Mutation Research/Genetic Toxicology and Environmental Mutagenesis
In vitro and in vivo genotoxicity assessment of ferric ferrocyanide and potassium-cobalt ferrocyanide
Introduction
Ferric hexacyanoferrate(II), known as Prussian blue (PB), has the empirical formula Fe4[Fe(CN)6]3. It was probably synthesized for the first time by the paint maker Diesbach in Berlin in 1704, and it was one of the first synthetic pigments. Prussian blue is available as Radiogardase® in Germany and France. The use of Prussian blue against thallium poisoning and as a decorporation agent for 134cesium and 137cesium has been investigated since the 1960s. It was recommended in the treatment of thallium intoxication in the 1970s and it is now normally used. The disaster at the Chernobyl nuclear reactor in 1986 led to further studies on the elimination of radioactive cesium. In 1987, following Goiania accident in Brazil, Prussian blue was used in the management of a large scale radiation disaster [1]. It is used as an orally ingested drug to enhance the excretion of isotopes of cesium and thallium from the body by means of ion exchange: thallium ions are excreted into the intestine and reabsorbed mainly in the colon into blood to be excreted again into the intestinal tract while cesium is excreted into the intestinal tract in the bile to be reabsorbed into portal blood and transported to the liver to again be excreted via bile (enterohepatic circulation). Therefore, orally administered Prussian blue is able to take over these two toxic metal ions in the intestine, stopping the reabsorption from the gastrointestinal tract and favoring their fecal excretion. Prussian blue is not intestinally absorbed in significant amounts, and can be considered safe and effective for the treatment of internal contamination with radioactive or nonradioactive thallium, and with radioactive cesium.
Potassium cobalt hexacyanoferrate(II), formula K2COFe(CN)6, has also been investigated as a cesium decontamination agent. In vivo, on rats, this compound proved to be at least as efficient as PB and even more efficient according some studies [2] to enhance the excretion of isotopes of cesium from the body. This result, associated with a total insolubility, meaning no absorption in gastrointestinal tract, made Potassium cobalt hexacyanoferrate(II) suitable for a potential clinical use.
To investigate the opportunity of further preclinical and clinical development of this compound, it was then necessary to assess its genotoxicity profile and to compare it with the reference clinical standard PB. For this, the bacterial reverse mutation assay (Ames test), the mutation assay at the TK locus in L5178Y mouse lymphoma cells and the in vitro chromosomal aberrations test on peripheral blood lymphocytes were carried out. Moreover, the in vitro Unscheduled DNA Synthesis (UDS) assay was performed with potassium-cobalt ferrocyanide salts. Furthermore, the in vivo mouse bone marrow micronucleus test and the Comet Assay in rat were implemented for Ferric ferrocyanide exclusively.
Section snippets
Reagents and chemicals
The reagents and chemicals used in the experiments were purchased from the following suppliers: Dimethylsulfoxide from Acros Organics, Noisy le Grand, France; normal melting point agarose, low melting point agarose from Biorad, Marnes la Coquette, France; RPMI 1640 medium, horse serum, fetal calf serum, phosphate buffered saline from GIBCO Invitrogen SARL, Cergy-Pontoise, France; sterile water from Fresenius, Bad Homburg, Germany; HCl, L-glutamine, tryptophan, NaOH, Na2HPO4, Na H2PO4, H2O,
Bacterial reverse mutation assay (Ames test)
Results of the second main assay carried out with the more sensitive pre-incubation protocol in presence of metabolic activation are summarized in Table 1 for K-Co-ferrocyanide and in Table 2 for Fe-ferrocyanide.
In two independent assays in absence and in presence of S9-mix, no significant increase in the mean number of revertants was observed in the 5 Salmonella typhimurium strains TA1535, TA1537, TA98, TA100 and TA102 in the presence of either K-Co-ferrocyanide or Fe-ferderrocyanide.
In these
Discussion/conclusion
In vivo, on rats, Potassium cobalt hexacyanoferrate(II) proved to be at least as efficient as PB and even more efficient according to some studies, to enhance the excretion of isotopes of cesium from the body [2]. This result, associated with a total insolubility meaning no absorption in gastrointestinal tract, made potassium cobalt hexacyanoferrate(II) suitable for a potential use in Human. To test the opportunity of a further preclinical and clinical development of this compound, it was then
Declaration of Competing Interest
These studies were funded by Pharmacie centrale des armées.
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