Crocetin

The coloring principles of saffron are crocin [42553-65-1] and crocetin [27876-94-4J. Crocin is the gentiobiose diester of crocetin (44)... 

Crocetin is a dicarboxyUc acid that forms brick red rhombs from acetic anhydride that melt with decomposition at about 285°C. It is very sparingly soluble in water and most organic solvents but soluble in pyridine and similar organic bases as well as in dilute sodium hydroxide. 

Crocetin [27876-94-4] Cl Natural Yellow 6 Cl 75100) occurs in saffron as crocin [42553-65-1] (46), the digentiobiose ester of crocetin (47). 

The dye molecule in saffron is the carotenoid beta-gentiobiose crocetin. It is related to beta-carotene, and you can see the relationship in the center of the molecule. That center portion is the carotenoid pigment crocetin ... 

On either side of the crocetin molecule is a disaccharide molecule called beta-gentiobiose, and the result is the molecule that gives saffron its yellow color. 

Crocus sativus petals Crocin, crocetin (saffron) Food colouring... 

FIGURE 4.2.2 Structures of carotenoids found in paprika (capsanthin and capsombin), saffron and gardenia (crocetin derivatives), and annatto (bixin and norbixin). 

Carmona, M. et al., Crocetin esters, picrocrocin and its related compounds present in Crocus sativus stigmas and Gardenia jasminoides fruits. Tentative identification of seven new compounds by LC-ESl-MS, J. Agric. Food Chem., 54, 973, 2006. 

The aroma and red color of the spice saffron are partly due to the style-specific accumulation of carotenoid cleavage products produced by both enzymatic and thermal degradation. M. Giaccio reviewed the renewed interest in saffron as a colorant, spice, and nutraceutical. " Crocetin is a C20 apocarotenoid derived from zeaxanthin (Figure 5.3.4B). ... 

FIGURE 5.3.4B Proposed biosynthetic pathway to crocetin and safranal. Enzyme abbreviations and enzyme activities are defined in Table 5.3.1. 

Giaccio, M., Crocetin from saffron an active component of an ancient spice, Crit. Rev. Food Sci. Nutr. 44, 155, 2004. 

Moraga, A.R. et al., Glucosylation of the saffron apocarotenoid crocetin by a gluco-syltransferase isolated from Crocus sativus stigmas, Planta 219, 955, 2004. 

There have been many applications of the Wittig reaction in multistep syntheses. The reaction can be used to prepare extended conjugated systems, such as crocetin dimethyl ester, which has seven conjugated double bonds. In this case, two cycles of Wittig reactions using stabilized ylides provided the seven double bonds. Note the use of a conjugated stabilized ylide in the second step.250... 

The reaction of crocetin bisazolide has also been achieved with unprotected ( ) / -D-glucose in excellent yields (67% from the imidazolide 70% from the 1,2,4-triazolide). Esterification takes place exclusively at the anomeric C-atom, and produces only the f -anomer. The higher acidity of the anomeric hydroxyl group compared with the other... 

The esterification can also be carried out as a one-pot reaction without isolation of the azolide for example, an 80% yield of crocetin bis(/ -D-glucosyl ester) was obtained via the triazolide. 1953 Reactions of 8 -apo-/ -carotene-8 -oic acid with D-galactose or lactose were claimed to proceed also with a high degree of regioselectivity.11963... 

The ratio of the a- to the j -anomeric D-glucosyl ester can be influenced by changing the reaction conditions. In DMF the a-anomer of the crocetin bis(D-glucosyl ester) was formed in about 70% yield.[196] Esterification of D-glucose with the imidazolides of benzoic acid or stearic acid in pyridine furnished a mixture of the a- and j -anomers of the C(l) glucosyl ester.[196]... 

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