BODI-Pt, a Green-Light-Activatable and Carboplatin-Based Platinum(IV) Anticancer Prodrug with Enhanced Activation and Cytotoxicity

Platinum drugs are widely used in clinics to treat various types of cancer. However, a number of severe side effects induced by the nonspecific binding of platinum drugs to normal tissues limit their clinical use. The conversion of platinum(II) drugs into more inert platinum(IV) derivatives is a promising strategy to solve this problem. Some platinum(IV) prodrugs, such as carboplatin-based tetracarboxylatoplatinum(IV) prodrugs, are not easily reduced to active platinum(II) species, leading to low cytotoxicity in vitro. In this study, we report the design and synthesis of a carboplatin-based platinum(IV) prodrug functionalized with a boron dipyrromethene (bodipy) ligand at the axial position, and the ligand acts as a photoabsorber to photoactivate the platinum(IV) prodrug. This compound, designated as BODI-Pt, is highly stable in the dark but quickly activated under irradiation to release carboplatin and the axial ligands. A cytotoxic study reveals that BODI-Pt is effective under irradiation, with cytotoxicity 11 times higher than that in the dark and 39 times higher than that of carboplatin in MCF-7 cells. Moreover, BODI-Pt has been proven to kill cancer cells by binding to the genomic DNA, arresting the cell cycle at the G₂/M phase, inducing oncosis, and generating ROS upon irradiation. In summary, we report a green-light-activatable and carboplatin-based Pt(IV) prodrug with improved cytotoxicity against cancer cells, and our strategy can be used as a promising way to effectively activate carboplatin-based platinum(IV) prodrugs.