Dehydrogenation of Betacyanins in Heated Betalain-Rich Extracts of Red Beet (Beta vulgaris L.)

Abstract

Betacyanins are a group of water-soluble red-violet compounds containing nitrogen in their structure. These are biosynthesized in red beetroot (Beta vulgaris L.), a widely consumed vegetable that contains significant amounts of nutritious and bioactive compounds which are also found in dietary supplements. This contribution presents results of betacyanin thermal oxidation (resulting in dehydrogenation) interrelated with decarboxylation in selected acetate/phosphate buffers at pH 3–8 and at 85 °C, which may be of particular significance for formulation and performance of foods. Most of the reaction products were detected at the highest concentrations in the acidic solutions (pH 3–4). The main dehydrogenation reaction pathways were monitored by LC-DAD-MS/MS and were associated with decarboxylation of the principal extract pigments, betanin/isobetanin and neobetanin, at carbon positions C-2 and C-17. Additional reactions are accompanied by the 2,15-decarboxylation processes at different dehydrogenation levels with 15-decarboxy-betanin and 2,15-bidecarboxy-betanin, structurally elucidated by NMR analysis, as the distinct indicators of this route type. For other novel pigments detected, 2,15-bidecarboxy-xanbetanin, 2,15-bidecarboxy-xanneobetanin and 2,15,17-tridecarboxy-neobetanin, additional high resolution mass spectrometric analyses were performed and confirmed their molecular formulas.

Antioxidant Capacity, Antitumor Activity and Metabolomic Profile of a Beetroot Peel Flour

“…These molecules have antioxidant potential that is well-reported on in the literature. However, some bioactive compounds in beetroot are thermally sensitive and can degrade during processing [ 11 , 33 ]. Thus, the BPF extracts were analyzed using different in vitro methods.…”

“…However, the thermal processing of the BPF promoted modifications of the betalains present in the in natura beetroot, leading to the formation of decarboxylated betalain compounds [ 33 ], which were identified via UHPLC-HRMS in this study. 15,17-bidecarboxy-betanin and 2,15-bidecarboxy-xanbetanin are thermally degraded betalain forms, both metabolites of betanin, produced via different decarboxylation and oxidation (with the liberation of H 2 O) paths, and they are precursors of 2,15,17-tridecarboxy-xanneobetanin, as proposed by Sutor-Swiezy et al (2022) in their study of the thermal degradation of betalains [ 11 ]. In addition, another decarboxylated compound was found, and it was identified as 2,15,17-tridecarboxy-bidehydro-amaranthin [ 49 ].…”

“…For the targeted analysis, the samples were injected at a flow rate of 10 μL min −1 using a spray voltage of 3.6 kV in the positive ionization mode. The mass range evaluated was from m / z 100 to 1000 in order to discover the signals already described in the literature [ 11 , 25 , 26 ] for betalains and their derivatives. All the m / z signals within a mass accuracy of ±10 ppm were submitted to an MS 2 analysis in order to evaluate their fragmentation profile and to confirm the identification.…”

“…Extracts have obtained been from different parts of the beetroot plant, such as the flesh [ 8 ], leaves [ 2 ], roots [ 9 ] and peel [ 10 ], with betalains and polyphenols receiving great attention. Betalains have previously been reported not only as antioxidants [ 11 ] but also as molecular agents that act via different pathways, such as via the inhibition of the mTOR pathway, the positive modulation of the caspases pathway [ 12 ], and the activation of the p53 pathway [ 6 ], leading to the modulation of the cell cycle and apoptosis [ 13 ].…”

Effect of soil biostimulant application for the growth and quality of beet seedlings

“…The beet, Beta vulgaris L., which belongs to the Chenopodiaceae family, has a tuberous root with a globular shape that develops almost superficially in the soil, with a purple color coming from the natural pigment anthocyanin (De Resende and Cordeiro, 2007;Sutor-Świeży, et al, 2022). It is a predominant vegetable from temperate climates, developing better in mild or cold temperatures, around 10 to 20 o C (Souza and Resende, 2006;Lombardi et al, 2022).…”