Ecotoxicity and genotoxicity assessment of losartan after UV/H2O2 and UVC/photolysis treatments.

Losartan potassium (LOS) is one of the most antihypertensives used in the world, and its presence in environmental matrices can cause impacts to biota. In this study, the ecotoxicity and genotoxicity of LOS was assessed before and after treatment by UVC/photolysis and UV/H2O2. The photodegradations were carried out at LOS solutions (2.5 mg L-1; 4.6 µM) for 30, 60, 90, 120, 240, and 480 min of treatment. For chromatographic analysis, the samples were submitted to solid-phase extraction (SPE) and analyzed by HPLC-DAD. Ecotoxicity bioassays were conducted using Daphnia magna (acute) and Desmodesmus subspicatus (chronic) for all the degradation times. To evaluate the genotoxicity, the comet assay was performed with a D. magna whole organism cell suspension applying the alkaline gel electrophoresis technique. For both process, the degradation rate was over 99% at 30 min, which reduced the acute toxicity of LOS to D. magna. In addition, only the sample treated at 240 min by UV/H2O2 showed significant chronic and acute toxicity. However, the genotoxicity effect was observed for samples treated LOS before treatment and at 480 min by UV/H2O2. Therefore, even reaching high LOS degradation rates, for both processes, the bioassays demonstrated the importance of ecotoxicological analyses by AOPs treatment.

Ecotoxicity response of chlorpyrifos in Aedes aegypti larvae and Lactuca sativa seeds after UV/H2O2 and UVC oxidation.

Chlorpyrifos (CP) is an organophosphate pesticide widely used in agriculture known to cause neurological and immunological effects in addition to interfering in the reproduction and development of organisms. In this study, CP degradation by UV/H2O2 process and UVC radiation was investigated, and the ecotoxicity and phytotoxicity was evaluated using bioassays of Aedes aegypti larvae and Lactuca sativa seeds. CP degradation was monitored by HPLC-DAD, and kinetic parameters were calculated for all processes evaluated. Results demonstrated that both processes are efficient, showing a reduction of over 97% of initial CP after 20 and 60 min of UV/H2O2 and UVC radiation, respectively. However, samples treated by UV/H2O2 process demonstrated increase of toxicity, leading to larvae mortality (>90% of organisms) and inhibition effects in seed root growth. The relationship between increased toxicity and the CP byproducts formed was not confirmed due to its low concentration. However, the direct influence of acetonitrile solvent, specifically their toxic byproducts, was observed. This study provides insights into parent compound abatement using oxidative treatment and the changes in toxicity due to the transformation of CP byproducts and complex mixtures (acetonitrile as solvent and hydrogen peroxide).

Saxitoxins induce cytotoxicity, genotoxicity and oxidative stress in teleost neurons in vitro.

The aim of this study was establish a protocol for isolation and primary culture of neurons from tropical freshwater fish species Hoplias malabaricus for assessment of the effects of neurotoxic substances as saxitoxins (STXs). Cells from brain of H. malabaricus were treated with different concentrations of trypsin, dispase and papain for tissue dissociation. Cells type was separated by cellular gradient and basic fibroblast growth factor (bFGF) supplement nutrition media were added. The dissociated cells were plated with medium and different STXs concentrations and the toxic cellular effects such as oxidative stress, neurotoxicity, and genotoxicity and apoptosis process were evaluated. Cultures treated with bFGF showed the greatest adherence, survival and cellular development. STXs increased specific activity of glutathione peroxidase and lipoperoxidation levels, were cytotoxic and genotoxic indicated by the comet assay. Although the STXs effects due the blockage of sodium channels is reported to be reversible, the time exposure and concentration of STXs suggested cellular injuries which can lead to neuropathology. The establishment of primary neuronal culture protocol enables new applications for neurotoxicological assessments.

First report about saxitoxins in freshwater fish Hoplias malabaricus through trophic exposure.

Cyanobacterial waterblooms, such as the saxitoxin (STX) producer Cylindrospermopsis raciborskii, have been a worldwide concern in environmental health. However, the bioaccumulation of this neurotoxin in the trophic chain is not completely known. The aim of the present work was to evaluate STX bioaccumulation through chemical analyses and the toxic and trophic effects using biomarkers in the tropical freshwater fish Hoplias malabaricus. They were fed once every five days with Astyanax sp. before being subjected to intraperitoneal inoculation with STX extract (0.08 µg/100 g) obtained by lysis of toxic C. raciborskii strain (T3). After 20 days the brain was collected for acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione (GSH), lipoperoxidation (LPO), protein carbonylation (PCO), and comet assay analysis. The muscle was collected for STX chemical analysis. The activities of SOD and concentrations of PCO and LPO increased. The CAT, GST, and GPx activities decreased. Genotoxicity was observed in the experimental group. STX was not detected in muscle samples. Thus, an oxidative stress was observed in the brain, leading to the damage of lipids, proteins, and DNA. The mechanism of action of the neurotoxin in this subchronic exposure suggests an apoptotic cellular process.

Analyses of paralytic shellfish toxins and biomarkers in a southern Brazilian reservoir.

The Alagados Reservoir (Brazil) is an important source for the supply of water, recreation and fishery. Since 2002, the occurrence of cyanobacterial blooms (paralytic shellfish toxins - PST producers) have been noted. This study was aimed at the monitoring of PST occurrence in the Reservoir's water and fish. Biomarkers such as ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), catalase (CAT), and acetylcholinesterase (AchE) activities, lipoperoxidation (LPO), histopathology, and comet assay were analyzed in fish. Water and fish were sampled in spring, summer and autumn. The PST concentrations in water were 5.15, 43.84, and 50.78 ng equiv Saxitoxin/L in the spring, summer and autumn, respectively. The PST muscle concentration was below the limit for shellfish. Gonyautoxins (GTX) were found in water samples and fish muscle, and GTX 5 was the major analogous found in muscle. In the summer samples, the LPO, genetic damage, and the GST and AchE activities increased while in the autumn an increase in EROD activity and genetic damage were observed. In all samplings, histopathological alterations in the fish gills and liver were found. The results showed a seasonal variation in the fishes health, which could be related also to farming activities and to the contaminants bioavailability during the year.

Establishment of experimental conditions for preserving samples of fish blood for analysis with both comet assay and flow cytometry.

When environmental analysis is performed, the high number of samples required and handling conditions during the transport of these samples to the laboratory are common problems. The comet assay is a useful, highly sensitive tool in biomonitoring. Some studies in the literature aim to preserve slides in lysis solution for use in the comet assay. Until now, however, no efficient methodology for preserving blood samples for this assay has been described. Because of this, the present report aimed to establish the proper conditions for samples maintenance prior to comet assay analysis. Samples were conserved in three different solutions: a high protein concentration solution (fetal bovine serum-FBS), an anticoagulant agent (a calcium chelator - ethylenediaminetetracetic acid - EDTA), and a salt buffered solution (phosphate buffered saline-PBS). Therefore, peripheral blood samples of Rhamdia quelen specimens were collected and maintained in these solutions until testing at 72h. Analyses of DNA fragmentation via the comet assay and cell viability via flow cytometry were performed at intervals of 24h. The results showed that samples maintained in FBS were preserved better; this was followed by those preserved in PBS and then last by those preserved in EDTA. In conclusion, blood samples from freshwater fish can be preserved up to 48h in fetal bovine serum at 4 degrees C in the absence of light. In this period, no DNA fragmentation occurs. We thus describe an excellent method of sample conservation for subsequent analysis in the laboratory.