Betanidin Betanin

The study of these fragments, coupled with the results of additional research (139), estabUshed the stmcture of betanin [7659-95-2] (50). Betanidin [37279-84-8] was synthesized in 1975 (140). A small amount of two yellow pigments is present also in beets (51). These have no value as food dyes. 

Wyler, H., Mabry, T.J., and Dreiding, A.S., Zur Struktur des Betanidins tJber die Konstitution des Randenfarbstoffes Betanin, Helv. Chim. Acta, 46, 1745, 1963. 

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)." ... 

Portulaca grandiflora Hooker Song Ye Mo (Purslane) (whole plant) Portulal, betacyanin, betanin, betanidin.55 Treat throat swelling and pain, externally for bums, wounds and infections. 

Figure F3.1.1 Isocratic gradient LC chromatogram of betacyanin pigments. Peak A betanin peak B isobetanin peak C betanidin, and peak D isobetanidin. Adopted from Schwartz and von Elbe (1980).

The high-performance liquid chromatography method (see Basic Protocol 2) allows for the separation of individual betanin and its aglycon betanidin and their isomers. The agly-con is naturally occurring in beet tissue, but in relatively small amounts. The isomers, isobe-tanidin and isobetanin, are easily formed when solutions of beet extract are subjected to either heat or acid (Schwartz and von Elbe, 1983). The... 

Fig. 19 Formula of betacyanins R, R = OH (betanidin, isobetanidin) R, R = O-glucose (betanin, iso-betanin) R, R = 2 -glucuronic acid-glucose (amaranthin, isoamaranthin) R, R = O-glucose-6-sulfate (prebetanin, isoprebetanin). (From Ref. 215.)...

Fig. 22 HPLC separation of betalains in fermented red beet root extract, (a) Detection of betacyanins at 538 nm. Peaks 1 = betanin, 2 = isobetanin, 3 = betanidin, 4 = isobetanidin, 5 = prebetanin. (b) Detection of betaxanthins at 477 nm. Peaks 1 = vulgaxanthin I, 2 = vulgaxanthin II, 3 = betanin, 4 = isobetanin, 5 = betanidin, 6 = isobetanidin, 7 = prebetanin. (From Ref. 239.)...

Fig. 23 HPLC separation of betacyanin pigments on a /xBondapak Cls column. Peaks A = betanin, B = isobetanin, C = betanidin. D = isobetanidin. (From Ref. 249.)...

Betanidin has three carboxyl groups (pka = 3.4), two phenol groups (pHa = 8.5), and asymmetric carbons at positions 2 and 15. The 15-position is easily isomerized under acid or basic conditions in the absence of oxygen to yield isobetanidin. Under alkaline conditions and in the presence of glutamine or glutamic acid, betanin can be converted to vulgaxanthin (Mabry 1970). 

It has only recently been discovered that acylated betacyanins exhibit intramolecular co-pigmentation that may also lead to stabilization of the chromophor, betanidin (Schliemann and Strack, 1998), a phenomenon which is well-known for anthocyanins (Brouillard and Dangles, 1993). Esterification of the sugar moieties of betanin (betanidin 5-0-glucoside), gomphrenin I and bougainvillein-v with hydroxycinnamates leads to bathochromic shifts... 

Heuer, S. and Strack, D. (1992) Synthesis of betanin from betanidin and UDP-glucose by a protein preparation from cell suspension cultures of Dorotheanthus bellidiformis (Burin, f.) N.E.Br. Planta, 186, 626-8. 

Betanidin (1) constitutes the basic structural unit of all betacyanin pigments. The compound occurs as its glucoside betanin (5) in red beets and is therefore easily accessible. The chemistry of 1 has been intensively studied by Dreiding s... 

The (25) configuration of betanidin has been determined by the identification of degradation product 7 as (5)-cyclodopa (5). For the determination of the absolute configuration at C-15, studies on the stereochemical relationship of betanidin (1) and isobetanidin (6) were of importance. It was found that on hydrolysis of betanin (5) under drastic conditions (18% HCl, 87°C) the ratio of 6 to 1 formed increased with the reaction time, whereas with concentrated HCl at room temperature the aglycone contained only 5% of 6 (29). On treatment of either pure 1 or 6 with 0.4 N KOH at 25°C with exclusion of oxygen, a 1 2 equilibrium mixture of the two isomers was formed. That the epimerization takes place at C-15 is indicated by the fact that both isomers gave the same optically... 

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. 

Betalains occur in centrospermae, mainly in red beets, but also in some cactus fruits and mushrooms. They consist of red-violet betacyanins 540 nm) and yellow betaxanthins (Alliax 480 nm). About 50 betalains have been identified. The major betacyanin is betanin (Formula 9.14), glucoside of betanidin, which accounts for... 

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