Avaliação da atividade citotóxica/antitumoral de extrato hidroalcóolico de própolis

Abstract

Propolis is a natural product produced by bees, coming from the buds and flower buds of various plants to which bees add salivary secretions, wax and pollen, completing its composition. Brown propolis originates from outhern Brazil and has great benefits to human health, due to the content of phenolic compounds found in its composition, important antioxidant substances, preventing damage caused by oxidation. Thus, the aim of the present study was to extract hydroalcoholic compounds from brown propolis and evaluate their cytotoxic activity against normal Macaca mullata kidney cells (LLC-MK2) and human liver tumor cells (HuH7.5), in order to better understand the effect of this propolis. The experimental design to produce the extract, a DCCR (central composite rotational design) 22 with two independent variables (temperature and solvent concentration), showed that the temperature of 80 °C and at a concentration of 90% ethanol and 10% water were the better solid-liquid extraction conditions, in terms of phenolic compounds. The determination of the antioxidant capacity of the hydroalcoholic propolis extract resulted in an EC50 equal to 3.34 ± 0.29 mg mL-1 after 30 minutes of inhibition. The physicochemical analysis of this extract showed that it has an acidic character, with a pH value of 4.77, 15.85% of total acidity, low moisture and total ash, with a percentage of 0.72% and 0.017%, respectively, the percentage of lipids was 4.44%, with a soluble solids value of 21.75°Brix, in addition to not presenting significant values of total sugars. The MTT cytotoxicity test with LLC-MK2 cells did not show a result statistically different from the negative control and, therefore, did not show a cytotoxic effect for the normal renal cells in the present study. As for human hepatocellular carcinoma cells (HuH7.5) the different concentrations (0.25; 0.5; 1.0; 2.5; 5.0; 10; 25; 50; 100 μg mL-1) presented lower mean absorbances and statistically different from the negative control, which indicates a cytotoxic/antiproliferative effect for these tumor cells at times of 24, 48 and 72 hours. Thus, the data from the present study showed that this product deserves to be highlighted in the search for new discoveries to identify better biological activities of the hydroalcoholic extract of brown propolis.