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

Ruth Pay; Abigail V. Sharrock; Riley Elder; Alaigne Marie; Joe Bracegirdle; Dan Torres; Niall Malone; Jan Vorster; Libusha Kelly; Ali Ryan; P. David Josephy; Emma Allen-Vercoe; David F. Ackerley; Robert A. Keyzers; Joanne E. Harvey

doi:10.1016/j.fct.2023.114193

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

Ruth Pay, Abigail V. Sharrock, Riley Elder, Alaigne Marie, Joe Bracegirdle, Dan Torres, Niall Malone, Jan Vorster, Libusha Kelly, Ali Ryan, P. David Josephy, Emma Allen-Vercoe, David F. Ackerley, Robert A. Keyzers, Joanne E. Harvey^*

^*Corresponding author for this work

Applied Sciences Department

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

110 Downloads (Pure)

Abstract

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. Both 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.

Original language	English
Article number	114193
Number of pages	9
Journal	Food and Chemical Toxicology
Volume	182
Early online date	18 Nov 2023
DOIs	https://doi.org/10.1016/j.fct.2023.114193
Publication status	Published - 1 Dec 2023

Keywords

Azo dye
Tartrazine
FD&C yellow 5
E102
C.I. 19140
Metabolite
4-Amino-3-carboxy-5-hydroxy-1-(4-sulfophenyl)pyrazole
SCAP
Gut microbiome
Cell toxicity

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1-s2.0-S0278691523005951-mainAccepted author manuscript, 1.38 MBLicence: CC BY
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Cite this

Pay, R., Sharrock, A. V., Elder, R., Marie, A., Bracegirdle, J., Torres, D., Malone, N., Vorster, J., Kelly, L., Ryan, A., Josephy, P. D., Allen-Vercoe, E., Ackerley, D. F., Keyzers, R. A., & Harvey, J. E. (2023). Preparation, analysis and toxicity characterisation of the redox metabolites of the azo food dye tartrazine. Food and Chemical Toxicology, 182, Article 114193. https://doi.org/10.1016/j.fct.2023.114193

@article{1b4e8cb611f844e38c4d326504abeeec,

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

abstract = "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 West{\"o}{\"o} 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. Both 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.",

keywords = "Azo dye, Tartrazine, FD&C yellow 5, E102, C.I. 19140, Metabolite, 4-Amino-3-carboxy-5-hydroxy-1-(4-sulfophenyl)pyrazole, SCAP, Gut microbiome, Cell toxicity",

author = "Ruth Pay and Sharrock, {Abigail V.} and Riley Elder and Alaigne Marie and Joe Bracegirdle and Dan Torres and Niall Malone and Jan Vorster and Libusha Kelly and Ali Ryan and Josephy, {P. David} and Emma Allen-Vercoe and Ackerley, {David F.} and Keyzers, {Robert A.} and Harvey, {Joanne E.}",

note = "Funding information: We are grateful to Te Apārangi Royal Society of New Zealand for a Catalyst Seeding Grant (20-VUW011-CSG), to the Wellington Medical Research Foundation for providing Research for Life Fellowship funding (Dr Abigail Sharrock), and to Victoria University of Wellington for PhD (Joe Bracegirdle) and summer (Ruth Pay) scholarships.",

year = "2023",

month = dec,

day = "1",

doi = "10.1016/j.fct.2023.114193",

language = "English",

volume = "182",

journal = "Food and Chemical Toxicology",

issn = "0278-6915",

publisher = "Elsevier",

}

Pay, R, Sharrock, AV, Elder, R, Marie, A, Bracegirdle, J, Torres, D, Malone, N, Vorster, J, Kelly, L, Ryan, A, Josephy, PD, Allen-Vercoe, E, Ackerley, DF, Keyzers, RA & Harvey, JE 2023, 'Preparation, analysis and toxicity characterisation of the redox metabolites of the azo food dye tartrazine', Food and Chemical Toxicology, vol. 182, 114193. https://doi.org/10.1016/j.fct.2023.114193

TY - JOUR

T1 - Preparation, analysis and toxicity characterisation of the redox metabolites of the azo food dye tartrazine

AU - Pay, Ruth

AU - Sharrock, Abigail V.

AU - Elder, Riley

AU - Marie, Alaigne

AU - Bracegirdle, Joe

AU - Torres, Dan

AU - Malone, Niall

AU - Vorster, Jan

AU - Kelly, Libusha

AU - Ryan, Ali

AU - Josephy, P. David

AU - Allen-Vercoe, Emma

AU - Ackerley, David F.

AU - Keyzers, Robert A.

AU - Harvey, Joanne E.

N1 - Funding information: We are grateful to Te Apārangi Royal Society of New Zealand for a Catalyst Seeding Grant (20-VUW011-CSG), to the Wellington Medical Research Foundation for providing Research for Life Fellowship funding (Dr Abigail Sharrock), and to Victoria University of Wellington for PhD (Joe Bracegirdle) and summer (Ruth Pay) scholarships.

PY - 2023/12/1

Y1 - 2023/12/1

N2 - 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. Both 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.

AB - 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. Both 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.

KW - Azo dye

KW - Tartrazine

KW - FD&C yellow 5

KW - E102

KW - C.I. 19140

KW - Metabolite

KW - 4-Amino-3-carboxy-5-hydroxy-1-(4-sulfophenyl)pyrazole

KW - SCAP

KW - Gut microbiome

KW - Cell toxicity

U2 - 10.1016/j.fct.2023.114193

DO - 10.1016/j.fct.2023.114193

M3 - Article

SN - 0278-6915

VL - 182

JO - Food and Chemical Toxicology

JF - Food and Chemical Toxicology

M1 - 114193

ER -