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The O-methylated flavonoids or methoxyflavonoids are flavonoids with methylations on hydroxyl groups (methoxy bonds). O-methylation has an effect on the solubility of flavonoids.

Enzymes

O-methylated flavonoids formation implies the presence of specific O-methyltransferase (OMT) enzymes which accept a variety of substrates. Those enzymes mediate the O-methylation on a specific hydroxyl group, like on 4' (example in Catharanthus roseus) or 3' (example in rice) positions. Those positions can be ortho, meta, para and there can be a special 3-O-methyltransferase for the 3-OH position. Calamondin orange (Citrus mitis) exhibits all of those activities.

Plant enzymes

• Apigenin 4'-O-methyltransferase
• 8-hydroxyquercetin 8-O-methyltransferase
• Isoflavone 4'-O-methyltransferase
• Isoflavone 7-O-methyltransferase
• Isoliquiritigenin 2'-O-methyltransferase
• Isoorientin 3'-O-methyltransferase
• Kaempferol 4'-O-methyltransferase
• Luteolin O-methyltransferase
• Methylquercetagetin 6-O-methyltransferase
• 3-methylquercetin 7-O-methyltransferase
• Myricetin O-methyltransferase
• Quercetin 3-O-methyltransferase
• Vitexin 2"-O-rhamnoside 7-O-methyltransferase

Animal enzyme

• Catechol-O-methyl transferase

O-methylated anthocyanidins

• 5-Desoxy-malvidin
• Capensinidin
• Europinidin
• Hirsutidin
• Malvidin
• Peonidin
• Petunidin
• Pulchellidin
• Rosinidin

O-methylated flavanols

• Meciadanol (3-O'methyl catechin)

O-methylated flavanones

• Hesperetin
• Homoeriodictyol
• Isosakuranetin
• Sakuranetin
• Sterubin

O-methylated flavanonols

• Dihydrokaempferide

O-methylated flavonols

of kaempferol

• Kaempferide

of myricetin

• Annulatin
• Combretol
• Europetin
• Laricitrin (3'-O-Dimethylmyricetin)
• 5-O-methylmyricetin
• Syringetin (3',5'-O-Dimethylmyricetin)

of quercetin

• Ayanin
• Azaleatin
• Isorhamnetin
• Ombuin
• Pachypodol
• Retusin (quercetin-3,7,3',4'-tetramethyl ether)
• Rhamnazin
• Rhamnetin
• Tamarixetin

other

• Eupatolitin
• Natsudaidain

O-methylated flavones

• Acacetin
• Chrysoeriol
• Diosmetin
• Nepetin
• Nobiletin
• Oroxylin-A
• Sinensetin
• Tangeritin
• Thevetiaflavone
• Wogonin

O-methylated isoflavones

• Biochanin A
• Calycosin
• Formononetin
• Glycitein
• Irigenin
• 5-O-methylgenistein
• Pratensein
• Prunetin
• Psi-tectorigenin
• Retusin
• Tectorigenin

See also

• C-methylated flavonoid

References

1. Kim, Dae Hwan; Kim, Bong-Gyu; Lee, Youngshim; Ryu, Ji Young; Lim, Yoongho; Hur, Hor-Gil; Ahn, Joong-Hoon (2005). "Regiospecific methylation of naringenin to ponciretin by soybean O-methyltransferase expressed in Escherichia coli". Journal of Biotechnology. 119 (2): 155–62. doi:10.1016/j.jbiotec.2005.04.004. PMID 15961179.
2. Schroder, G; Wehinger, E; Lukacin, R; Wellmann, F; Seefelder, W; Schwab, W; Schröder, J (2004). "Flavonoid methylation: a novel 4′-O-methyltransferase from Catharanthus roseus, and evidence that partially methylated flavanones are substrates of four different flavonoid dioxygenases". Phytochemistry. 65 (8): 1085–94. doi:10.1016/j.phytochem.2004.02.010. PMID 15110688.
3. Kim, Bong-Gyu; Lee, Youngshim; Hur, Hor-Gil; Lim, Yoongho; Ahn, Joong-Hoon (2006). "Flavonoid 3′-O-methyltransferase from rice: CDNA cloning, characterization and functional expression". Phytochemistry. 67 (4): 387–94. doi:10.1016/j.phytochem.2005.11.022. PMID 16412485.
4. Brunet, Gunter; Ibrahim, Ragai K. (1980). "O-methylation of flavonoids by cell-free extracts of calamondin orange". Phytochemistry. 19 (5): 741–6. doi:10.1016/0031-9422(80)85102-8.
5. Harborne, J.B. (1967). "Comparative biochemistry of the flavonoids-IV.: Correlations between chemistry, pollen morphology and systematics in the family plumbaginaceae". Phytochemistry. 6 (10): 1415–28. doi:10.1016/S0031-9422(00)82884-8.

• O-methylated flavonoids
• O-methylation