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Open access

Bojan Sedmak, Tina Eleršek, Olga Grach-Pogrebinsky, Shmuel Carmeli, Nataša Sever and Tamara Lah

Ecotoxicologically relevant cyclic peptides from cyanobacterial bloom (Planktothrix rubescens) - a threat to human and environmental health

Background. The information of the overall production of major cyanobacterial cyclic peptides in a water body is essential for risk assessment and for the prediction of future development of the bloom. A procedure that gives a review of both toxic and non-hepatotoxic hydrophilic cyclic peptide production is important to evaluate the ecological conditions in the water environment and to predict the release of dangerous toxic and tumour promoting substances.

Methods. The cyclic peptides were identified on the basis of their retention times, characteristic spectra, molecular masses and biological activity. The non-hepatotoxic cyclic peptides were characterised by their inhibition of porcine pancreatic elastase, while cytotoxicity to mammalian cells was tested with the MTT test on B16 cell line.

Conclusions. The method presented gives a rapid, simultaneous assessment, preliminary identification and estimation of bioactive cyclic peptides. The synthesis of non-hepatotoxic cyclic peptides can mediate the release various toxic and otherwise biologically active substances that induce systemic genotoxicity in mammals.

Open access

Metka Filipič, Bojana Žegura, Bojan Sedmak, Irena Horvat-Žnidaršic, Aleksandra Milutinovič and Dušan Šuput

Subchronic exposure of rats to sublethal dose of microcystin-YR induces DNA damage in multiple organs

Background. Microcystins (MCs) are cyclic heptapeptides that are considered to be liver specific toxins. They are potent tumour promoters and recent studies indicate that they are also genotoxic. In this study we measured DNA damage in lymphocytes, liver, kidney (cortex and medulla), lung, spleen and brain cells of male Fisher F344 rats that were exposed to sublethal dose (every second day 10 μg/kg b.w.; i.p) of micro-cystin-YR (MCYR) for one month.

Methods. At the end of exposure the animals were sacrificed, the lymphocytes were isolated from blood taken from jugular vein, liver cells were obtained by perfusion with collagenase A and the cells from other organs were isolated by incubating small tissue pieces with collagenase A. The DNA damage in isolated cells was measured with the single cells gel electrophoresis (SCGE) also called the comet assay.

Results. A significant increase of the % tail DNA in MCYR-exposed animals compared to the nonexposed control ones was observed in brain (2.5 fold), liver (2.1 fold), kidney medulla (1.9 fold), kidney cortex (1.8 fold) and lung (1.7 fold) cells, while the DNA from lymphocytes and spleen cells was not affected.

Conclusion. This study demonstrated that subchronic exposure to sublethal doses of MCs can induce systemic genotoxicity in mammals, and it affects not only the liver but also other vital organs.