Cytotoxic Activity of a Niclosamide–Caffeic Acid Multicomponent Cocrystal in T47D Breast Cancer Cells

Objective: This study aimed to evaluate the cytotoxic activity of a niclosamide–caffeic acid multicomponent cocrystal against T47D breast cancer cells. Methods: The multicomponent cocrystal was prepared using the solvent-drop grinding method. Cytotoxic activity was assessed using the Microculture Tetrazolium Test (MTT) assay. Results: The results demonstrated that both niclosamide alone and the niclosamide–caffeic acid multicomponent cocrystal exhibited cytotoxic effects against T47D cells, with IC50 values of 2.92 μg/mL and 2.50 μg/mL, respectively. Microplate spectrophotometric analysis confirmed a concentration-dependent decrease in cell viability for both treatments. Notably, the niclosamide–caffeic acid multicomponent cocrystal displayed a more pronounced cytotoxic effect than niclosamide alone. Conclusions: These findings suggest that the formation of niclosamide–caffeic acid multicomponent crystals may enhance anticancer potential and warrant further investigation as a promising therapeutic approach for breast cancer treatment. Keywords: breast cancer, niclosamide, caffeic acid, multicomponent crystal, cytotoxicity, T47D cells, MTT assay.