Phenylpropanoids metabolism

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The biosynthesis of phenylpropanoids involves a number of enzymes.

From amino acids to cinnamates[edit]

In plants, all phenylpropanoids are derived from the amino acids phenylalanine and tyrosine.

Phenylalanine ammonia-lyase (PAL, a.k.a. phenylalanine/tyrosine ammonia-lyase) is an enzyme that transforms L-phenylalanine and tyrosine into trans-cinnamic acid and p-coumaric acid, respectively.

Trans-cinnamate 4-monooxygenase (cinnamate 4-hydroxylase) is the enzyme that transforms trans-cinnamate into 4-hydroxycinnamate (p-coumaric acid). 4-Coumarate-CoA ligase is the enzyme that transforms 4-coumarate (p-coumaric acid) into 4-coumaroyl-CoA.[1]

Biosynthesis of 4-hydroxycinnamoyl-CoA.png

Enzymes associated with biosynthesis of hydroxycinnamic acids[edit]

Conjugation enzymes[edit]

These enzymes conjugate phenylpropanoids to other molecules.


Stilbenoids biosynthesis[edit]

An alternative bacterial ketosynthase-directed stilbenoids biosynthesis pathway exists in Photorhabdus bacterial symbionts of Heterorhabditis nematodes, producing 3,5-dihydroxy-4-isopropyl-trans-stilbene for antibiotic purposes.[2]

Coumarins biosynthesis[edit]

Chalcones biosynthesis[edit]

4-Coumaroyl-CoA can be combined with malonyl-CoA to yield the true backbone of flavonoids, a group of compounds called chalconoids, which contain two phenyl rings. Naringenin-chalcone synthase is an enzyme that catalyzes the following conversion:

3-malonyl-CoA + 4-coumaroyl-CoA → 4 CoA + naringenin chalcone + 3 CO2

Flavonoids biosynthesis[edit]

Conjugate ring-closure of chalcones results in the familiar form of flavonoids, the three-ringed structure of a flavone.


Hydroxycinnamic acids degradation[edit]


  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. ^ Joyce SA, Brachmann AO, Glazer I, Lango L, Schwär G, Clarke DJ, Bode HB (2008). "Bacterial biosynthesis of a multipotent stilbene". Angew Chem Int Ed Engl. 47 (10): 1942–5. CiteSeerX doi:10.1002/anie.200705148. PMID 18236486.