Indicaxanthin

Piattelli, M., Minale, L., and Prota, G., Isolation, structure and absolute configuration of indicaxanthin. Tetrahedron, 20, 2325, 1964. 

Wyler, H., Wilcox, M.E., and Dreiding, A.S., Umwandlung eines Betacyans in ein Betaxanthin, Synthese von Indicaxanthin aus Betanin, Helv. Chim. Acta, 48, 361, 1965. 

As for anthocyanins, betalains are found in vacuoles and cytosols of plant cells. From the various natural sources of betalains, beetroot (Beta vulgaris) and prickly pear cactus (Opuntia ficus indica) are the only edible sources of these compounds. In the food industry, betalains are less commonly used as natural colorants from plant sources than anthocyanins and carotenoids, probably related to their more restricted distribution in nature. To date, red beetroot is the only betalain source exploited for use as a natural food coloring agent. The major betalain in red beetroot is betanin (or betanidin 5-0-P-glucoside). Prickly pear fruits contain mainly (purple-red) betanin and (yellow-orange) indicaxanthin and the color of these fruits is directly related to the betanin-to-indicaxanthin ratio (99 to 1, 1 to 8, and 2 to 1, respectively in white, yellow, and red fruits)." ... 

After ingestion of cactus pear fruit pulp, both betanin and indicaxanthin were found in human plasma (with AUCo i2 h values of 0.46 and 29.2 lunol/hr/mL, respectively), partly associated with LDL, and in urine (3 and 76%, respectively, of the ingested compounds)," indicating that indicaxanthin was better absorbed than betanin. The bioavailability of indicaxanthin from prickly pear fruit pulp was 20 times that of betanin, suggesting differences in the fates of the two classes of betalains (betacyanin and betaxanthins) in the human body. In rats, betanin appeared to be... 

Butera, D. et al.. Antioxidant activities of Sicilian prickly pear (Opuntia ficus indica) fruit extracts and reducing properties of its betalains betanin and indicaxanthin, J. 

Proline, however, is the predominant amino acid and most interestingly, its betalamic acid adduct indicaxanthin is the major betalain pigment in cactus pear. Proline functions as an osmolyte, accumulating in water- and heat-stressed plant tissues, and in comparison to other amino acids, it exhibits an extraordinarily high solubility of 1623 mg/L water at 25°C. ... 

Allegra, M. et al.. Mechanism of interaction of betanin and indicaxanthin with human myeloperoxidase and hypochlorons acid, Biochem. Biophys. Res. Commun., 332, 837, 2005. 

As a rule, indicaxanthin and portulacaxanthin I exhibit the highest absorption maxima. The lowest are usually represented by amine addncts of betalamic acid such as miraxanthin The absolute values will also be affected by the... 

The chemical structures of betanin and indicaxanthin found in the prickly pear are depicted in Fig. 2.150. Pigments were extracted by homogenizing fresh fruit flesh with methanol (1 5, w/v). The suspension was fdtered and the liquid phase was applied for spectrophotometry and RP-HPLC. Liquid chromatographic separation was performed in an ODS column (250 X 4.6 mm i.d. particle size 5 pan) at ambient temperature. Gradient elution started with 1 per cent aqueous acetic acid and changed to 12 per cent solvent B in... 

Fig. 2.150. Chemical structures of betanin and indicaxanthin. Reprinted with permission from J. A. Femandez-Lopez et al. [324],...

Fig. 2.152. HPLC patterns of betalains from cactus pear studies. Peak 1 = indicaxanthin (fR = 16.8min) 2 = betanin (fR = 19.6min) 3 = isobetanin (fR = 22.8min). Reprinted with permission from J. A. Femandez-Lopez et al. [325],...

Betacyanins are red pigments and account for the red color of beets (Beta vulgaris). They are unique compounds to the Centrospermae. They have absorption spectra that resemble anthocyanins, but they contain nitrogen. An example is betanidin (1.66). Betacyanins are normally found as glycosides. Betaxanthins are chemically related to betacyanins, but they are not phenols. An example is indicaxanthin (1.67). These compounds are yellow pigments, and are also unique to the Centrospermae. 

I indicaxanthin indole-3-acetic acid iridoskyrim isochorismate isoflavone isoorientin 1.67 2.49 2.39 3.43 1.33 6.21... 

Impellizzeri, G. and Piattelli, M. (1972) Biosynthesis of indicaxanthin in Opuntiaficus-indica fruits. Phytochemistry, 11, 2499-502. 

Minale, L., Piattelli, M. and Nicolaus, R.A. (1965) Pigments of Centrospermae-IV. On the biogenesis of indicaxanthin and betanin in Opuntiaficus-indica Mill. Phytochemistry, 4, 593-7. 

The absolute configuration at C-15 was finally determined by peracid degradation of indicaxanthin (2), which had been previously correlated with betanidin (1)... 

A detailed NMR analysis revealed that indicaxanthin is present in CF3CO2H solution as a 65 35 mixture of its SE and 8Z stereoisomers (2a and 2b, respectively), which causes a partial doubling of the NMR signals (32). In CF3CO2D an exchange of the protons at positions 8 and 14 takes place in accord with theoretical considerations and observations on related 1,7-diazaheptamethinium systems. 

Indicaxanthin can be prepared from betanin (5) by amino acid exchange with L-proline in aqueous ammonia (72). The product obtained by this method is partially epimerized at C-11, in contrast to betanidin which is not affected under these conditions (29). Unlike betanidin and isobetanidin, the two epimers of indicaxanthin have not yet been separated by chromatographic or electrophoretic methods. 

The betalamic acid derivatives obtained by total synthesis have been used for the preparation of natural and unnatural betalains following the procedures developed for amino acid exchange described earlier (Scheme 4). Reaction of the 9 1 ElZ mixture of semicarbazone 66 with the p-toluenesulfonate salt of (S)-cyclodopa methyl ester in dilute methanolic HCl afforded betanidin trimethyl ester (9), which was hydrolyzed with aqueous HCl to yield a 4 6 mixture of betanidin and isobetanidin 91). In the case of L-proline, the reaction had to be carried out in dilute aqueous ammonia because of the sensitivity of the resulting indicaxanthin (2) toward acids. Most likely, an inseparable mixture of 2 and its C-13 epimer T was obtained under these conditions. 

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