Carotenal, /3-apo

PApo-8 -carotenal. The specifications of this colorant. (38) were discussed earlier. P-Apo-8 -carotenal has provitamin activity with 1 g of the colorant equal to 1,200,000 lU of vitamin A. Like all crystalline carotenoids, it slowly decomposes ia air through oxidatioa of its coajugated double boads and thus must be stored ia sealed coataiaers uader an atmosphere of iaert gas, preferably under refrigeration. Also like other carotenoids P-apo-8 -carotenal readily isomerizes to a mixture of its cis and trans stereoisomers when its solutions are heated to about 60°C or exposed to ultraviolet... 

P-Apo-8 -carotenal is sold as a dry powder, as 1—1.5% vegetable oil solutions, as 20% suspensions ia vegetable oil, as 2—4% solutioas ia a mixture of moaoglycerides and DL-a-tocopherol, and as 10% dry beadlets. The vegetable-oil suspensions are purpHsh black fluids at room temperatures that set to... 

Unknown until 1950 when E. Haxo isolated it from an edible mushroom Cantharellus cinnabarinus canthaxanthin has since been identified in sea trout, algae, daphnia, salmon, brine shrimp, and several species of flamingo. Crystalline canthaxanthin is prepared synthetically from acetone or P-ionone using procedures similar to those used for -carotene and P-apo-8 -carotenal (55). 

Canthaxanthin crystallines from various solvents as brownish violet, shiny leaves that melt with decomposition at 210°C. As is the case with carotenoids in general, the crystals are sensitive to light and oxygen and, when heated in solution or exposed to ultraviolet light or iodine, form a mixture of cis and trans stereoisomers. Consequentiy, crystalline canthaxanthin should be stored under inert gas at low temperatures. Unlike the carotenoid colorants P-carotene and P-apo-8 -carotenal, canthaxanthin has no vitamin A activity. It is chemically stable at pH 2—8 (the range normally encountered in foods) and unaffected by heat in systems with a minimal oxygen content. 

The solubility of canthaxanthin in most solvents is low compared with P-carotene and P-apo-8 -carotenal. Oil solutions of canthaxanthin are red at all concentrations. Aqueous dispersions are orange or red depending on the type of emulsion prepared. 

O. Isler, R. Ruegg, and P. Schudel, Chimia 15, 208—226 (1961). Includes a discussion of P-carotene, P-apo-8 -carotenal, and canthaxanthin from the standpokit of preparation, toxicity, analysis, and appHcation. 

Although the carotenoids can be obtained from natural sources, it is far more economical to manufacture them for commercial use (130). Three have been manufactured for many years -carotene [7235-40-7] (42), canthaxanthin [514-78-3] (43), and P-apo-8 -carotenal [1107-26-2] (44) (131). Their stmctures are shown ia Figure 1. 

Fig. 1. Carotenoid pigments -carotene (42), P-apo-8 -carotenal (44), and canthaxanthin (43) = structure (42) with ketone groups at the 4 and 4 positions.

Carotenoids are also present in animal products such as eggs, lobsters, greyflsh, and various types of hsh. In higher plants, they occur in photosynthetic tissues and choloroplasts where their color is masked by that of the more predominant green chlorophyll. The best known are P-carotene and lycopene but others are also used as food colorants a-carotene, y-carotene, bixin, norbixin, capsanthin, lycopene, and P-apo-8 -carotenal, the ethyl ester of P-apo-8-carotenic acid. These are Upid-soluble compounds, but the chemical industry manufactures water-dispersible preparations by formulating coUoid suspensions by emulsifying the carotenoids or by dispersing them in appropriate colloids. ... 

Carotenoid oxidation products are also supposed to have detrimental effects in vivo. As mentioned earlier, they are suspected to be involved in the adverse effects of high doses of 3-carotene supplementation in smokers and asbestos workers (CARET and ATBC studies) and in smoke-exposed ferrets. The mechanisms potentially involved have been investigated in vitro. P-Apo-8 -carotenal, an eccennic cleavage oxidation product of P-carotene, was shown to be a strong inducer of CYPlAl in rats, whereas P-carotene was not active. Cytochrome P450 (CYP 450) enzymes thus induced could enhance the activation of carcinogens and the destruction of retinoic acid. ... 

