Isolation, analysis and structures of phototoxic fagopyrins from buckwheat

Benković, Eva Tavčar; Žigon, Dušan; Friedrich, Miha; Plavec, Janez; Kreft, Samo

doi:10.1016/j.foodchem.2013.07.118

Cited by 31 publications

(24 citation statements)

References 27 publications

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“…In the UV−visible spectrum, the absorption maxima of all eight fagopyrins occur at 284, 329, 545, and 590 nm. 20,25 Fluorescence. Fagopyrins fluoresce orange to red under UV light at 366 nm.…”

Section: ■ Methodsmentioning

confidence: 99%

“…Fluorescence detection using an excitation wavelength of 330 nm and an emission wavelength of 590 nm is more sensitive than UV−vis detection. 20 Protofagopyrin Transformation. Many authors observed the transformation of "invisible" molecular forms, termed protofagopyrins (Figure 1), to "visible" fagopyrins upon excitation with light.…”

Section: ■ Methodsmentioning

confidence: 99%

“…The aforementioned isofagopyrin and pseudofagopyrin forms were not confirmed, but at least five additional structures are reported to be in need of elucidation. 20 Mass Spectrometric Analyses. The following fragments were observed in positive spectra of LC-MS TOF ESI analysis: 20 NMR Analyses.…”

Section: ■ Methodsmentioning

confidence: 99%

“…20 Mass Spectrometric Analyses. The following fragments were observed in positive spectra of LC-MS TOF ESI analysis: 20 NMR Analyses. The signals that were observed in the NMR spectrum of fagopyrins F, E, and A are presented in Table 2.…”

Section: ■ Methodsmentioning

confidence: 99%

“…However, an analytical system was used, which did not allow a sufficient quantity of fagopyrins to be obtained for weight determination. 20 We therefore recommend that the method be scaled up to allow preparative quantities of product to be isolated and to improve the resolution of the method. Many authors have reported difficulties in the solubilization of their dried, purified extracts.…”

Section: ■ Isolation Attemptsmentioning

confidence: 99%

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Fagopyrins and Protofagopyrins: Detection, Analysis, and Potential Phototoxicity in Buckwheat

Benković

Kreft

2015

J. Agric. Food Chem.

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Buckwheat contains many healthy nutrients, and its consumption is therefore increasing. Buckwheat also contains fluorescent phototoxic fagopyrins. A systematic review of fagopyrins and the phototoxicity of buckwheat found that reliable quantitative data on fagopyrin toxicity are not yet available. Generally, buckwheat seeds, flour, and teas are safe in normal amounts. Diets extensively composed of buckwheat sprouts, herbs, and particularly flowers or of fagopyrin-rich buckwheat extracts may cause fagopyrism. A reference standard is needed, as it would enable the accurate evaluation of fagopyrin content in buckwheat products and would allow proper testing of their as yet unknown physical, chemical, and biological characteristics.

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Section: ■ Methodsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Section: ■ Isolation Attemptsmentioning

confidence: 99%

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Fagopyrins and Protofagopyrins: Detection, Analysis, and Potential Phototoxicity in Buckwheat

Benković

Kreft

2015

J. Agric. Food Chem.

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Buckwheat

Bastida¹,

Llopis²,

Zieliński³

2019

Whole Grains and Their Bioactives

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Fagopyrins from Buckwheat Flowers: Structural and Stereochemical Characterization Through Combined NMR/CD Spectroscopy and Theoretical Calculations

Galbusera,

Lattuada,

Pinto

et al. 2024

Chemistry A European J

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Fagopyrins are phenantroperylenequinones present in the flowers of Fagopyrum esculentum (buckwheat) endowed with photodynamic activity. It has been reported that fagopyrin extracts actually contain a complex mixture of closely related compounds, differing only on the nature of the perylenequinone substituents. We report our systematic and detailed study on the chemical composition of fagopyrin extracts by a combination of preparative and analytical techniques. The combined use of 1H‐NMR and CD spectroscopy was found to be particularly suited to fully characterize all stereochemical aspects of the extracted fagopyrins. For the first time nine isomers have been structurally characterized and their stereochemistry fully elucidated. The presence of two different heterocyclic ring substituents, two stereogenic centers and the inherent axial chirality of the aromatic system provides a complex stereochemical relationships among isomers, thus giving account of the high level of molecular multiplicity found in the extract.

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Isolation, analysis and structures of phototoxic fagopyrins from buckwheat

Cited by 31 publications

References 27 publications

Fagopyrins and Protofagopyrins: Detection, Analysis, and Potential Phototoxicity in Buckwheat

Fagopyrins and Protofagopyrins: Detection, Analysis, and Potential Phototoxicity in Buckwheat

Buckwheat

Fagopyrins from Buckwheat Flowers: Structural and Stereochemical Characterization Through Combined NMR/CD Spectroscopy and Theoretical Calculations

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