Synthesis of Di-Pyropheophorbide-a-platinum(ii) Complex and the in Vitro Cytotoxicity Against TC-1 Tumor Cells

This report focuses on the conjugation of a chemotherapeutic drug and photodynamic therapy (PDT) agent with the intention of obtaining an optimal anticancer agent for use in combination cancer treatment. We have used pyropheophorbide-a (PPa) as a PDT agent, which was linked with ethylenediamine using carbodimide/N-hydroxysuccinicimide coupling reagents to obtain a resulting reactive amine group. Next, the free amine-bearing PPa and potassium tetrachloroplatinate (K2PtCl4) were reacted in aqueous solution to obtain PPa-cisplatin complex. Subsequently, the PPa-based platinum complex was characterized through several methods including NMR spectroscopy, mass spectrometer and UV absorption spectroscopy and its in vitro cytotoxicity and cellular uptake were evaluated on the TC-1 cancer cell line. The results indicated that the conjugate has a greater cytotoxic effect in the dark than cisplatin, even though its phototoxic effect was slightly lower than that of free photosensitizer; in addition, the cellular uptake of complex at 0.125 and 0.25 μM was higher than that of free photosensitizer.