaction was accomplished through the horseradish peroxidase (HRP)-catalysed H2O2 and the studies of the oxidative reactions involved sodium tungstate, chromium trioxide, sodium nitrite, and potassium permanganate.
Results: In order to obtain the carboxylic derivative, several approaches were undertaken, namely, total synthesis from a commercial available anthraquinone, as well as enzymatic and oxidative reactions from MTX. Different derivatives were obtained. The structure elucidation of the intermediates was established by spectroscopic techniques and the characterization of the dicarboxylic acid metabolite is ongoing.
Conclusion: The synthesis of the dicarboxylic acid metabolite was only achieved by the multistep approach. Future work will involve cardiotoxicity studies of this metabolite in H9c2 differentiated cells.
Acknowledgements: We thank FCT/MCTES and ERDF through the COMPETE–POFC programme, under the Strategic Funding UID/Multi/04423/2013, the project PTDC/MAR-BIO/4694/2014 (POCI-01-0145-FEDER-016790; 3599-PPCDT) and PTDC/DTP-FTO/1489/2014 (POCI-01-0145-FEDER-016537) in the framework of PT2020, to INNOVMAR (NORTE-01-0145-FEDER-000035, NOVELMAR), supported by NORTE 2020, under PORTUGAL 2020, through ERDF. To Dr. S Cravo for technical assistance.