Ferrocenyl ferroptosis inducers as an emerging class of anticancer agents: a mini review.

Ferroptosis is one of the regulated cell death pathways. Molecular mechanisms underlying ferroptosis involve iron-dependent lipid peroxidation, which results in cell-deleterious membrane damage. Ferroptosis-inducing agents have been identified as attractive candidates for anticancer drug development as they can bypass drug resistance in cancer cells. Among pro-ferroptotic agents are many organometallic complexes, including ferrocenyl compounds. In this review, we demonstrate that suitably designed ferrocene-containing molecules can induce ferroptosis in different cancer cell types both in vitro and in vivo. Their pro-ferroptotic activity is triggered by diverse initiating factors through different mechanisms (e.g. redox activation, thermal and light activation, and GPX4 inhibition combined with ROS overproduction). Moreover, ferrocenyl bioconjugates are often cancer-cell-selective and trigger ferroptosis in combination with other regulated cell-death pathways, such as apoptosis and immunogenic cell death. Dual or multimodal anticancer activity mechanisms are sought after in modern anticancer therapy approaches as they help to overcome the problem of drug resistance. Research on ferrocene-based ferroptosis inducers, however, is still in the early stage. Hence, more time and effort are needed to fully elucidate the potential of ferrocenes as ferroptosis initiators in cancer therapy.