Flavonoid biosynthesis

Flavonoids are synthesized by the phenylpropanoid metabolic pathway in which the amino acid phenylalanine is used to produce 4-coumaroyl-CoA.[1] This can be combined with malonyl-CoA to yield the true backbone of flavonoids, a group of compounds called chalcones, which contain two phenyl rings. Conjugate ring-closure of chalcones results in the familiar form of flavonoids, the three-ringed structure of a flavone. The metabolic pathway continues through a series of enzymatic modifications to yield flavanones → dihydroflavonols → anthocyanins. Along this pathway, many products can be formed, including the flavonols, flavan-3-ols, proanthocyanidins (tannins) and a host of other various polyphenolics.

Flavonoid Biosynthesis Diagrams

Biosynthesis of catechin

A biochemical diagram showing the class of flavonoids and their source in nature through various inter-related plant species.

Flavanoids can possess chiral carbons. Methods of analysis should take this element into account[2] especially regarding bioactivity or enzyme stereospecificity.[3]

## Contents

* 1 Enzymes
* 1.1 Methylation
* 1.2 Glycosylation
* 1.3 Further acetylations
* 2 References

## Enzymes

The biosynthesis of flavonoids involves several enzymes.

* Anthocyanidin reductase
* Chalcone isomerase
* Dihydrokaempferol 4-reductase
* Flavone synthase
* Flavonoid 3'-monooxygenase
* Flavonol synthase
* Flavanone 3-dioxygenase
* Flavanone 4-reductase
* Leucoanthocyanidin reductase
* Leucocyanidin oxygenase
* Naringenin-chalcone synthase

### Methylation

* Apigenin 4'-O-methyltransferase
* Luteolin O-methyltransferase
* Quercetin 3-O-methyltransferase

### Glycosylation

* Anthocyanidin 3-O-glucosyltransferase
* Flavone 7-O-beta-glucosyltransferase
* Flavone apiosyltransferase
* Flavonol-3-O-glucoside L-rhamnosyltransferase
* Flavonol 3-O-glucosyltransferase

### Further acetylations

* Isoflavone-7-O-beta-glucoside 6"-O-malonyltransferase

## References

1. ↑ Ververidis Filippos, F; Trantas Emmanouil; Douglas Carl; Vollmer Guenter; Kretzschmar Georg; Panopoulos Nickolas (October 2007). "Biotechnology of flavonoids and other phenylpropanoid-derived natural products. Part I: Chemical diversity, impacts on plant biology and human health". Biotechnology Journal 2 (10): 1214–34. doi:10.1002/biot.200700084. PMID 17935117.
2. ↑ Methods of analysis and separation of chiral flavonoids. Jaime A. Yáñeza, Preston K. Andrewsb and Neal M. Journal of Chromatography B, Volume 848, Issue 2, 1 April 2007, Pages 159-181
3. ↑ A theoretical study of the conformational behavior and electronic structure of taxifolin correlated with the free radical-scavenging activity. Patrick Trouillas, Catherine Fagnère, Roberto Lazzaroni, Claude Calliste, Abdelghafour Marfak and Jean-Luc Duroux, Food Chemistry, Volume 88, Issue 4, December 2004, Pages 571-582

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Types of flavonoids

Flavonoids|

| Anthoxanthins|

| Flavones|

* Apigenin, Chrysin, et.c.

|

Flavonols|

* Quercetin, Kaempferol, et.c.

Isoflavones|

* Daidzein, Genistein, Orobol et.c.

Neoflavonoids|

* Dalbergichromene

Flavans|

| Flavan|

* Luteoliflavan

|

Flavan-3-ols
(flavanols)|

* Catechin, Gallocatechol, et.c.

Flavan-4-ols
(flavanols)|

* Apiforol, Luteoforol, et.c.

Flavan-3,4-diols|

* Leucocyanidin, Leucodelphinidin, et.c.

Flavanones|

* Hesperidin
* Naringenin
* Eriodictyol

Flavanonols|

* Taxifolin
* Aromadendrin, et.c.

Anthocyanidins|

| 3-deoxyanthocyanidins|

* Cyanidin, Delphinidin, et.c.

|

3-hydroxyanthocyanidin|

* Apigeninidin, Guibourtinidin, et.c.

Aurones|

* Aureusidin
* Leptosidin

Chalcones|

| Chalcones|

* Butein, Isoliquiritigenin, et.c.

|

Dihydrochalcone|

* Phloretin

Miscellaneous|

* List of phytochemicals in food
* C-methylated flavonoids
* O-methylated flavonoids
* Furanoflavonoids
* Pyranoflavonoids
* Prenylflavonoids
* Methylenedioxy
* Castavinols

Flavonoid biosynthesis

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