Cytotoxic and Genotoxic Effects of Cyanobacterial and Algal Extracts-Microcystin and Retinoic Acid Content.

Michal Bittner,Klára Hilscherová,Marie Smutná,Bojana Žegura,Alja Štern

doi:10.3390/toxins13020107

Michal Bittner, Klára Hilscherová + Show 3 more

Open Access

https://doi.org/10.3390/toxins13020107

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Journal: Toxins	Publication Date: Feb 2, 2021
Citations: 17	License type: CC BY 4.0

Affiliation: Masaryk University, National Institute of Biology

Abstract

In the last decade, it has become evident that complex mixtures of cyanobacterial bioactive substances, simultaneously present in blooms, often exert adverse effects that are different from those of pure cyanotoxins, and awareness has been raised on the importance of studying complex mixtures and chemical interactions. We aimed to investigate cytotoxic and genotoxic effects of complex extracts from laboratory cultures of cyanobacterial species from different orders (Cylindrospermopsis raciborskii, Aphanizomenon gracile, Microcystis aeruginosa, M. viridis, M. ichtyoblabe, Planktothrix agardhii, Limnothrix redekei) and algae (Desmodesmus quadricauda), and examine possible relationships between the observed effects and toxin and retinoic acid (RA) content in the extracts. The cytotoxic and genotoxic effects of the extracts were studied in the human hepatocellular carcinoma HepG2 cell line, using the MTT assay, and the comet and cytokinesis-block micronucleus (cytome) assays, respectively. Liquid chromatography electrospray ionization mass spectrometry (LC/ESI-MS) was used to detect toxins (microcystins (MC-LR, MC-RR, MC-YR) and cylindrospermopsin) and RAs (ATRA and 9cis-RA) in the extracts. Six out of eight extracts were cytotoxic (0.04–2 mgDM/mL), and five induced DNA strand breaks at non-cytotoxic concentrations (0.2–2 mgDM/mL). The extracts with genotoxic activity also had the highest content of RAs and there was a linear association between RA content and genotoxicity, indicating their possible involvement; however further research is needed to identify and confirm the compounds involved and to elucidate possible genotoxic effects of RAs.

Highlights

Eutrophication is nowadays pervasive in numerous lakes, rivers, and water reservoirs around the world due to anthropogenic input of nutrients, which create favorable conditions for cyanobacterial and algal mass development [1,2]
Cyanobacteria and algae produce a vast diversity of bioactive compounds that can be simultaneously present in the environment
It is important to characterize the toxic effects of complex mixtures as these can differ substantially from those induced by pure compounds

Summary

Introduction

Eutrophication is nowadays pervasive in numerous lakes, rivers, and water reservoirs around the world due to anthropogenic input of nutrients, which create favorable conditions for cyanobacterial and algal mass development [1,2]. There is evidence that certain cyanotoxins are genotoxic and potentially carcinogenic; the mechanisms behind their genotoxic activity are still not completely understood (for review see: [2,4,10]). MCs induce genotoxic effects indirectly, primarily through the formation of reactive oxygen species, resulting in oxidative stress and oxidative DNA damage (for review see: [12]). The toxin was reported to be genotoxic in various test systems and is potentially carcinogenic, and there is strong evidence that it needs metabolic activation by cytochrome P450 enzymes in order to cause DNA damage and to exert genomic instability (for review, see [10,16])

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