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 (Tangeretin) 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