engleski

Ecotoxicological Effects of Methylnitrocatechols

Nitrated monoaromatic compounds (NACs) are considered as indicators of secondary organic aerosols in the atmosphere mainly formed from biomass burning (BB) and anthropogenic sources [1]. MNCs are compounds determined in high concentrations in ambient particles contributing (with other less represented NACs) ~ 1% to their total organic mass [2]. These compounds are atmospheric pollutants that can easily enter aquatic ecosystems through atmospheric deposition [3]. We investigated the ecotoxicological effects of the selected model methylnitrocatechols (MNCs) 3- methyl-4-nitrocatechol (3M4NC), 3-methyl-5- nitrocatechol (3M5NC) and 4-methyl-5-nitrocatechol (4M5NC) as well as their mixtures. Acute and chronic toxicity was determined by measuring the cytotoxic effect in vitro on PLHC1 fish cells (MTT test) and chronic toxicity was determined in vivo by measuring the growth inhibition of unicellular green algae of the species Scenedesmus subspicatus (AlgalTox) over a 96-hour period. In vitro bioassays were performed to determine the interaction with phases 0 and I of cellular detoxification mechanism. The inhibition of phase 0 membrane transporters, organic cation transporter Oct1 and organic anion transporting polypeptide Oatp1d1 was determined using Flp-In- 293-drOct1 and Flp-In-293- drOatp1d1 stable cell lines. The results of measuring the inhibition of Oct1 transport of ASP+ model substrate after simultaneous incubation with model compounds showed inhibitory effect on model substrate uptake. Individual compounds and their mixtures inhibited in the range of 23.9 - 43.2 uM. We determined the inhibition of the transport activity of Oatp1d1 by measuring the inhibition of the uptake of the model substrate lucifer yellow (LY) after simultaneous incubation with model compounds. Individual compounds and their mixtures inhibited in the range of 28.8 – 53.6 uM. Phase I induction of CYP1A1 detoxification enzymes by EROD bioassay revealed that neither the model MNCs nor their mixtures were typical inducers of the CYP1A1 enzyme. The observed significant toxic effects of individual MNCs and their mixtures will be discussed in the view of their structure and in relation to their concentrations found in aerosol samples affected by BB and mixed antropogenic sources. Acknowledgements This research was financed by the Croatian Science Foundation project BiREADI (IP-2018-01-3105) We also acknowledge financial support from Marie Curie FP7-PEOPLE-2011-COFUND (GA No. 291823) through the NEWFELPRO project AERONAR (Contract No. 47).

atmospheric pollutants ; acute toxicity ; chronic toxicity ; cellular detoxification mechanism

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