Mordi, R.C. et al.. Oxidative degradation of beta-carotene and P-apo-8-carotenal,... 

Gradelet, S. et al., Beta-apo-8-carotenal, but not beta-carotene, is a strong inducer of liver cytochromes P4501A1 and 1A2 in rat, Xenobiotica, 26, 909, 1996. 

Step. In fact, citranaxanthin and reticulaxanthin, reported as natural carotenoids from citrus, are aldol condensation products formed from P-apo-8-carotenal and P-citraurin, respectively." In such samples, the extraction can be performed with MeOH and EtOAc. 

For HPLC, it is necessary to establish the relationship between the detector signal, of which the most used is peak area, and the concentrations of the pigments. Calibration curves for external quantification should be constructed for each carotenoid. Internal calibration is also used for quantification of carotenoids, using as internal standards all-trfln5 -p-apo-8-carotenal, ° Sudan 1, and decapreno-P-carotene. ... 

Stewart, L, and Wheaton, T.A., Conversion of 3-citraurin to reticulaxanthin and 3-apo-8 -carotenal to citranaxanthin during isolation of carotenoids from citrus. Phytochemistry, 12, 2947, 1973. 

The product distribution resulting from P-carotene oxidization by 02 was studied by Stratton et al. (1993) using reverse-phase HPLC, UV-vis spectrophotometry, and mass spectrometry. The oxidation products were identified as [3-ionone, P-apo-14 -carotenal, (i-apo-IO -carotenal, P-apo-8 -carotenal, and P-carotene-5,8-endoperoxide. The formation of 5,8-endoperoxide derivative by a [4+2] Diels-Alder addition mechanism was also reported in the 02-mediated oxidation of P-carotene in reverse micelles (Montenegro et al. 2002), P-ionone (Borsarelli et al. 2007), and of the A1E retinoid derivative (Jockusch et al. 2004). 

Mordi, RC, Walton, JC, Burton, GW, Hughes, L, Ingold, KU, Lindsay, DA, and Moffatt, DJ, 1993. Oxidative degradation of beta-carotene and beta-apo-8 -carotenal. Tetrahedron 49, 911-928. 

P-apo-8 -carotenal, 24 560-561 P-aroylacrylic acids, 15 486 P-brasses, effect of alloying on mechanical properties, 7 677... 

E 160f Ethyl ester of beta-apo-8 -carotenic acid (C30) 40825... 

Beta-apo-8-carotenal Not to exceed 15 mg/lb of solid or semisolid food or 15 mg/pint of liquid food El 60a 0-5... 

Fig. 2.15. Chromatographic profile of a tomato juice extract at a column temperature of 7°C. Peak identification 4 =/0-apo-8 -carotenal 9 = (E)-/0-carotene 11 = 13(Z)-/0-carotene 10 = 9(Z)-/0-carotene 7 = lycopene 7a = 9(Z)-lycopene 7b = 15(Z)-lycopene. Reprinted with permission from V. Bohm [39],...

Fig. 2.16. HPLC profile of carotenoids in an extract of vegetable soup. An expansion of the profile from 30 to 39 is shown in the inset (A). Monitored wavelengths were 436, 440, 464, and 409 nm for peaks 9,10,11,12, and 14, respectively, in the inset (A). Peak identification 1 + 1" = all-trans-lutein and cw-lutein 2 = 5,6-dihydroxy-5,6-dihydrolycopene (lycopene-5,6-diol) 3 = j3-apo-8 -carotenal (internal standard) 4 = lycopene 1,2-epoxide 5 = lycopene 5,6-epoxide 6 = 1,2-dimethoxyproly-copene (tentative identification) 7 = 5,6-dimethoxy-5,6-dihydrolycopene 8 = lycopene 9 = pheo-phytin b 10 = neurosporene 11 = (-carotene 12 = pheophytin a 13 = (-carotene 14 = pheophytin a isomer and (-carotene 15 = a-carotene 16 and 16" = all-trans-/fcarotene, cis-/J-carotene 17 and 17" = all-trans- or cA-phytofluene 18 and 18" = all-trans- or cw-phytoene. Reprinted with permisson from L. H. Tonucci et al. [40].

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