476-39-1

Upstream product

• 76173-05-2 3,5,6,8-Tetraacetoxy-1-methyl-9,10-dioxo-7-((2S,3S,4R,5R,6R)-3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-2-yl)-9,10-dihydro-anthracene-2-carboxylic acid 
• 50-99-7 D-glucose 
• 137410-42-5 3,5,8-Trihydroxy-1-methyl-9,10-dioxo-7-((2S,3S,4R,5R,6R)-3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-2-yl)-9,10-dihydro-anthracene-2-carboxylic acid 

Downstream Products

• 954-07-4 1-methylanthraquinone 
• 84-65-1 9,10-phenanthrenequinone 

Relevant academic research and scientific papers

Production of Carminic Acid by Metabolically Engineered Escherichia coli

Carminic acid is an aromatic polyketide found in scale insects (i.e., Dactylopius coccus) and is a widely used natural red colorant. It has long been produced by the cumbersome farming of insects followed by multistep purification processes. Thus, there has been much interest in producing carminic acid by the fermentation of engineered bacteria. Here we report the complete biosynthesis of carminic acid from glucose in engineered Escherichia coli. We first optimized the type II polyketide synthase machinery from Photorhabdus luminescens, enabling a high-level production of flavokermesic acid upon coexpression of the cyclases ZhuI and ZhuJ from Streptomyces sp. R1128. To discover the enzymes responsible for the remaining two reactions (hydroxylation and C-glucosylation), biochemical reaction analyses were performed by testing enzyme candidates reported to perform similar reactions. The two identified enzymes, aklavinone 12-hydroxylase (DnrF) from Streptomyces peucetius and C-glucosyltransferase (GtCGT) from Gentiana triflora, could successfully perform hydroxylation and C-glucosylation of flavokermesic acid, respectively. Then, homology modeling and docking simulations were performed to enhance the activities of these two enzymes, leading to the generation of beneficial mutants with 2-5-fold enhanced conversion efficiencies. In addition, the GtCGT mutant was found to be a generally applicable C-glucosyltransferase in E. coli, as was showcased by the successful production of aloesin found in Aloe vera. Simple metabolic engineering followed by fed-batch fermentation resulted in 0.63 ± 0.02 mg/L of carminic acid production from glucose. The strategies described here will be useful for the design and construction of biosynthetic pathways involving unknown enzymes and consequently the production of diverse industrially important natural products.

Kinetic study of the equilibration between carminic acid and its two isomers isolated from cochineal dye

Carminic acid (CA) is a major component of cochineal dye used in food additives, cosmetics, and pharmaceuticals. CA and its isomers, 2-C-α-glucofuranoside and 2-C-β-glucofuranoside of kermesic acid (DCIV and DCVII, respectively), were isolated from cochineal dye and the equilibrium constants (K) between CA, DCIV and DCVII were investigated. DCIV was partially converted to CA and DCVII, and DCVII was converted to CA and DCIV, whereas CA was very stable and only very slightly converted to DCIV and DCVII. Most of the DCIV and DCVII was converted to CA under aqueous conditions. The kinetic rate constants (k) for the degradation of DCIV within the first day of incubation at 24°C was determined to be 0.901 d-1 and for the degradation of DCVII it was determined to be 1.102 d-1. The k value for the formation of CA from the remaining DCIV was calculated to be 0.146 d-1 and for the formation of CA from the produced DCVII it was found to be 0.148 d-1. The K values were calculated as 1.22×10-7, 2.61×10-3 and 2.36×10-3 mol/L for CA, DCIV and DCVII, respectively. These findings will be helpful for ensuring the safety and for aiding the quality assurance of cochineal dye products.

Synthesis of carminic acid, the colourant principle of cochineal

The first synthesis of carminic acid (7β-D-glucopyranosyl-3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-9,10- dihydroanthracene-2-carboxylic acid) is described. Selective C-glycosylation at the 7-position of ethyl and benzyl 3,5,8,9,10-pentamethoxy-1-methylanthracene-2-carboxylates with 2,3,4,6-tetra-O-benzyl-1-trifluoroacetyl-α-D-glucopyranose afforded intermediates which were oxidised to ethyl and benzyl 3,5,8-trimethoxy-1-methyl-9,10-dioxo-7-(2′,3′,4′,6′- tetra-O-benzyl-β-D-glucopyranosyl)-9,10-dihydroanthracene-2-carboxylate respectively. The benzyl compound was hydrogenolysed and the ethyl analogue hydrogenolysed and hydrolysed to give the same product, which was tetraacetylated and demethylated to afford 6-deoxycarminic acid tetraacetate, 3,5,8-trihydroxy-1-methyl-9,10-dioxo-7-(2′,3′,4′,6′- tetra-O-acetyl-β-D-glucopyranosyl)-9,10-dihydroanthracene-2-carboxylic acid. The pentamethoxy intermediates were obtained from 2-chloronaphthazarin by Diels-Alder addition to 3-alkoxycarbonyl-2,4-bis(trimethylsiloxy)penta-2,4-dienes to give alkyl 6-deoxykermesates. Methylation afforded the corresponding trimethyl ethers, which by reductive methylation gave the required pentamethoxy compounds. By known steps 6-deoxycarminic acid tetraacetate was converted into the 5,8,9,10-bisquinone, acetoxylation of which gave carminic acid octaacetate. Acidic hydrolysis afforded carminic acid.

The First Total Synthesis of Carminic Acid

The first synthesis of carminic acid (7β-D-glucopyranosyl-1-methyl-3,5,6,8-tetrahydroxy-9,10-anthraquinone-2-carboxylic acid), was accomplished by direct C-glucosylation of ethyl 3,5,8,9,10-pentamethoxy-1-methylanthracene-2-carboxylate, here synthesized, which affords ethyl 7-(2,3,4,6-tetra-O-benzyl-β-D-glucopyranosyl)-3,5,8,9,10-pentamethoxy-1-methylanthracene-2-carboxylate and carminic acid by regeneration of the masked functionalities.