Visible‐Light‐Induced Annihilation of Tumor Cells with Platinum–Porphyrin Conjugates

Abstract Despite the extensive use of porphyrins in photodynamic therapy (PDT), tetraplatinated porphyrins have so far not been studied for their anticancer properties. Herein, we report the synthesis of such novel platinum–porphyrin conjugates as well as their photophysical characterization and in vitro light‐induced anticancer properties. These conjugates showed only minor cytotoxicity in the dark, but IC 50 values down to 19 n M upon irradiation with light at 420 nm.These values correspond to an excellent phototoxic index (PI=IC 50 in the dark/IC 50 in light), which reached 5000 in a cisplatin‐resistant cell line. After incubation with HeLa cells, nuclear Pt concentrations were 30 times higher than with cisplatin. All of these favorable characteristics imply that tetraplatinated porphyrin complexes are worthy of exploration as novel PDT anticancer agents in vivo.