Carminic acid
Carminic acid is a red glucosidal hydroxyanthrapurin with the chemical formula \(C_{22}H_{20}O_{13}\), naturally occurring in some scale insects, notably the cochineal, Armenian cochineal, and Polish cochineal. These insects produce carminic acid as a deterrent against predation. The compound is notable for its use as the coloring agent in carmine, a pigment derived from the aluminum salt of carminic acid. This natural dye has been utilized since at least 700 CE, with evidence of its use by natives of Peru for textile dyeing. Carminic acid's structure features a core anthraquinone linked to a glucose sugar unit, and it was first synthesized in a laboratory in 1991. In 2018, the microbe Aspergillus nidulans was genetically engineered to produce carminic acid, marking a significant advancement in its production methods[1].
Carminic acid is primarily harvested from Dactylopius coccus, a species of scale insect native to Mexico and South America. These insects are cultivated or collected from wild populations for their carminic acid content, which is extracted by soaking the dried insects in water. The acid serves as a potent feeding deterrent against ants and possibly acts as a visual aposematic signal, although its effectiveness against vertebrates has not been thoroughly tested. Some predators, like the pyralid moth Laetilia coccidivora, can sequester carminic acid from cochineals for their own defense[1].
The biosynthesis of carminic acid in the cochineal insect involves a polyketide secondary metabolite pathway. Initially, it was unclear whether the structure of carminic acid originated from the type II polyketide or shikimate pathways. However, the isolation of a key intermediate exclusive to the polyketide pathway clarified its biosynthetic origin. The biosynthesis process can be divided into three stages: initiation, elongation, and cyclization, involving various enzymes such as transferases, ketoacyl synthase, and cyclase domains[1].
Carminic acid finds extensive use in foods, pharmaceuticals, toiletries, and other products as a dye. It is also employed as a microscopic stain and biological marker. Its safety and efficacy as a natural-based food colorant have been the subject of comprehensive reviews, highlighting its significance in the food industry[1][5][7][8]. Additionally, carminic acid's role as a feed additive for pets has been evaluated, confirming its safety and efficacy under certain conditions[12][16].
In recent years, the demand for carminic acid has increased, prompting research into more sustainable and efficient production methods. Metabolic engineering and the development of heterologous production systems in microbes such as A. nidulans and E. coli represent promising approaches to meet this demand. These advancements could potentially alleviate the environmental and economic pressures associated with traditional cochineal farming, while also addressing consumer concerns about animal-derived products and genetically modified organisms[10][15].
Citations:
[1] https://en.wikipedia.org/wiki/Carminic_acid
[2] https://www.sciencedirect.com/science/article/pii/S0001868623002191
[3] https://www.fishersci.com/store/msds?countryCode=US&language=en&partNumber=AC346630050&productDescription=CARMINIC+ACID%2C+70-90%25+5GR&vendorId=VN00032119
[4] https://pubchem.ncbi.nlm.nih.gov/compound/Carminic-acid
[5] https://pubs.acs.org/doi/10.1021/jacs.0c12406
[6] https://www.extrasynthese.com/MSDS/GBR/0470.pdf
[7] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/carminic-acid
[8] https://pubmed.ncbi.nlm.nih.gov/38086153/
[9] https://datasheets.scbt.com/sc-214669.pdf
[10] https://www.smithsonianmag.com/innovation/scientists-are-making-cochineal-a-red-dye-from-bugs-in-the-lab-180979828/
[11] https://inchem.org/documents/jecfa/jecmono/v46je03.htm
[12] https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2022.7609
[13] https://www.chm.bris.ac.uk/motm/carminic-acid/carminic-acidh.htm
[14] https://www.efsa.europa.eu/en/efsajournal/pub/4288
[15] https://www.nature.com/articles/s41598-018-30816-9
[16] https://pubmed.ncbi.nlm.nih.gov/36312449/
[17] https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/carminic-acid
[18] https://drugs.ncats.io/substance/CID8Z8N95N