Biology: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.[2]
Flavanoids can possess chiral carbons. Methods of analysis should take this element into account[3] especially regarding bioactivity or enzyme stereospecificity.[4]
Enzymes
The biosynthesis of flavonoids involves several enzymes.
Backbone
- 4-Coumaroyl-CoA Template:Underoverset chalcone (naringenin chalcone)
- Naringenin chalcone Template:Underoverset flavanone (naringenin).
Path to cyanidin:
- flavanone Template:Underoverset 3'-hydroxyflavonoid (eriodictyol)
- eriodictyol Template:Underoverset dihydroflavonol (taxifolin)
- taxifolin Template:Underoverset leucocyanidin
- leucocyanidin Template:Underoverset cyanidin
Path to (–)-epicatechin:
- cyanidin Template:Underoverset (–)-epicatechin
Path to (+)-catechin:
- leucocyanidin Template:Underoverset (+)-catechin
Path to flavones:
Path to flavonols:
- dihydroflavonol Template:Underoverset flavonol
Path to 3-deoxyanthocyanidins:
- flavanone Template:Underoverset flavan-4-ol
- (Process analogous to taxifolin → cyanidin follows)
Methylation
Glycosylation
- Anthocyanidin 3-O-glucosyltransferase
- Flavone 7-O-beta-glucosyltransferase
- Flavone apiosyltransferase
- Flavonol-3-O-glucoside L-rhamnosyltransferase
- Flavonol 3-O-glucosyltransferase
Further acetylations
References
- ↑ 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.
- ↑ Liu, Weixin; Feng, Yi; Yu, Suhang; Fan, Zhengqi; Li, Xinlei; Li, Jiyuan; Yin, Hengfu (2021). "The Flavonoid Biosynthesis Network in Plants". International Journal of Molecular Sciences 22 (23). doi:10.3390/ijms222312824. PMID 34884627.
- ↑ Yáñez, Jaime A.; Andrews, Preston K.; Davies, Neal M. (April 2007). "Methods of analysis and separation of chiral flavonoids". Journal of Chromatography B 848 (2): 159–181. doi:10.1016/j.jchromb.2006.10.052. PMID 17113835. http://www.sciencedirect.com/science/article/pii/S1570023206008671.
- ↑ Trouillas, Patrick; Fagnère, Catherine; Lazzaroni, Roberto; Calliste, Claude; Marfak, Abdelghafour; Duroux, Jean-Luc (December 2004). "A theoretical study of the conformational behavior and electronic structure of taxifolin correlated with the free radical-scavenging activity". Food Chemistry 88 (4): 571–582. doi:10.1016/j.foodchem.2004.02.009. http://www.sciencedirect.com/science/article/pii/S0308814604001608.
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