Kermesic acid

A similar effect can be observed in anthaquinones, mainly for the presence of an hydroxyl group. The ionization of hydroxyl groups under basic conditions also undergoes a bathochromic shift. Alizarin has two absorption bands in the vis region, simated at 567 and 609 nm carminic acid has a visible absorption maximum at around 500 nm and kermesic acid at 498 mn. 

Madder, Armenian cochineal, lac dye historical samples pigment and wall painting Alizarin, munjistin, purpurin, xanthopurpurin, rubiadin, laccaic acid A, laccaic acid B, carminic acid, kermesic acid, flavokermesic acid HCI/MeOH/ h2o A H20 B ACN with TFA 275 nm/ESI ( ) HPLC optimization... 

Fig. 2.32. Chromatograms obtained at 420 and 500 nm for pure cochineal (a) and for cochineal adulterated by erythrosin (b), at a concentration of 0.35 X10-3 kg per kg cochineal, and by trans-fi-carotene (c) at a concentration of 6X10-3 kg per kg cochineal. Cochineal pigments dcH, dcIH, dcIV and dcVII, unknown pigments of D. coccus Costa ca, carminic acid fl, flavokermesic acid and ka, kermesic acid. marks the peak of the added colourant. Reprinted with permission from M. Gonzalez et al. [72].

Porphyrophora polonica L. (Polish cochineal) contains small amounts of the kermes dyes kermesic acid and flavokerme-sic acid besides the cochineal dye carminic acid. These secondary components cannot be identified unless they have previously been concentrated. 

Porphyrophora hameli BRANDT (Armenian cochineal) contains nearly exclusively carminic acid. It has been reported that high-performance liquid chromatography (HPLC) has also identified a trace of kermesic acid, but TLC has not provided any clear proof of the presence of this secondary component in Armenian cochineal, even after previous concentration. 

Indigenous in the Mediterranean area and in Asia Minor. Constituents (See also table V) Kermes contains kermesic acid (XXVI) and a small amount of flavokermesic acid (61) whose constitution has not yet been determined. 

Constituents (See also table V) Polish cochineal contains car-minic acid (XXVII) and kermesic acid (XXVI), whose quantitative ratio has been determined by HPLC and is reported by Whiting to be 5 1 to 10 1 and by Wouters 15 1 (10). 

Constituents (See also table V) Armenian cochineal contains Carminic acid (XXVII), as reported by Kurdian (73) in 1941 without any indication of the identification method used. It could also contain a very small amount of kermesic acid (XXVI), as Wouters found by investigations with HPLC (74). 

Armenian cochineal may have been an important article of commerce in earlier times (10). Masschelein-Kleiner and Maes (75) identified carminic acid on ten samples of Egyptian textiles from the 5th to the 7th century A.D., but not kermesic acid. This result applies only to Armenian cochineal and not to any other of the dyes known in antiquity. The authors also found Armenian cochineal on various Nubian and Hebrew textiles. 

When the improved method of extraction is used for stripping madder dyes with 10% sulfuric acid and ethyl acetate (see page 202), and the ethyl acetate layer is not stained yellow, but orange, this could indicate the presence of insect dyes containing kermesic acid (XXVI). 

For the separation of the kermes dyes kermesic acid and flavo-kermesic acid the following solvents are suitable according to my own experience ... 

The thin-layer chromatogram shows at first sight that the red samples of the coronation robe and of the Tunicella have been dyed with kermes (Kermococcus vermilio PLANCHON). As the comparison shows, not only the green spot of kermesic acid, but also the red spot of flavokermesic acid is clearly visible. 

In the case of lac dye, clearly the separation of the laccaic acids A, B, C, D, and E (39-42) can be seen, and in the case of kermes, the separation into kermesic acid (green spot) and flavokermesic acid (red spot) can be seen. References 39-42 describe the determination of the constitutions of the laccaic acids A-E and indicate their constitutions. 

Due to the spiraling price of cochineal in the mid eighties, synthesis of carminic acid appeared to be a viable commercial proposition. This seemed at first to be readily soluble simply by the glucosylation of kermesic acid, a process conceived to be the probable biosynthetic pathway. However, numerous studies of this potential route had no useful outcome (ref. 85). Nevertheless in view of the failure of several routes from different retrosynthetic... 

Both carminic aid and kermesic acid are members of the polyhydroxyquinone series which are mostly based on 1-methyl-3,6,8-trihydroxyantraquinone (deoxyerythrolaccin) (ref. 192) and have been termed the lac pigments. The natural occurrence of these compounds was considered to be only in coccid insects until they were isolated later from higher plants such as Aloe saponaria Haw (ref. 193). 

From classical degradative work on both carminic and kermesic acids (ref. 199, 200) the former was recognized as an anthraqinone resembling the latter and it was formulated (ref.201) as structure (A). This early work led to the surmise... 

In a different approach it was found that (E) and (Z) 3-alkoxy-2,4-bis(trimethylsiloxy)penta-1,3-dienes (the methyl, ethyl and benzyl esters were used) were more easily prepared dienes than monotrimethylsilyl enolic methyl ethers such as compound A used in the first synthesis of kermesic acid due to the unwanted occurrence of C- as well as O-methylation in the methylation of methyl diacetylacetate. 

---