Estudo dos potenciais antitumoral e mutagênico das frações do extrato foliar de Hovenia dulcis Thunberg (Rhamnaceae)

Abstract

The use of plants is an ancient way of treating diseases, adopted by practically all people in the world. Hovenia dulcis Thunberg is popularly known as Japanese grape, occurring naturally in China, Japan and the Koreas. The species, found in southern and southeastern Brazil, has important biological activities, highlighting its anti-inflammatory, hepatoprotective, hypoglycemic and antineoplastic activities on various cell types. This work aimed to study response pathways related to antioxidant, mutagenic, antitumor and anti-inflammatory potentials against the ethanol extract fractions of H. dulcis leaves, indicating the pharmacologically active components. In this work, leaf extracts were prepared in 95% ethanol and subsequently partitioned using increasing polarity solvents (hexane, dichloromethane, ethyl acetate and butanol). Saccharomyces cerevisiae FF18733 (wild) and CD138 (mutant) strains were used as biological models in this study. Both were evaluated for cell inactivation, growth inhibition and mutagenesis (canavanin resistance assay) and petite colonies. The results show that, after treatment with the extract fractions, there was a 50% decrease in cell viability in both strains. In the growth assay, the strains were exposed for 48 hours to the H. dulcis extract fractions. A statistically significant decrease was observed in both strains when compared to 1% DMSO control. However, in the canavanin resistance assay, the H. dulcis extract was shown to be mutagenic for the mutant strain (CD138). In experiments to assess the loss of mitochondrial function, it was observed that the ethyl acetate and butanol fractions showed an increase in the rate of petite colonies in the mutant strain (CD138). In the assay to evaluate the antitumor activity, human lung carcinoma cells (A549) were treated with different concentrations of the ethyl acetate and butanol fraction, the most toxic for Saccharomyces cerevisiae. After the 24-hour treatment period, cytotoxic activity was analyzed by WST-1 and clonogenic recovery methods. The dose that inhibited 50% of cell growth was verified when the cells were exposed to the extract at a concentration of 75 and 150 μg/mL, respectively. These concentrations were tested in the normal green monkey kidney lineage (Vero). In this strain, a decrease in cell viability was also observed through the WST-1 assay, this decrease being significantly lower when compared to the tumor strain. In the clonogenic recovery assay, a statistically significant decrease was observed in the mitogenic capacity of cells when compared to DMSO1% control only in the A549 lineage, when treated with ethyl acetate and butanol fractions. The studies indicate a mutagenic potential for the first time reported for the species, which denotes caution with the unsafeuse of its products. But also show that H. dulcis has characteristics of an agent with antitumor activity.