Absorption, Distribution and Excretion
Rats were fed a diet containing 5.19% Allura Red. Observations showed that 0.1% and 29% of the intact dye were excreted in urine and feces, respectively. In a subsequent study, rats and dogs were pretreated daily with non-radioactive Allura Red. The animals were then injected with a 35S-labeled compound, and excretion and distribution patterns were observed for up to 72 hours. Absorption of the compound was limited in both animals, with feces being the primary route of excretion. In dogs, 92–95% of the recovered radioactive material appeared in feces within 72 hours; in rats, 76–92% of the recovered radioactive material appeared in feces within the same timeframe. The recovery rates of the dye in rat and dog urine were 5.7%–19.8% and 2.7%–3.6%, respectively. Significant radioactive residues were detected in the intestinal contents of both animals and in the cleansed intestines of rats after sacrifice. This is believed to be due to the compound adhering to the intestinal wall, as the radioactive residue in the entire carcass and viscera of these animals was less than 0.4% of the administered dose. Several metabolites were also found in feces and urine, possibly products of azo reduction in the gastrointestinal tract (two of which were identified as aromatic amines, with p-cresolsulfonic acid as the major metabolite). Furthermore, significant residues were observed in the cleansed intestines of rats, likely due to the compound adhering to the intestinal wall. In the urine of both animals, cresolsulfonic acid was the major metabolite of Allura Red, while the parent compound was undetectable. In addition, two other unidentified metabolites were found in rat urine. In rat fecal extracts, kressidin sulfonic acid was a major metabolite, along with two unknown metabolites and the parent compound. Canine fecal samples showed the same metabolite pattern as rats, with one additional unknown metabolite found. The Rf value of an unknown metabolite in urine was the same as that in feces, indicating that they are the same metabolite. The varying Rf values of other unknown metabolites suggest that these metabolites are distinct. It is speculated that the gut microbiota performs an azo reduction reaction on the dye, producing two components of the parent compound: 2-methoxy-5-methylaniline-4-sulfonic acid (krexidine-4-sulfonic acid) and 1-amino-2-naphthol-6-sulfonic acid. It appears that only a very small amount of the intact red dye is absorbed and excreted in the urine, while the majority is excreted as metabolites in the feces.

Interactions
In this study, the dye and its alumina lake were applied in aqueous solution to the palmar forearms of 200 subjects for 10 days, every other day for 24 hours each time, followed by a 14-day rest period. Subsequently, a challenge test sample was applied to fresh skin on the back of the scapula and treated with a 24-hour occlusion therapy. During the induction period, the dye did not cause irritation or allergic reactions; during the challenge test, it did not cause contact dermatitis. …Allura Red and its lake were evaluated under occlusion conditions for 5 cycles (48 hours, applied every other day). These sites had previously been irradiated with a xenon lamp for 5 minutes, the light from which was filtered through a filter equivalent to window glass to limit subjects' exposure to long-wave radiation that would not cause erythema. After the induction exposure, subjects had a 10-day rest period, and then the pigment was applied to fresh skin sites, irradiated with a xenon lamp for 5 minutes, followed by removal of the pigment and evaluation of the irradiated sites. The results showed that Allura Red did not cause photosensitivity in 25 subjects. In 2006, the Korean Food and Drug Administration reported that combinations of food colorings such as Allura Red AC, Tartrazine, Sunset Yellow FCF, Amaranth, and Brilliant Blue FCF were widely used in food production. Although the intake of each food coloring is controlled according to the Acceptable Daily Intake (ADI), there is currently no clear information on how these additive combinations affect food safety. This study investigated the effects of using these colorings alone and in combination on neural progenitor cells (NPCs, a biomarker of developmental stage) and neurogenesis (reflecting the function of the adult central nervous system (CNS)). In a developing CNS model, Allura Red AC and Amaranth reduced the proliferation and survival of mouse pluripotent neural progenitor cells (NPCs). Among several combinations tested in mouse models, the combination of Tartrazine and Brilliant Blue FCF (at a dose 1000 times higher than the Korean average daily intake) significantly reduced the number of newly generated cells in the hippocampus of adult mice, indicating a strong adverse effect on hippocampal neurogenesis. However, other combinations, including Allura Red AC and Amaranth Red, did not affect neurogenesis in the dentate gyrus of adult mice. Evidence suggests that most tar-based food colorings, used alone and in combination, are likely safe for neurogenesis in developing NPCs and adult mouse hippocampuses…

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Non-human toxicity values
LD50 Dog oral (male) > 5,000 mg/kg body weight [EPA/Office of Pollution Prevention and Toxic Substances; High-yield Challenge Program (HPV) comprehensive summary and testing program for the following substances: 2-naphthalenesulfonic acid, 6-hydroxy-5-
Rat oral LD50 > 10,000 mg/kg body weight [EPA/Office of Pollution Prevention and Toxic Substances; High-yield Challenge Program (HPV) comprehensive summary and testing program for the following substances: 2-naphthalenesulfonic acid, 6-hydroxy-5-
Rabbit skin LD50 10,000 mg/kg body weight

[1]. Characterisation of Interaction Between Food Colourant Allura Red AC and Human Serum Albumin: Multispectroscopic Analyses and Docking Simulations. Food Chem. 2015 Mar 1;170:423-9.

Allure Red AC is a naphthalenesulfonic acid.

C18H14N2NA2O8S2

496.4219

495.998

25956-17-6

33258

Brown to reddish brown solid powder

300ºC

5.247

1

10

3

32

809

0

CEZCCHQBSQPRMU-UHFFFAOYSA-L

InChI=1S/C18H16N2O8S2.2Na/c1-10-7-14(16(28-2)9-17(10)30(25,26)27)19-20-18-13-5-4-12(29(22,23)24)8-11(13)3-6-15(18)21;;/h3-9,21H,1-2H3,(H,22,23,24)(H,25,26,27);;/q;2*+1/p-2

disodium;6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~100 mg/mL (~201.44 mM)
DMSO : ~62.5 mg/mL (~125.90 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)