[Cr3O(O2CCH2CH3)6(H2O)3]+ (Cr3) toxicity potential in bacterial and mammalian cells

Abstract

Chromium(III) has generally been considered to be essential for proper carbohydrate and lipid metabolism, and despite recent evidence to the contrary, chromium(III)-containing compounds remain one of the most popular commercial dietary supplements. Cr3, or [Cr3O(O2CCH2CH3)6(H2O)3]+, is a trivalent chromium compound that is a promising chromium nutritional supplement. Studies with Cr3 have indicated that it is nontoxic in developmental and short- and long-term exposures studies in rodents, but the safety of this compound to chromosomes and cells has not been explored. The current study evaluates the mutagenicity, cytotoxicity, and clastogenicity of Cr3 in bacterial and mammalian cells. Mutagenicity was tested in Escherichia coli FX-11 after treatment with Cr3 or chromium picolinate (CrPic) from 0.025 mM to 1.0 mM for 1 h/48 h. Salmonella typhimurium (TA 98 and TA 100) were also tested for mutagenicity after treatment with Cr3 or CrPic up to 10,000 μg/plate with and without S9 metabolism. Cytotoxicity was measured as a decrease in plating efficiency relative to controls after treatment with 4.0 μg/cm2, 20 μg/cm2, 40 ug/cm2, and 80 μg/cm2 of Cr3 and CrPic for 24 h in CHO K1 cells. Clastogenicity was measured by counting the number of metaphases damaged and of the total number chromosomal aberrations in CHO K1 cells. Mutagenesis assays in E. coli and S. typhimurium were negative both with and without S9 mixture. All treatments of Cr3 produced ≥ 84％ plating efficiency except 80 μg/cm2, which reduced the plating efficiency to 62%. Cr3 at the above treatments did not produce a significant increase in the number of cells with abnormal metaphases, while treatments ≥ 40 μg/cm2 of CrPic elevated the number significantly. These data suggest that Cr3 is neither mutagenic in bacteria cells nor clastogenic in CHO K1 cells.