Fagopyrin
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| IUPAC name
1,3,4,6,8,13-Hexahydroxy-10,11-dimethyl-2,5-di(piperidin-2-yl)fenantro[1,10,9,8-opqra]peryleen-7,14-dion
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3D model (JSmol)
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CompTox Dashboard (EPA)
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| Properties | |
| C40H34N2O8 | |
| Molar mass | 670.718 g·mol−1 |
| Appearance | Red pigment |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Fagopyrin is a phototoxic substance found in the flowers of buckwheat (Fagopyrum esculentum).[1] Their chemical structure contains a naphthodianthrone skeleton similar to that of hypericin.[2] After exposure, fagopyrin can cause sensitivity to light, also called fagopyrism, an itchy skin rash.[3]
History and occurrence
The substance was isolated from flowers of the red-flowering genotype of buckwheat in 1941, and its chemical structure, which is derived from hypericin, was first described in 1979.[4] Within the edible parts of the plant, it is found exclusively in the brown fruit husk of buckwheat grains.[5]
Fagopyrin is located almost exclusively in the cotyledons of the buckwheat herb.
Structure
Recent literature describes several variants of fagopyrin, referred to as fagopyrins A to F. They differ in methylation at positions C-10 and C-11 and contain piperidineyl or pyrrolidineyl residues at C-2 and C-5.[6]
Biosynthesis and properties
The biosynthetic precursor of fagopyrin is protofagopyrin. This proto-compound converts under the influence of light by cyclization into fagopyrin, which is lipophilic and cannot be extracted with water. The content of fagopyrin in tea preparations is generally below the detection limit (<0.01%).[7][8]
A solution of fagopyrin in pyridine exhibits a red color.[9]
References
- ^ Brockmann, Hans; Weber, Erhard; Sander, Elsbeth (1950). "Fagopyrin, ein photodynamischer Farbstoff aus Buchweizen (Fagopyrum esculentum)". Die Naturwissenschaften. 37 (2): 43. Bibcode:1950NW.....37...43B. doi:10.1007/BF00645366. S2CID 29975083.
- ^ Tavčar Benković, Eva; Žigon, Dušan; Friedrich, Miha; Plavec, Janez; Kreft, Samo (2014). "Isolation, analysis and structures of phototoxic fagopyrins from buckwheat". Food Chemistry. 143: 432–439. doi:10.1016/j.foodchem.2013.07.118. PMID 24054263.
- ^ Kreft, S.; Janeš, D.; Kreft, I. (2013). "The content of fagopyrin and polyphenols in common and tartary buckwheat sprouts". Acta Pharmaceutica. 63 (4): 553–60. doi:10.2478/acph-2013-0031. PMID 24451079.
- ^ Hornyák, Marta; Kula-Maximenko, Monika; Miszalski, Zbigniew; Nilsson, Anna; Andrén, Per E.; Göransson, Ulf; Slazak, Blazej (2025). "Distribution of photosensitive fagopyrin in buckwheat flowers and its potential biological relevance". Scientific Reports. 15 (1) 36279. Bibcode:2025NatSR..1536279H. doi:10.1038/s41598-025-20116-4. PMC 12533014. PMID 41102249.
- ^ Montag, Andreas (2023). Pflanzen und Haut Dermatologisch bedeutsame Abwehrstrategien der Pflanzen in Europa (in German). Springer-Verlag. p. 247. ISBN 978-3-662-63014-3.
- ^ Tavčar Benković, Eva; Žigon, Dušan; Friedrich, Miha; Plavec, Janez; Kreft, Samo (2014). "Isolation, analysis and structures of phototoxic fagopyrins from buckwheat". Food Chemistry. 143: 432–439. doi:10.1016/j.foodchem.2013.07.118. PMID 24054263.
- ^ Hänsel, Rudolf; Sticher, Otto (2006). Pharmakognosie - Phytopharmazie (in German). Springer-Verlag. p. 1216. ISBN 978-3-540-34281-6.
- ^ Tavcar, E.; Stojilkovski, K.; Kreft, S. (2011). "Fagopyrin and its derivatives in buckwheat (Fagopyrum sp.)". Planta Medica. 77 (12): PL65. Bibcode:2011PlMed..7782714T. doi:10.1055/s-0031-1282714.
- ^ Southon, Ian W.; Buckingham, John (1989). "Fagopyrin". Dictionary of Alkaloids (2nd ed.). CRC Press. p. 430. ISBN 978-0-412-24910-5.