Approved Abstracts

Assessment of toxic effects of a natural dye to aquatic organisms from different trophic levels



Author(s): State University of Campinas - UNICAMP; School of Technology, UNICAMP; School of Technology, UNICAMP; Department of Education/Craft Studies, University of Helsinki; Wilson College of Textiles, NCSU; School of Technology, UNICAMP;
Presenter: Natália Oliveira de Farias

Research on natural resources has increased and biocolorants have been investigated as alternatives to synthetic dyes which can have harmful effects on the environment and ecological balance. Secondary metabolites in fungi offer an interesting source of biobased compounds that could be used as colorants. Natural anthraquinone Dermorubin is extracted from Cortinarius sanguinea and it is being proposed as a biocolorant by the BioColour project. Its natural origin itself does not guarantee the safety of the compound and studies on the toxic effects are necessary. Mutagenicity tests were performed previously and Dermorubin was not mutagenic for five strains (TA98, TA100, TA1537, YG1041 and TA97a) of Salmonella typhimurium tested. In this study, aquatic organisms of three different trophic levels were used to evaluate the toxicity of Dermorubin. Microalgae Pseudokirchneriella subcapitata representing autotrophs, Daphnia similis and Danio rerio representing primary and secondary consumers, respectively. Purified Dermorubin (98%) containing 2% of 5-Cl Dermorubin was obtained from the cited fungi. Tests were conducted in concentration-response experiments with the highest concentration at the limit of solubility. Dimethyl sulfoxide (DMSO) was used to prepare the stock solutions. A chronic toxicity test was performed with the freshwater P. subcapitata according to OECD guideline 201. Algae cells harvested from a liquid stock culture of 3 days old and in a logarithmic phase of growth were used. After 72 h of exposure, growth inhibition was evaluated and the IC50 was determined. Acute toxicity tests with D. similis were performed according to OECD guideline 202. Twenty neonates (<24 h old) from 2- to 3-week-old mothers were placed in 4 replicates for each concentration (5 organisms/replicate). Immobilized organisms were counted after 48 h of exposure and EC50 was determined. For lethal and sub-lethal toxicity assessment a preliminary fish embryotoxicity test was performed according to an extended version of OECD guideline 236. Embryos of D. rerio were exposed to different concentrations of the dye for 168 h. The test was performed in 24-well microplates using 60 eggs per treatment. Embryos and larvae were observed and photographed daily under a stereomicroscope. Mortality and developmental abnormalities were registered. It was not observed significant differences in cell density of microalgae between treatments (0.0625 – 1 mg/L) and the control group. For D. similis the EC50 = 7.7 ± 1.4 mg/L. The dye did not affect the survival of embryos/larvae or caused any other sublethal effect (0.1 – 10 mg/L). Our findings emphasize that the test battery approach of bioassays representing multiple trophic levels is fundamental to assess the hazard effects of natural dyes for aquatic environments. For future studies, more tests will be performed with embryos/larvae of zebrafish to confirm preliminary results and also evaluate its genotoxicity using the Comet assay.
The authors thanks to the “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES)” - Finance Code 001 (NOF: PhD grant), São Paulo Research Foundation – FAPESP project 20/04628-8 and BioColour project.


Keywords: Aquatic toxicity; biocolorant; daphnia

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