Sintese, caracterização e avaliação da atividade antitumoral in vitro de uma nanocápsula contendo óleo de copaiba (Copaifera sp.) Em células de adenocarcinoma mamário humano

Abstract

Breast cancer is one of the most prevalent neoplastic types in Brazil and worldwide, with limited treatment options due to tumor resistance and/or the toxicity of available therapies. In this context, natural products and their derivatives have been investigated as promising sources for new compounds with antineoplastic activity. Copaiba oil (CO), a potent natural derivative extracted from the trunk of trees of the Copaifera genus, exhibits anticancer activity. However, its use can be limited due to its high volatility and lipophilicity. Polymeric nanocapsules are compound delivery systems that can offer benefits, such as improved stability for the bioactive compound, increased penetration into tumor cells, and, consequently, enhanced pharmacological activity. Thus, the aim of this study was to develop, characterize, and evaluate the antitumor activity of a polymeric nanoparticle in the form of a nanocapsule containing copaiba oil (NPOC) in breast adenocarcinoma cell lines. To achieve this, a pre-formulation study of NPOC was conducted, followed by morphological and physicochemical characterizations, as well as stability and cellular internalization studies. NPOC (containing 40 µg/mL of CO) demonstrated the desired parameters for a nanoparticle and was able to penetrate breast cancer cells (MCF-7). When tested on breast cancer cell lines such as MCF-7 and MDA-MB-231, NPOC exhibited cytotoxicity (IC50 of 25 ± 0.83 and 31 ± 0.75 µg/mL, respectively), with superior activity compared to isolated CO at the same concentrations (IC50 of 49 ± 2.1 and 63 ± 1.86 µg/mL, respectively). Additionally, in non-tumoral cell lines MCF-10A and HEK-293, it showed reduced toxicity, being more selective than CO and the standard drug doxorubicin (DXR). The MCF-7 cell line, due to its greater sensitivity in cytotoxicity studies, was selected for subsequent experiments. In cell death type studies with acridine orange/propidium iodide (AO/PI) and Hoechst 34580, NPOC was shown to induce apoptosis, leading the cells to exhibit characteristics such as membrane bleb formation and nuclear alterations, with results superior to CO. In mitochondrial alteration studies using JC-1, a loss of mitochondrial membrane potential was observed, indicating an intrinsic apoptosis pathway induced by NPOC and CO, with a more pronounced response in the nanocarrier treatment. In studies on the cellular redox state, pre-treatment with N-Acetylcysteine (NAC) revealed that both NPOC and CO induce oxidative stress, suggesting a possible cytotoxic mechanism. Furthermore, cytotoxicity experiments using 3D spheroid culture demonstrated that NPOC was effective in reducing microtumor size (82.6% at IC50) and decreasing cell migration radius (88% at IC50), outperforming CO. Thus, it is concluded that NPOC presents a significant improvement in antitumor activity compared to CO, with high selectivity toward breast cancer cells through mechanisms involving apoptosis and oxidative stress pathways.