Development and Characterization of Copaiba Oil‐Loaded Polymeric Nanocapsules With Enhanced Antitumor Activity Against Breast Cancer Cells

Breast cancer is one of the most common malignancies worldwide, and its treatment is often limited by tumor resistance and drug‐related toxicity. Natural products have emerged as promising sources of novel anticancer compounds. Copaiba oil (OC), extracted from Copaifera species, has demonstrated anticancer potential, but its application is restricted by volatility and lipophilicity. To address these limitations, a polymeric nanocapsule formulation containing copaiba oil (NPOC) was developed, characterized, and evaluated in breast cancer cell lines. NPOC exhibited suitable physicochemical parameters, efficient cellular uptake, and improved stability. Cytotoxicity assays showed that NPOC was significantly more active against MCF‐7 and MDA‐MB‐231 cells than free OC, while being less toxic to non‐tumorigenic MCF‐10A and HEK‐293 cells. indicated activation, including membrane blebbing, nuclear condensation, and mitochondrial depolarization, indicated the activation of the intrinsic apoptotic pathway. Redox assays further suggested that NPOC induces cytotoxicity through oxidative stress. In 3D spheroid models, NPOC effectively reduced tumor size and inhibited cell migration. These effects surpassed those observed for free OC. These findings demonstrate that NPOC enhances the antitumor activity and selectivity of OC, supporting its potential as a nanotechnology‐based therapeutic strategy for breast cancer.