Avaliação da atividade antitumoral e toxicidade, em modelo experimental, do lapachol e do L-fucosídeo peracetilado do lapachol (F-LapA) encapsulados em nanoemulsões O/A.

Abstract

Breast cancer is the cancer with the highest incidence among women, accounting for about 30% of new cases in Brazil. Due to its high incidence and lethality, the search for new molecules for an efficient treatment becomes increasingly important. In this context, LAP presents antitumor activity already reported, but limited due to problems of low solubility and adverse effects. Among the alternatives to overcome these challenges, we can mention the search for synthetic analogues of lapachol and the use of nanosystems that can enable its administration. Thus, this work aimed to evaluate the antitumor activity of lapachol and its fucoside derivative encapsulated in nanoemulsions in an animal model of breast cancer. Nanoemulsions were prepared using soybean oil (4.0%), polysorbate 80 (1.4%), glycerol (2.24%) and water (qsp 100%)) containing lapachol or its derivative. The formulations were characterized physicochemically and morphologically, and in vitro release, hemolysis, cell viability and in vivo studies were performed. For the fucoside derivative, analytical validation for dosing was also performed using the standards of RDC 166/2017. The LAP nanoemulsions showed 170 nm size, polydispersity index less than 0.3, zeta potential around -20mV, high encapsulation content with physicochemical stability of at least 30 days. The formulation showed spherical morphology, colloidal stability in biological media for up to 24 hours, cytotoxic activity against breast cancer tumor cells, without significant hemolytic activity. The nanoemulsion radiolabeling showed purity higher than 95%, with increased half-life, high uptake in the tumor region and antitumor activity in an experimental model without signs of toxicity. The analytical validation showed linearity between 2 and 500 µg with R2 greater than 0.99, precision with relative standard deviation less than 5%, detection limit of 0.72 µg and quantification of 2.41 µg with robustness evaluated by changing the suppliers of solvents and equipment. The nanoemulsion containing the fucoside derivative showed size of 180 and 190 nm, evaluated by particle tracking and dynamic light scattering analysis, respectively, polydispersity index less than 0.2, zeta potential at about -20 mV and encapsulation close to 100% when the derivative concentration was 1.5 and 2.0 mg/mL. The physicochemical stability of the nanoemulsion was also evaluated by polarized light microscopy (presence of crystals), was up to 6 and 3 months, respectively. We also obtained a stable formulation in biological media, capable of protecting the derivative from degradation, with approximately three-fold decrease in the mean inhibitory concentration in breast cancer strains and four-fold selectivity compared to healthy strains, and a five-fold increase in the uptake of the encapsulated fucoside derivative compared to the free derivative. Low toxicity was evidenced in the healthy mices studies, while in animal with induced breast tumor there was enhanced antitumor efficacy. Taken together, the results demonstrated that nanoemulsions loaded with lapachol or derivative showed great potential as a more selective treatment platform for breast cancer with reduced adverse effects.