O-methylated flavonoid

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.^[1] Those enzymes mediate the O-methylation on a specific hydroxyl group, like on 4' (example in Catharanthus roseus^[2]) or 3' (example in rice^[3]) 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.^[4]

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-methylted anthocyanidins

• 5-desoxy-malvidin
• capensinidin
• europinidin
• hirsutidin
• malvidin
• Peonidin
• Petunidin
• pulchellidin
• Rosinidin

.^[5]

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
• Nepetin
• Nobiletin
• Oroxylin-A
• Sinensetin
• Tangeritin
• 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. ^ Regiospecific methylation of naringenin to ponciretin by soybean O-methyltransferase expressed in Escherichia coli. Dae Hwan Kim, Kim Bong-Gyu, Lee Youngshim, Ji Young Ryu, Lim Yoongho, Hur Hor-Gil and Ahn Joong-Hoon, Journal of biotechnology, 2005, vol. 119, no2, pp. 155-162
2. ^ Flavonoid methylation: a novel 4′-O-methyltransferase from Catharanthus roseus, and evidence that partially methylated flavanones are substrates of four different flavonoid dioxygenases. Gudrun Schrödera, Elke Wehinger, Richard Luka, Frank Wellmann, Wallburga Seefelder, Wilfried Schwab and Joachim Schröder, Phytochemistry, Volume 65, Issue 8, April 2004, Pages 1085-1094
3. ^ Flavonoid 3′-O-methyltransferase from rice: cDNA cloning, characterization and functional expression. Bong-Gyu Kima, Youngshim Leea, Hor-Gil Hurb, Yoongho Lima and Joong-Hoon Ahn, Phytochemistry, Volume 67, Issue 4, February 2006, Pages 387-394
4. ^ O-methylation of flavonoids by cell-free extracts of calamondin orange. Gunter Brunet and Ragai K. Ibrahim, Phytochemistry, Volume 19, Issue 5, 1980, Pages 741-746
5. ^ Comparative biochemistry of the flavonoids-IV. *1: Correlations between chemistry, pollen morphology and systematics in the family plumbaginaceae. J. B. Harborne. 1967