Indigo carmine, or 5,5′-indigodisulfonic acid sodium salt, is an organic salt derived from indigo by aromatic sulfonation, which renders the compound soluble in water. Like indigo, it produces a blue color, and is used in food and other consumables, cosmetics, and as a medical contrast agent and staining agent; it also acts as a pH indicator. It is approved for human consumption in the United States and European Union.[3][4] It has the E number E132, and is named Blue No. 2 by the US Federal Food, Drug, and Cosmetic Act.
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| Names | |
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| Preferred IUPAC name
Disodium [2(2′)E]-3,3′-dioxo-1,1′,3,3′-tetrahydro[2,2′-biindolylidene]-5,5′-disulfonate | |
Other names
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.011.572 |
| E number | E132 (colours) |
| KEGG | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C16H8N2Na2O8S2 | |
| Molar mass | 466.36 g/mol |
| Appearance | purple solid |
| Melting point | >300 °C (572 °F) |
| 10 g/L (25 °C (77 °F)) | |
| Hazards | |
| GHS labelling: | |
 [1]
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| Warning | |
| H302[1] | |
| NFPA 704 (fire diamond) | |
| Pharmacology | |
| V04CH02 (WHO) | |
| Legal status | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Clinical data | |
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| Trade names | Bludigo |
| License data | |
| Identifiers | |
| E number | E132 (colours) |
| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.011.572 |
Uses
edit| Indigo Carmine (pH indicator) | ||
| below pH 11.4 | above pH 13.0 | |
| 11.4 | ⇌ | 13.0 |
Indigo carmine in a 0.2% aqueous solution is blue at pH 11.4 and yellow at 13.0. Indigo carmine is also a redox indicator, turning yellow upon reduction. Another use is as a dissolved ozone indicator[5] through the conversion to isatin-5-sulfonic acid.[5] This reaction has been shown not to be specific to ozone: it also detects superoxide, an important distinction in cell physiology.[6] It is also used as a dye in the manufacturing of capsules.
Medical uses
editIndigotindisulfonate sodium, sold under the brand name Bludigo, is used as a contrast agent during surgical procedures.[2] It is indicated for use in cystoscopy in adults following urological and gynecological procedures.[2][7] It was approved for medical use in the United States in July 2022.[specify][2][7]
In obstetric surgery, it may be used to detect amniotic fluid leaks. In urologic surgery, intravenous indigo carmine can be used to highlight portions of the urinary tract. The dye is filtered rapidly by the kidneys from the blood, and colors the urine blue. However, the dye can cause a potentially dangerous acute increase in blood pressure in some cases.[8]
Indigo carmine stain is not absorbed into cells, so it is applied to tissues to enhance the visibility of mucosa. This leads to its use for examination and diagnosis of benign and malignant lesions and growths on mucosal surfaces of the body.[9]
Food, pharmaceutical, cosmetic, and scientific uses
editIndigo carmine is one of the few blue food colorants. Others include the anthocyanidins and rare entites such as variagatic acid and popolohuanone.[10]
Safety and regulation
editThis article is missing information about legal status outside US/EU and most usages. (August 2024) |
Indigo carmin shows "genotoxicity, developmental toxicity or modifications of haematological parameters in chronic toxicity studies". Only at 17 mg/kg of body weight per day were effects on testes observed.[11]
References
edit- ^ a b "Indigo carmine". Sigma Aldrich. Retrieved 15 Feb 2022.
- ^ a b c d "Bludigo- indigotindisulfonate sodium injection". DailyMed. 7 November 2022. Retrieved 21 January 2023.
- ^ Summary of Color Additives for Use in United States in Foods, Drugs, Cosmetics, and Medical Devices, Food and Drug Administration
- ^ Current EU approved additives and their E Numbers, Food Standards Agency, 26 November 2010
- ^ a b Takeuchi K, Ibusuki T (March 1989). "Quantitative determination of aqueous-phase ozone by chemiluminescence using indigo-5,5'-disulfonate". Analytical Chemistry. 61 (6): 619–623. doi:10.1021/ac00181a025. PMID 2729594.
- ^ Kettle AJ, Clark BM, Winterbourn CC (April 2004). "Superoxide converts indigo carmine to isatin sulfonic acid: implications for the hypothesis that neutrophils produce ozone". The Journal of Biological Chemistry. 279 (18): 18521–18525. doi:10.1074/jbc.M400334200. PMID 14978029.
- ^ a b "NDA APPROVAL: Bludigo (indigotindisulfonate sodium) injection" (PDF). U.S. Food and Drug Administration.
This article incorporates text from this source, which is in the public domain.
- ^ Craik JD, Khan D, Afifi R (January–February 2009). "The Safety of Intravenous Indigo Carmine to Assess Ureteric Patency During Transvaginal Uterosacral Suspension of the Vaginal Vault". Journal of Pelvic Medicine & Surgery. 15 (1): 11–15. doi:10.1097/SPV.0b013e3181986ace.
- ^ Jang JY (November 2015). "The Past, Present, and Future of Image-Enhanced Endoscopy". Clinical Endoscopy. 48 (6): 466–475. doi:10.5946/ce.2015.48.6.466. PMC 4676674. PMID 26668791.
- ^ Newsome AG, Culver CA, van Breemen RB (July 2014). "Nature's palette: the search for natural blue colorants". Journal of Agricultural and Food Chemistry. 62 (28): 6498–6511. doi:10.1021/jf501419q. PMID 24930897.
- ^ Amchova P, Kotolova H, Ruda-Kucerova J (December 2015). "Health safety issues of synthetic food colorants". Regulatory Toxicology and Pharmacology. 73 (3): 914–922. doi:10.1016/j.yrtph.2015.09.026. PMID 26404013.