Tumour selective redox activity of economically synthesised Ferromarin in triple-negative breast cancer.

Breast cancer is one of the most prevalent malignancies worldwide, particularly among women, with triple-negative breast cancer (TNBC) representing the most aggressive subtype owing to the lack of targeted therapies and its poor clinical prognosis. Conventional chemotherapeutic agents are often limited by non-selective cytotoxicity, dose-limiting toxicities, and complex multistep, metal-catalysed, and stereocontrolled synthetic routes, highlighting the need for more sustainable therapeutic alternatives. Herein, we report the development of a novel therapeutic molecule, 2-amino-4-ferrocene-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile (Ferromarin), synthesized via a one-pot, metal-free, room-temperature protocol. Ferromarin exhibited potent cytotoxic activity against TNBC (4T1) cells while demonstrating substantially lower toxicity toward normal L929, C2C12, and H9C2 cells, indicating selective anticancer activity. Mechanistic investigations suggest that its cytotoxic effects are associated with increased intracellular reactive oxygen species (ROS) generation, mitochondrial membrane depolarization, and DNA double-strand damage, supporting the involvement of oxidative stress and mitochondrial dysfunction in the observed anticancer activity. A wound-healing assay demonstrated that Ferromarin significantly inhibited 4T1 cell migration, indicating anti-metastatic potential. In addition, Ferromarin effectively penetrated and suppressed tumour growth in three-dimensional (3D) multicellular spheroid models. Furthermore, intratumoural administration in an orthotopic 4T1 breast tumour model produced marked tumour regression with excellent localized retention, highlighting the promise of Ferromarin as a selective therapeutic candidate for the treatment of TNBC.