Polypyridyl Ru(II) tamoxifen analogues: Estrogen receptor-targeted dual photodynamic and chemotherapeutic agents

The use of targeted chemotherapeutic agents and of locally active treatments such as photodynamic therapy (PDT), are strategies to tackle the side effects and enhance the effectiveness of anticancer treatments. In this context, the development of multifunctional drugs, which combine targeted chemotherapy and photosensitizing capabilities, has garnered increased attention. Herein, we introduce two polypyridyl ruthenium(II) compounds featuring tamoxifen-related ligands (RuTamOMe and RuTamOH) targeting the estrogen receptor α (ERα) and able to generate singlet oxygen via energy transfer. The compounds display enhanced phototoxicity, tested in different cell lines (A375 melanoma, MDA-MB-231 triple negative adenocarcinoma and MCF-7 ER+ breast cancer cells) and examined in terms of the ERα expression dependence. Computational studies were also performed, corroborating the suitability of the compounds to target ER, maintaining tamoxifen's affinity for the receptor binding site, and revealing a minimal influence of the stereochemical configuration of the compounds on their targeting capabilities. Altogether, our results highlight the potential of hybrid Ru(II) polypyridyl compounds as suitable platforms for generating targeted metallodrugs with photosensitizing capabilities.