Absorption, Distribution and Excretion
When color is given orally to rats, 3% is absorbed and excreted unchanged in urine and in bile: thus little is reduced in liver. ...After its iv injection in rats, 20-30% was excreted in bile.
... A trace to 1.5 percent of unchanged monomeric dyes was excreted in urine and bile during the first 24 hr after dosing. No unchanged dye was absorbed after administration of the polymeric derivatives. In animals dosed with sunset yellow and its polymer derivative, absorption of the azo-bound cleavage product 1-amino-2-naphthol-6-sulphonic acid was 8.5 and 6.9 percent, respectively, while absorption of the cleavage product sulphanilic acid was 37.4 and 0 percent, respectively. ...
In 5 animals dosed with 14C-sunset yellow (2.7 mg, 4.62 uCi) after 96 hours urinary excretion of radioactivity was 8.5 +/- 3.4% of the dose. The 24 hours urine collection from the sunset yellow rats contained 40% of the molar equivalents of sulfanilic acid. Intact dye in the 24 hours urine represented 1-2% of the dose. Peak fecal excretion occurred during the first 24 hours. The recovery of radioactivity was 94.5 +/- 5.7%. Total recovery of radioactivity was 103 +/- 3.3%.
Fourteen rats were dosed with sunset yellow within the range of 2-25 mg and within 72 hours excreted 0.3 and 1.5% of the administered dye in urine and bile respectively and 37% of the sulfanilic acid equivalents in the urine.

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Metabolism / Metabolites
When color is given orally to rats... unabsorbed was mainly reduced by intestinal bacteria and excreted as sulfanilic acid and 1-amino-2-hydroxy-6-naphthalenesulfonic acid in urine. ...n-Acetylsulfanilic acid as metabolite in rabbits after oral administration...
Sunset yellow FCF is easily reduced in vitro by bacteria present in intestine and cecum of rats. It binds with serum proteins.
The anaerobic reduction of 4... sulfonated azo dyes, amaranth, sunset yellow, new coccine and tartrazine, has been studied by incubating bacterial suspensions isolated from human feces and from the intestinal contents of rats with 50 um concentrations of the dyes in phosphate buffer pH 4 /with/ nitrogen as the gaseous phase. Human fecal flora from 5 male volunteers reduced the 4 dyes at mean rates of 38.4, 25.1, 18.2 and 6.5 nmol/mg/protein/hr, respectively. For each dye, there was little difference in the reduction rates effected by the bacterial suspensions from the different individuals in spite of considerable divergence in age, daily diets and living circumstances. ...The rates of amaranth and sunset yellow reduction by rat gut flora were 4-5 times higher than those by human fecal flora, but there was no significant difference between the two types of bacterial suspension in the reduction rates for new coccine and tartrazine. ...
When rabbits were fed 0.5 g/kg bw of the color, the following metabolites could be identified in 48 hours urine: sunset yellow (2%), sulfanilic acid (54%), p-acetamido benzene-sulfonic acid (23%), 1-amino-2-naphthol-6-sulfonic acid (55% in 24 hours). ... The metabolites in the urine were predominantly products resulting from the reductive fission of the azolinkage. The liver enzyme that reduces azolinkages plays little part in metabolism. Reduction of the color by the intestinal bacteria is therefore the most probable way to aromatic amines and aminosulfonic acids; these are then partly absorbed by the intestinal tract.
The sodium salt of 6-hydroxy-5-(phenylazo)-2-naphthalenesulfonic acid (SS-AN), which is a subsidiary color present in Food Yellow No. 5 [Sunset Yellow FCF, disodium salt of 6-hydroxy-5-(4-sulfophenylazo)-2-naphthalenesulfonic acid], was orally administered to Sprague-Dawley rats. Metabolite A, metabolite B, and unaltered SS-AN were detected as colored metabolites in the rat urine. Analysis of the chemical structures showed that metabolite A (major peak) was 6-hydroxy-5-(4-sulfooxyphenylazo)-2-naphthalenesulfonic acid, the sulfuric acid conjugate of SS-AN, and metabolite B (minor peak) was 6-hydroxy-5-(4-hydroxyphenylazo)-2-naphthalenesulfonic acid (SS-PAP), which is a derivative of metabolite A without the sulfuric acid. ...The orally administered SS-AN had been metabolized to the colorless metabolites (p-aminophenol 45.3%, o-aminophenol 9.4%, aniline 0.4%) in the 24-hr urine samples. Analysis of the colored metabolites... indicated the presence of metabolite A (0.29%), SS-PAP (0.01%), and SS-AN (0.02%) were detected in the 24-hr urine samples. Approximately 56% of SS-AN was excreted into the urine and the rest is probably excreted into feces.

Non-Human Toxicity Values
LD50 Mouse ip (Females) 4600 mg/kg bw
LD50 Mouse ip (Males) 5500 mg/kg bw
LD50 Rat ip 3800 mg/kg bw
LD50 Mice oral > 6000 mg/kg bw
For more Non-Human Toxicity Values (Complete) data for C.I. FOOD YELLOW 3 (8 total), please visit the HSDB record page.

[1]. Electro-Fenton oxidation of Sunset Yellow FCF azo-dye in aqueous solutions. Desalination, 2011, 274(1-3): 22-30.

[2]. Sunset yellow FCF, a permitted food dye, alters functional responses of splenocytes at non-cytotoxic dose. Toxicol Lett. 2013 Mar 13;217(3):197-204.

[3]. The modifying effect of selenium and vitamins A, C, and E on the genotoxicity induced by sunset yellow in male mice. Mutat Res. 2012 May 15;744(2):145-53.

Fd & c yellow no. 6 appears as orange-red crystals or a red powder. (NTP, 1992)
Sunset Yellow FCF is an organic molecular entity.

C16H10N2NA2O7S2

452.3693

451.972

2783-94-0

17730

Pink to red solid powder

390°C (dec.)

4.93

1

9

2

29

722

0

OIQPTROHQCGFEF-UHFFFAOYSA-L

InChI=1S/C16H12N2O7S2.2Na/c19-15-8-1-10-9-13(27(23,24)25)6-7-14(10)16(15)18-17-11-2-4-12(5-3-11)26(20,21)22;;/h1-9,19H,(H,20,21,22)(H,23,24,25);;/q;2*+1/p-2

disodium;6-hydroxy-5-[(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 (~221.06 mM)

Solubility in Formulation 1: 50 mg/mL (110.53 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.

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