Syntheses of Betalains

C. Syntheses of Betalains by Reaction of Betalamic Acid with Amino Acids... 

Scheme 4. Syntheses of betalains from betalamic acid derivative 66.

Betalains.—The dihydropyridine moiety of the betalains, e.g. betanin (177), has been shown to be generated from dopa, modification of which entails extra-diol cleavage of its aromatic ring. The general assumption that betalamic acid (176) is an intermediate in the biosynthesis of the dihydopyridine fragment of the betalains is supported by its isolation from betalain-synthesizing plants. ... 

Cetosia plumosa was selected for further studyof betalain biosynthesis as yellow varieties of this species showed, on administration of appropriate substrates, an ability to synthesize the red pigment amaranthin (189) normally produced by other varieties of the same species. The experimental work was thus simplified because in some cases it was not necessary to employ radioactive precursors the consequence of feeding a particular substrate could be correlated with the appearance of red pigment. 

Betalains are synthesized by hairy root cultures of Beta vulgaris. The alkaloids are not excreted into the medium (Flores et al., 1987). 

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