New Oxaliplatin-Pyrophosphato Analogs with Improved In Vitro Cytotoxicity

• Main Authors: Alessandra Barbanente, Rosa Maria Iacobazzi, Amalia Azzariti, James D. Hoeschele, Nunzio Denora, Paride Papadia, Concetta Pacifico, Giovanni Natile, Nicola Margiotta
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Molecules
• Subjects: cisplatin; oxaliplatin; phosphaplatins; pyrophosphate; bone tumors; antitumor drugs
• Online Access: https://www.mdpi.com/1420-3049/26/11/3417

Two new Pt(II)-pyrophosphato complexes containing the carrier ligands <i>cis</i>-1,3-diaminocyclohexane (<i>cis</i>-1,3-DACH) and <i>trans</i>-1,2-diamine-4-cyclohexene (1,2-DACHEX), variants of the 1<i>R</i>,2<i>R</i>-diaminocyclohexane ligand present in the clinically used Pt-drug oxaliplatin, have been synthesized with the aim of developing new potential antitumor drugs with high bone tropism. The complexes are more stable at physiological pH than in acid conditions, with Na₂[Pt(pyrophosphato)(<i>cis</i>-1,3-DACH)] (<b>1</b>) slightly more stable than [Pt(dihydrogenpyrophosphato)(1,2-DACHEX)] (<b>2</b>). The greater reactivity at acidic pH ensures a greater efficacy at the tumor site. Preliminary NMR studies indicate that <b>1</b> and <b>2</b> react slowly with 5’-GMP (used as a model of nucleic acids), releasing the pyrophosphate ligand and affording the bis 5’-GMP adduct. In vitro cytotoxicity assays performed against a panel of four human cancer cell lines have shown that both compounds are more active than oxaliplatin. Flow cytometry studies on HCT116 cells showed that the pyrophosphato compounds with the non-classical 1,3- and 1,4-diaminocyclohexane ligands (<b>1</b> and <b>4</b>) are the most capable to induce cells’ death by apoptosis and necrosis.