Marine biotopes are considered as a huge reservoir of biodiversity and chemodiversity, the latter potentially providing new treats for health prevention. Among the emphasized marine biocenosis, microorganisms such as microalgae propose suitable solutions to address eco-sustainability or biorefinery topics. The health interests of the xanthophyll diatoxanthin (Dt), a photoprotective and antioxidant pigment synthetized by diatoms, have been recently documented. This study deeply explores the capacity of Dt to intercept cancer progression and addresses the Dt -induced cell death in breast cancer. It is crucial to know which signalling pathway explaining its function is induced by the molecule in the targeted cells. This study disentangled the intracellular effects of Dt in MDAMB231 breast cancer cells. The results highlighted the inhibition of glutathione synthesis through cysteine transport blockage, that in turn, induced an iron accumulation and increase in lipid peroxidation. Those features represent the principal hallmarks of intracellular ferroptosis pathway. Ferroptosis being considered as one of the cell death most promising in fighting cancer development (e.g. in breast cancer) this study reinforces the scientific/biomedical interests on Dt and the diatoms' resource and paves the way to explore its suitability in vivo.