The natural anthraquinone dye emodin: Eco/genotoxicological characterization for aquatic organisms.

Emodin is an anthraquinone secondary metabolite produced by several species of plants and fungi. Emodin is known for its pharmacological versatility, and, in the textile industry, for its good dyeing properties. However, its use in the textile industry can result in the formation and disposal of large volumes of wastewater. Emodin mutagenicity has been shown in bacteria and in human cells, but little is known about its possible toxic, genotoxic, or mutagenic effects in aquatic organisms. We have evaluated the eco/genotoxicity of emodin to aquatic organisms. Emodin was toxic to Daphnia similis (EC50 = 130 µg L-1) and zebrafish embryos (LC50 = 25 µg L-1). No toxicity was observed for Raphidocelis subcapitata, Ceriodaphnia dubia, or Parhyale hawaiensis. Additional biochemistry/molecular studies are needed to elucidate the toxic/mutagenic pathways of emodin in aquatic organisms. The PNEC value for emodin was 0.025 µg L-1. In addition to mutagenicity in the Salmonella/microsome assay, emodin was mutagenic in the micronucleus assay in the amphipod P. hawaiensis. Among the anthraquinone dyes tested to date, natural or synthetic, emodin was the most toxic to aquatic species.

Waterless Dyeing and In Vitro Toxicological Properties of Biocolorants from Cortinarius sanguineus.

As a part of an ongoing interest in identifying environmentally friendly alternatives to synthetic dyes and in using liquid CO2 as a waterless medium for applying the resulting colorants to textiles, our attention turned to yellow-to-red biocolorants produced by Cortinarius sanguineus fungus. The three principal target anthraquinone colorants (emodin, dermocybin, and dermorubin) were isolated from the fungal bodies using a liquid-liquid separation method and characterized using 700 MHz NMR and high-resolution mass spectral analyses. Following structure confirmations, the three colorants were examined for dyeing synthetic polyester (PET) textile fibers in supercritical CO2. We found that all three biocolorants were suitable for dyeing PET fibers using this technology, and our attention then turned to determining their toxicological properties. As emodin has shown mutagenic potential in previous studies, we concentrated our present toxicity studies on dermocybin and dermorubin. Both colorants were non-mutagenic, presented low cellular toxicity, and did not induce skin sensitization. Taken together, our results indicate that dermocybin and dermorubin possess the technical and toxicological properties needed for consideration as synthetic dye alternatives under conditions that are free of wastewater production.

Neuromotor activity inhibition in zebrafish early-life stages after exposure to environmental relevant concentrations of caffeine.

Caffeine (CAF), a neuroactive compound, has been found in surface waters at concentrations ranging from few nanograms up to micrograms and may induce adverse effects in aquatic vertebrates. Thus, the aim of this study was to evaluate the potential of CAF in affecting fish early-life stages in a wide concentration range, including occurring levels in surface waters. Specimens of zebrafish in early-life stages were exposed to CAF for 168 h and survival, developmental alterations, locomotor activity and acetylcholinesterase activity were evaluated. CAF induced mortality in embryos unable to hatch or in larvae after hatching (LC50 - 168 h = 283.2 mg/L). Tail deformities were observed in organisms exposed to concentrations ≥ 40 mg/L, while edemas were found at concentrations of 100 mg/L. CAF also decreased the total swimming time and distance moved of exposed organisms (LOEC = 0.0006 mg/L). Locomotor inhibition may be associated with an acetylcholinesterase inhibition observed at concentration ≥ 0.0088 mg/L. Therefore, the hazard of CAF for fish populations deserves further attention since unexpected effects on neuro-behavioral parameters occurs at concentrations often detected in natural aquatic ecosystems.

Fluoxetine chronic exposure affects growth, behavior and tissue structure of zebrafish.

Fluoxetine (FLX) is among the top 100 pharmaceutical prescribed annually worldwide and consequently is often detected in wastewater treatment plant effluent and surface waters, in concentrations up to 2.7 and 0.33 µg/L, respectively. Despite the presence of FLX in surface waters, little is known about its chronic effects in fish. Thus, this study aimed at investigating the chronic toxicity of FLX to Danio rerio adults. Rate of weight gain, behavior (feeding and swimming activity) and tissue organization (liver and intestine) were evaluated, after 30 days exposure. A lower rate of weight gain was observed at 100 µg/L FLX. The food intake time decreased, showing a decrease in fish appetite. The preference for the upper aquarium layer was observed at 10 and 100 µg/L of FLX, indicating an inhibition of the stress level (anxiolytic effect). Mild to moderate damage of hepatic tissue and a decrease epithelium height and increase in villus height of intestine were observed in fish exposed to concentrations as low as 0.01 µg/L. Based on obtained results, chronic exposure of fish to FLX could affect swimming and feeding behavior and alter morphological structure of liver and intestine tissues at environmental levels.

Exposure to low concentration of fluoxetine affects development, behaviour and acetylcholinesterase activity of zebrafish embryos.

Fluoxetine (FLX) is a selective serotonin reuptake inhibitor (SSRI) antidepressant widely used in clinics and very often found in environmental samples of urban aquatic ecosystems in concentrations ranging from ng/L to µg/L. Fish populations might be especially susceptible to FLX due to the presence of conserved cellular receptors of serotonin. Neurotoxic effects on fish biota of polluted water bodies may be expected, but there are no sufficient studies in the current literature to elucidate this hypothesis. Batteries of embryo larval assays with zebrafish were performed to evaluate the potential effects of FLX exposure, including environmentally relevant concentrations. Evaluated parameters included survival, development, behaviour and neuronal biochemical markers. Regarding acute toxicity, a 168 h-LC50 value of 1.18 mg/L was obtained. Moreover, hatching delay and loss of equilibrium were observed, but at a concentration level much higher than FLX measured environmental concentrations (>100 µg/L). On the other hand, effects on locomotor and acetylcholinesterase activity (≥0.88 and 6 µg/L, respectively) were found at levels close to the maximum reported FLX concentration in surface waters. Altogether, these results suggest that FLX is neurotoxic to early life stages of zebrafish, in a short period of time causing changes in important ecological attributes which can probably be linked from molecular to population level.