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Semi-synthesis of red beet betacyanin ethyl-esters by esterification

Tuwalska D., Starzak K., Szot D., Wybraniec S., Winterhalter P., Jerz G.

Challenges of Modern Technology

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2014

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Vol. 5, no. 3

27--31

EN

Red beet pigments recovered from Beta vulgaris L. (Chenopodiaceae), mainly consist of purple betacyanins, such as 15R/15S-betanin. Currently,this pigment class is intensively investigated in respect of stability in food systems. Quite popular is the use of red beet extracts in dairy products such as yoghurts, and ice-creams. So far, there are no issues of toxicity using these natural pigments in food – so they seem to be a very good alternative to replace synthetic dyes which had been frequently discussed for negative side-effects to human health. Betacyanins, the glycosidation products of betanidin are very polar and therefore water soluble pigments, which are biosynthetically derived from condensation of cyclo-DOPA and betalamic acid. The significant polarity of betacyanins requires the use of ion-pair reagents such as trifluoro-acetic acid (TFA) or other homologue fluorinated additives under standard separation conditions on larger scale in spiral coil countercurrent chromatography (spCCC). In our synthetic experiment, the polarity of the natural betacyanins was reduced. This omitted the use of toxic per-fluoro ion-pair reagents. The three carboxylic groups of the betanin pigment backbone were the target functional groups of the derivatisation. In semi-synthesis, fortified red beet pigment extract was esterified with water-free ethanolic hydrogen chloride solution. The reaction was carried out at ambient temperature (7 days) to yield a mixture of betacyanin mono-, di- and tri-ethyl-esters, and their epimeric forms, as well as the respective betanidin-ethyl-esters. The time course of the reaction mixture was monitored by analytical C18-HPLC with ESI-DAD-MS/MS detection. The detected molecular weights of the pigments confirmed the presence of expected products. To the best of our knowledge, the presence of betalains containing ethyl-ester groups in biological samples have not been studied before.

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Stability of Betanidin Influenced by Copper Cations

Tuwalska D., Starzak K., Szot D., Skopińska A., Wybraniec S.

Logistyka

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2013

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nr 4

EN

Latest studies revealed some antioxidant properties of betalain pigments that contribute to the growth of interest in these compounds. During the isolation and storage, betalains are exposed to many different chemical and physical degradative factors, which often lead to their decomposition and discoloration. An effect of copper cations on betanidin stability was investigated in aqueous and organic-aqueous solutions. Betanidin stability experiments were performed at different pH’s, with different concentrations of metal cations and in different solvents. Using the modern spectrophotometric microplate reader it was possible to monitor changes of absorption spectra of the pigment samples during their incubation with copper ions in parallel at various physico-chemical conditions. Incubation with copper cations leads to betanidin degradation in all investigated solvents in the whole range of pH. The formed products are its new oxidized derivatives. A possibility of a formation of metal-pigment complexes is also considered. Recognition of betalains degradation paths is important because of their not yet fully recognized antioxidant and chemopreventive properties.

PL

Ostatnie badania wykazały przeciwutleniające właściwości betalain, co przyczyniło się do wzrostu zainteresowania tą grupą związków. Podczas izolacji i przechowywania, betalainy są narażone na wiele różnych degradujących czynników, chemicznych i fizycznych, które często powodują ich rozkład i odbarwienie. Zbadano wpływ kationów miedzi na stabilność betanidyny w roztworach wodnych i wodno-organicznych. Eksperymenty były przeprowadzane w różnym pH, z różnymi stężeniami kationów metalu i rozpuszczalników organicznych. Zastosowanie nowoczesnego spektrofotometrycznego czytnika mikropłytek pozwoliło na monitorowanie zmian w widmie absorpcyjnym pigmentu w różnych warunkach fizyko-chemicznych. Inkubacja betanidyny z jonami miedzi prowadzi do jej degradacji we wszystkich badanych rozpuszczalnikach w całym zakresie pH. Powstałe produkty są jej nowymi, utlenionymi pochodnymi. Rozważano również powstawanie kompleksu metal-pigment.Poznanie szlaków utleniania betalain jest ważne z powodu nie w pełni jeszcze poznanych ich antyutleniających i chemoprewencyjnych właściwości.

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Spiral-coil countercurrent chromatographic separation of betanin and betanidin ethyl-esters monitored by continuous ESI-MS/MS injection and LC-ESI-MS/MS

Tuwalska D., Szot D., Wybraniec S., Winterhalter P., Jerz G.

Challenges of Modern Technology

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2013

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Vol. 4, no. 4

21--25

EN

Betalains present in Beta vulgaris L. (Chenopodiaceae) have a high potential as natural pigments for food applications. They have been used as a substitute of synthetic dyes in processing of gelatine, strawberry yogurts, ice creams, fruits cocktails, candies and biscuits. The stability of betalains is strongly influenced by numerous factors – sugar content, and impact of light, oxygen, water activity, pH and temperature. A mixture of betacyanin mono-, di- and tri-ethyl-esters was separated by a large-volume spiral-coil countercurrent chromatography (spCCC) prototype which yielded fractions continuously off-line injected to anÂ ESI-MS/MS device. This method yielded a reconstituted pigment profile and finally enabled the MS-target-guided isolation procedure for the whole spCCC-experiment. The individual fractions were analyzed by LC/ESI-MS/MS. Betanin and betanidin mono-, di- and tri-ethyl-esters as well as other decarboxylated derivatives were detected in the chromatograms. The ethyl-esters of betanin were only partially fractionated, but clearly fractionated from the ethyl-esters of betanidin which will be of great value for biological evaluations.

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Research on betanidin oxidation by ABTS radicals

Starzak K., Skopińska A., Wybraniec S.

Challenges of Modern Technology

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2012

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Vol. 3, no. 4

39--43

EN

Betanidin is a basic betacyanin with 5,6-dihydroxyl moiety which causes its high antioxidant activity. It belongs to betalains, a group of natural, water-soluble plant pigments, which elicit a red-violet coloration of fruits and fl owers. One of the most popular sources of betanidin is red beet root (Beta vulgaris L.). Recent studies have shown importance of betalains oxidation, because of their high natural, antiradical and antioxidant activity and potential benefi ts for human health [1]. An eff ect of oxidation of betanidin using ABTS radicals was investigated in aqueous solutions at pH 3–8 and compared to activity of horseradish peroxidase. Products of the biomimetic betanidin oxidation were monitored by high performance liquid chromatography (HPLC) coupled to optical detection and mass spectrometry (LC-DAD-ESI-MS/MS). The presence of two main oxidation products: 2-decarboxy-2,3-dehydro-betanidin and 2,17-didecarboxy-2,3-dehydro- -betanidin at pH 3 indicates their generation through two possible reaction ways with two diff erent quinonoid intermediates: dopachrome derivative and quinone methide. Both reaction paths lead to the decarboxylative dehydrogenation of betanidin.