Preparation, analysis and toxicity characterisation of the redox metabolites of the azo food dye tartrazine

Tartrazine (E102, FD&C Yellow 5) is a vibrant yellow azo dye added to many processed foods. The safety of this ubiquitous chemical has not been fully elucidated, and it has been linked to allergic reactions and ADHD in some individuals. In our study, bacterial species isolated from human stool decolourised tartrazine and, upon exposure to air, a purple compound formed. Tartrazine is known to undergo reduction in the gut to sulfanilic acid and 4-amino-3-carboxy-5-hydroxy-1-(4-sulfophenyl)pyrazole (SCAP). These metabolites and their derivatives are relevant to the toxicology of tartrazine. The toxicity of sulfanilic acid has been studied before, but the oxidative instability of SCAP has previously prevented full characterisation. We have verified the chemical identity of SCAP and confirmed that the purple-coloured oxidation derivative is 4-(3-carboxy-5-hydroxy-1-(4-sulfophenyl)-1H-pyrazol-4-yl)imino-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid (purpurazoic acid, PPA), as proposed by Westöö in 1965. A yellow derivative of SCAP is proposed to be the hydrolysed oxidation product, 4,5-dioxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid. SCAP and PPA are moderately toxic to human cells (IC50 89 and 78 μM against HEK-293, respectively), but had no apparent effect on Escherichia coli and Bacillus subtilis bacteria. These results prompt further analyses of the toxicology of tartrazine and its derivatives.

Perinatal Exposure to Tartrazine Triggers Oxidative Stress and Neurobehavioral Alterations in Mice Offspring

The use of synthetic azo dyes as coloring agents in food products has dramatically increased. This study evaluated the effect of perinatal exposure to tartrazine (TZ) on mice offspring, focusing on neurobehavioral alterations and oxidative stress. The female mice received TZ (2.5 and 5 mg/kg) via oral gavage during pregnancy and the first 15 days after birth. At days 21 and 35 after birth, male mice were sacrificed, and samples were collected for analyses. Perinatal exposure to TZ triggered tissue injury evidenced by the histological alterations and neuronal damage in the cerebrum, medulla oblongata, and cerebellum. TZ provoked lipid peroxidation and diminished cellular antioxidants in different brain regions of the newborns. In addition, TZ increased hemoglobin content, as well as erythrocytes, leukocytes, and platelets count at days 21 and 35 after birth. Both the locomotor behavior and anxiety reflex were significantly altered in mice exposed to TZ. In conclusion, perinatal exposure to TZ within an adequate daily intake range induced oxidative stress and neurobehavioral and hematological alterations in mice offspring. Therefore, consuming foods containing TZ during pregnancy and lactation warrants public awareness.

Lack of genotoxicity in vivo for food color additive Tartrazine

Tartrazine is approved as a food color additive internationally with INS number 102, in the United States as food color subject to batch certification "Food, Drug, and Cosmetic" (FD&C) Yellow No. 5, and in Europe as food color additive with E number 102. In their evaluation of the color (2013), the European Food Safety Authority (EFSA) expressed concerns of potential genotoxicity, based primarily on one genotoxicity study that was not conducted according to Guidelines. The present in vivo genotoxicity study was conducted according to OECD Guidelines in response to EFSA's request for additional data. The animal species and strain, and the tissues examined were selected specifically to address the previously reported findings. The results of this study show clear absence of genotoxic activity for Tartrazine, in the bone marrow micronucleus assay and the Comet assay in the liver, stomach, and colon. These data addressed EFSA's concerns for genotoxicity. The Joint WHO/FAO Committee on Food Additives (JECFA) (2016) also reviewed these data and concluded that there is no genotoxicity concern for Tartrazine. Negative findings in parallel genotoxicity studies on Allura Red AC and Ponceau 4R (published separately) are consistent with lack of genotoxicity for azo dyes used as food colors.