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

Animal enzyme

Catechol-O-methyl transferase

O-methylated anthocyanidins

5-desoxy-malvidin
Capensinidin
Europinidin
Hirsutidin
Malvidin
Peonidin
Petunidin
Pulchellidin
Rosinidin
^[5]

O-methylated flavanols

Meciadanol (3-O'methyl catechin)

O-methylated flavanones

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

O-methylated flavones

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

O-methylated isoflavones

References

↑ 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.
↑ 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.
↑ 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.
↑ 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.
↑ 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.

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[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.

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