Opuntia ficus-indica Indicaxanthin

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)." ... 

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. 

Impellizzeri, G., and M. Piattelli Biosynthesis of Indicaxanthin in Opuntia ficus-indica Fruits. Phytochem. 11, 2499 (1972). 

Minale, L., M. Piattelli, and R.A. Nicolaus Pigments of Centrospermae IV. On the Biogenesis of Indicaxanthin and Betanin in Opuntia ficus-indica Mill. Phyto-chem. 4, 593 (1965). 

Betalains are red (betacyanins) or yellow pigments (betaxanthins) of Centrospermae and the pilei of some mushrooms (Fig. 292). Examples are betanin (betanidin-5-glucoside), the pigment of red beets, and indicaxanthin a pigment of Opuntia ficus-indica flowers and of the fly agaric (Amanita muscaria). Betalains are derivatives of (S)-betalamic acid. In the formation of betacyanins (S)-betala-mic acid condenses with L-cyclodopa (D 22.1.3), in case of betaxanthins with some other amines or amino acids, e.g., L-proline (D 17). Betacyanins and betaxanthins attract pollinators if present in plant flowers (E 5.5.1) and animals... 

Betaxanthins are yellow pigments (xanthos = yellow). An example is indicaxanthin from the Indian fig Opuntia ficus-indica. It consists of a pyridine derivative to which a proline ring is attached (Fig. 128). Bio-synthetically, the pyridine ring is furnished by dihydroxyphenylalanine (DOPA) after certain modifications and the proline ring by the amino acid... 

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