Estudos da toxicidade e do potencial antineoplásico do extrato etanólico de folhas de Petiveria alliacea L.

Abstract

The use of natural resources is an ancient practice, through which man seeks to increase his chance of survival. In this way, primitive man found in the vegetable species many benefits, including the cure for many diseases. Consequently, a number of studies have been developed to ensure the safety and efficacy of medicinal plants, such as the species Petiveria alliacea Lineu., Or guinea, as it is popularly known. In this species, several biological activities have been described, among them, anti-neoplastic activity, which was attributed to polysulfides derived from secondary metabolism. The objective of the present study is to evaluate the antineoplastic, cytotoxic and mutagenic potential of the ethanolic extract of Petiveria alliacea L. Leaf samples were obtained from the Plant Biotechnology Nucleus (NBV) at the State University of Rio de Janeiro (UERJ), where bottled plants are kept, which were collected in private properties of Niterói. The extract was prepared from leaves immersed in ethanol P.A. Human lung carcinoma cells (line A549) were treated with different concentrations of this extract. After the 24-hour treatment period, the cytotoxic activity was analyzed by trypan blue exclusion, WST-1 and clonogenic recovery methods. The dose inhibiting 50% of cell growth was found when cells were exposed to the extract at concentrations of 20 and 25 μg / mL. These concentrations were tested on normal monkey green kidney (VERO) lineage. In this lineage, a 10% decrease in cell viability was observed through the inclusion tests by tripan blue and WST-1. In the clonogenic recovery trial, there was no statistically significant decrease in the mitogenic capacity of the cells when compared to the control. Experiments were carried out to evaluate the rate of production of reactive oxygen species (ROS) by flow cytometry using the DCFH-DA reagent, where the extract was an antioxidant for both tested strains. The other biological model used in this study was yeast S. cerevisiae FF18733 (wild) and CD138 (mutant). Both were evaluated for the fraction of survival, growth, mutagenesis (canavanine resistance system) and petites colonies. The results indicate that the concentration of 10 and 7.5 μg / mL decrease the cell viability in 50% in the strains FF18733 and CD138 respectively. In the growth assay the strains were exposed for 48 h to the P. alliacea extract. No significant decrease was observed in strain FF18733 when compared to the control, since the CD138 strain showed a significant difference in the growth rate. However, in the canavanine resistance test, the extract was mutagenic for both strains. In the experiments to evaluate the loss of mitochondrial function, it was observed that both strains presented an increase in the rate of petites colonies. Analyzing the observed results in yeasts and cell lines, we observed that in both cases a change occurred in the oxidative pathways that affect the mitochondrial metabolism, suggesting that this organelle is more affected by the extract of P. alliacea. It is necessary to study the cell death pathway and the chemical composition of the extract.