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. 2019 May 15:306:61-65.
doi: 10.1016/j.toxlet.2019.02.011. Epub 2019 Feb 16.

The relative toxicity of brodifacoum enantiomers

Douglas L Feinstein  1 , Kamil Gierzal  2 , Asif Iqbal  3 , Sergey Kalinin  4 , Richard Ripper  5 , Matthew Lindeblad  6 , Alexander Zahkarov  7 , Alexander Lyubimov  8 , Richard van Breemen  9 , Guy Weinberg  10 , Israel Rubinstein  11
Affiliations

The relative toxicity of brodifacoum enantiomers

Douglas L Feinstein et al. Toxicol Lett. .

Abstract

Brodifacoum (BDF) is a potent, long-acting anticoagulant rodenticide that can cause fatal poisoning in humans. The chemical structure of BDF includes 2 chiral carbons, resulting in 2 pairs of diastereomers, BDF-cis (R/S and S/R) and BDF-trans (R/R and S/S). However, the relative potency of these molecules is not known. The purpose of this study was to compare the in vitro and in vivo toxic effects of the 2 BDF diastereomer pairs. In adult Sprague-Dawley rats BDF-cis was significantly more toxic than BDF-trans (LD50 values of 219 versus 316 μg/kg, respectively) while racemic BDF had intermediate potency (266 μg/kg). In adult New Zealand white rabbits, BDF-cis had a longer half-life than BDF-trans which could contribute to its observed increased toxicity. Lastly, BDF-cis (10 μM), but not BDF-trans, damaged cultured SH-SY5Y human neuroblastoma cells by attenuating mitochondrial reductive capacity. Taken together, these data suggest that different toxic manifestations of BDF poisoning in mammals could be attributed, in part, to differences in relative enantiomer concentrations present in racemic formulations of this commercially-available toxicant.

Keywords: Anticoagulation; Brodifacoum; Diastereomer; Enantiomer; Superwarfarins.

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Conflict of interest statement

Declarations

DLF and IR are co-founders of EnSol Therapeutics, LLC. GW is co-founder of ResQ Pharmaceuticals, Inc. All other authors declare that they have no competing financial or non-financial interests.

Figures

Figure 1.
Figure 1.. Chemical structure of BDF and parent compound warfarin
Asterisks indicate the 2 chiral carbons present in BDF
Figure 2.
Figure 2.. Enrichment for BDF enantiomeric pairs.
Racemic BDF (BDF-rac) was separated as described in materials and methods, fractions corresponding to peaks 1 and 2 were collected, and rerun to confirm enrichment. (A) Chromatograph of BDF-rac; (B) Rerun of peak 1 corresponding to BDF-cis; (C) Rerun of peak 2 corresponding to BDF-trans.
Figure 3.
Figure 3.. Dixon plot analysis of acute BDF toxicity
Adult male Sprague Dawley rats (about 300 gm) were administered an i.p. injection (500 μL) to provide the final indicated doses of (A) BDF-rac (n=6 rats), (B) BDF-trans (n=7 rats), or (C) BDF-cis (n=6 rats). The x-axis ‘Test’ indicates each individual test that was done at the indicated BDF concentration. Results of Dixon analysis are shown in the figures, and are mean ± SD. Symbols: o, survived; x, died. *, P < 0.05 versus BDF-cis or BDF-trans; ***, P < 0.0001 versus BDF-trans (1-way ANOVA Tukey’s multiple comparison).
Figure 4.
Figure 4.. Serum half-lives for BDF diastereomers
NZW rabbits (n=8) were given a single administration of racemic BDF (200 μg/kg, by gavage). Blood samples were taken at the indicated times, and serum BDF-cis and –trans levels determined by UHPLC/MS-MS. Total BDF levels were calculated as sum of BDF-cis and BDF-trans (A) Time course of total BDF levels; (B) Time course of BDF-cis (red circles) and BDF-trans (blue circles) levels. Data represent mean ± SE of n=5–8 samples per time point due to deaths occurring during the study (one at day 8; 2 at day 10). The data were fit for one phase decay with plateau set to 0, and the best fit curves are indicated.
Figure 5.
Figure 5.. BDF induces neurotoxicity
The indicated concentrations of BDF or equivalent amount of vehicle were added to human SH-Y-5Y neuroblastoma cells. Immediately after, a time course of mitochondrial reductive capacity was measured by assessment of MTS reduction at the indicated time points. Data are mean ± SE of n=4–6 independent samples. *, P<0.05; **< P<0.005; ***, P<0.0005, 2-way ANOVA and Tukey’s range test.
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References

    1. Ayee MA, Roth CW, Akpa BS, 2016. Structural perturbation of a dipalmitoylphosphatidylcholine (DPPC) bilayer by warfarin and its bolaamphiphilic analogue: A molecular dynamics study. Journal of colloid and interface science 468, 227–237. - PMC - PubMed
    1. Barnette DA, Johnson BP, Pouncey DL, Nshimiyimana R, Desrochers LP, Goodwin TE, Miller GP, 2017. Stereospecific Metabolism of R- and S-Warfarin by Human Hepatic Cytosolic Reductases. Drug metabolism and disposition: the biological fate of chemicals 45, 1000–1007. - PMC - PubMed
    1. Breckenridge A, Orme M, Wesseling H, Lewis RJ, Gibbons R, 1974. Pharmacokinetics and pharmacodynamics of the enantiomers of warfarin in man. Clinical pharmacology and therapeutics 15, 424–430. - PubMed
    1. Connors JM, 2018. Hemorrhagic Highs from Synthetic Cannabinoids - A New Epidemic. The New England journal of medicine 379, 1275–1277. - PubMed
    1. Damin-Pernik M, Espana B, Lefebvre S, Fourel I, Caruel H, Benoit E, Lattard V, 2017. Management of Rodent Populations by Anticoagulant Rodenticides: Toward Third-Generation Anticoagulant Rodenticides. Drug metabolism and disposition: the biological fate of chemicals 45, 160–165. - PubMed

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