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Publications - Cell and Metabolic Biology

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Publications

Kobayashi, N.; Schmidt, J.; Wray, V.; Schliemann, W.; Formation and occurrence of dopamine-derived betacyanins Phytochemistry 56, 429-436, (2001) DOI: 10.1016/S0031-9422(00)00383-6

In light of the fact that the main betaxanthin (miraxanthin V) and the major betacyanin (2-descarboxy-betanidin) in hairy root cultures of yellow beet (Beta vulgaris L.) are both dopamine-derived, the occurrence of similar structures for the minor betacyanins was also suggested. By HPLC comparison with the betacyanins obtained by dopamine administration to beet seedlings, enzymatic hydrolysis, LCMS and 1H NMR analyses, the minor betacyanins from hairy roots were identified as 2-descarboxy-betanin and its 6′-O-malonyl derivative. A short-term dopamine administration experiment with fodder beet seedlings revealed that the condensation step between 2-descarboxy-cyclo-Dopa and betalamic acid is the decisive reaction, followed by glucosylation and acylation. From these data a pathway for the biosynthesis of dopamine-derived betalains is proposed. Furthermore, the occurrence of these compounds in various cell and hairy root cultures as well as beet plants (Fodder and Garden Beet Group) is shown.
Publications

Kobayashi, N.; Schmidt, J.; Nimtz, M.; Wray, V.; Schliemann, W.; Betalains from Christmas cactus Phytochemistry 54, 419-426, (2000) DOI: 10.1016/S0031-9422(00)00129-1

The presence of 14 betalain pigments have been detected by their characteristic spectral properties in flower petals of Christmas cactus (Schlumbergera x buckleyi). Along with the known vulgaxanthin I, betalamic acid, betanin and phyllocactin (6′-O-malonylbetanin), the structure of a new phyllocactin-derived betacyanin was elucidated by various spectroscopic techniques and carbohydrate analyses as betanidin 5-O-(2′-O-β-D-apiofuranosyl-6′-O-malonyl)-β-D-glucopyranoside. Among the more complex betacyanins occurring in trace amounts, the presence of a new diacylated betacyanin {betanidin 5-O-[(5″-O-E-feruloyl)-2′-O-β-D-apiofuranosyl-6′-O-malonyl)]-β-D-glucopyranoside} has been ascertained. Furthermore, the accumulation of betalains during flower development and their pattern in different organs of the flower has been examined.
Publications

Schliemann, W.; Kobayashi, N.; Strack, D.; The Decisive Step in Betaxanthin Biosynthesis Is a Spontaneous Reaction Plant Physiol. 119, 1217-1232, (1999) DOI: 10.1104/pp.119.4.1217

Experiments were performed to confirm that the aldimine bond formation is a spontaneous reaction, because attempts to find an enzyme catalyzing the last decisive step in betaxanthin biosynthesis, the aldimine formation, failed. Feeding different amino acids to betalain-forming hairy root cultures of yellow beet (Beta vulgaris L. subsp. vulgaris“Golden Beet”) showed that all amino acids (S- andR-forms) led to the corresponding betaxanthins. We observed neither an amino acid specificity nor a stereoselectivity in this process. In addition, increasing the endogenous phenylalanine (Phe) level by feeding the Phe ammonia-lyase inhibitor 2-aminoindan 2-phosphonic acid yielded the Phe-derived betaxanthin. Feeding amino acids or 2-aminoindan 2-phosphonic acid to hypocotyls of fodder beet (B. vulgaris L. subsp. vulgaris“Altamo”) plants led to the same results. Furthermore, feeding cyclo-3-(3,4-dihydroxyphenyl)-alanine (cyclo-Dopa) to these hypocotyls resulted in betanidin formation, indicating that the decisive step in betacyanin formation proceeds spontaneously. Finally, feeding betalamic acid to broad bean (Vicia faba L.) seedlings, which are known to accumulate high levels of Dopa but do not synthesize betaxanthins, resulted in the formation of dopaxanthin. These results indicate that the condensation of betalamic acid with amino acids (possibly includingcyclo-Dopa or amines) in planta is a spontaneous, not an enzyme-catalyzed reaction.
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