In vivo and in silico approaches to assess surface water genotoxicity from Tocantins River, in the cities of Porto Nacional and Palmas, Brazil.

The main environmental problem in urban areas, especially in Brazil, is the discharge of untreated sewage. The in vivo Drosophila melanogaster Somatic Mutation and Recombination Test (SMART) was used to assess the genotoxicity of surface waters from three different sites in the Tocantins River, Brazil. The in silico approach was used to search for known and predicted interactions between environmental chemicals found in our samples and Drosophila and human proteins. The genotoxicity tests were performed in standard (ST) and high bioactivation (HB) crosses with samples collected at two periods, the rainy and dry seasons. Mutant spot frequencies found in treatments with unprocessed water from the test sites were compared with the frequencies observed in negative controls. The collection points were represented as sites A, B and C along Tocantins River. Sites A and B are located in Porto Nacional City, whereas site C is located in Palmas City. Considering the rainy season collection, positive responses in the ST cross were observed for sites A and C (89.47% and 85% of recombination, respectively) and in the HB cross for sites A, B and C (88.24%, 84.21% and 82.35% of recombination, respectively). The positive results in the dry season were restricted to sites A and B (88.89% and 85.71% of recombination, respectively) in the HB cross. In accordance with in vivo and in silico results, we hypothesize that ribosomal proteins (RPs) in fruit fly and humans are depleted in cells exposed to heavy metal causing DNA damage and chromosome instability, increasing homologous recombination.

Genotoxic and chemopreventive assessment of Cynara scolymus L. aqueous extract in a human-derived liver cell line.

Cynara scolymus L., popularly known as artichoke, is consumed as food and used as tea infusions for pharmacological purposes to treat liver dysfunctions and other conditions. Scientific data on the safety and protective effect of artichoke in human-derived liver cells is missing. This study investigated the genotoxic and modulatory effect of a liophilized extract suspended in water of C. scolymus L. leaves. Four extract concentrations (0.62, 1.25, 2.5 and 5.0 mg/mL) were evaluated using the comet assay on human hepatocyte cultures, HepG2 cells. Genotoxicity was assessed after two treatment periods, 1 and 24 h. Antigenotoxicity was evaluated against oxidative lesions induced by hydrogen peroxide in pre-, simultaneous and post-treatment protocols. Artichoke leaves aqueous extract induced genotoxic effects in HepG2 cells after 1- and 24-h treatments. In turn, extract concentrations of 0.62, 1.25 and 2.5 mg/mL, exhibited a protective effect in pretreatment, compared to hydrogen peroxide alone. However, in simultaneous and post-treatment protocols, only the lowest concentration reduced the frequency of DNA damage induced by hydrogen peroxide. In addition, in the simultaneous treatment protocol, the highest artichoke extract concentration increased hydrogen peroxide genotoxicity. It can be concluded that artichoke is genotoxic, in vitro, to HepG2 cells, but can also modulate hydrogen peroxide DNA damage.

Surface Water Impacted by Rural Activities Induces Genetic Toxicity Related to Recombinagenic Events in Vivo.

This investigation assessed the interaction of surface water samples with DNA to quantitatively and qualitatively characterize their mutagenic and/or recombinagenic activity. Samples were obtained at three different sites along the Tocantins River (Tocantins State, Brazil). The area has withstood the impact mainly of rural activities, which release different chemical compounds in the environment. The Drosophila melanogaster Somatic Mutation and Recombination Test (SMART) was performed in standard (ST) and high bioactivation (HB) crosses. SMART is useful for the detection of mutational and recombinational events induced by genotoxins of direct and indirect action. Results demonstrated that samples collected in both seasons were able to induce increments on the mutant spot frequencies in the larvae of the HB cross. Genotoxicity was related to a massive recombinagenic activity. The positive responses ascribed to only the HB cross means that it is linked to pro-genotoxins requiring metabolic activation. The SMART wing test in Drosophila melanogaster was shown to be highly sensitive to detect genotoxic agents present in the aquatic environment impacted by agriculture.