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2013-10-29T16:06:46Z

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{{Chembox
| ImageFile = Acide 2,4-dihydroxycinnamique.svg
| ImageSize = 200px
| ImageAlt = Chemical structure of umbellic acid
| IUPACName = (''E'')-3-(2,4-dihydroxyphenyl)prop-2-enoic acid
| OtherNames = 2,4-Dihydroxycinnamic acid<br>(''E'')-2,4-Dihydroxycinnamic acid<br>(2''E'')-3-(2,4-Dihydroxyphenyl)acrylic acid
| Section1 = {{Chembox Identifiers
| CASNo = 614-86-8
| InChI = 1S/C9H8O4/c10-7-3-1-6(8(11)5-7)2-4-9(12)13/h1-5,10-11H,(H,12,13)/b4-2+
| InChIKey = HGEFWFBFQKWVMY-DUXPYHPUSA-N
| PubChem = 446611
| SMILES = C1=CC(=C(C=C1O)O)C=CC(=O)O
| ChemSpiderID = 393925
}}
| Section2 = {{Chembox Properties
| C=9|H=8|O=4
| ExactMass = 180.042259 u
| Appearance =
| Density =
| MeltingPt =
| BoilingPt =
| Solubility =
}}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| Autoignition =
}}
}}

'''Umbellic acid''' ('''2,4-dihydroxycinnamic acid''') is a hydroxycinnamic acid. It is an isomer of [[caffeic acid]].

It is a precursor in the [[umbelliferone]] biosynthesis pathway. Umbelliferone is a [[phenylpropanoid]] and as such is synthesized from [[phenylalanine|<small>L</small>-phenylalanine]], which in turn is produced via the shikimate pathway. Phenylalanine is lysated into [[cinnamic acid]], followed by [[hydroxylation]] by [[cinnamate 4-hydroxylase]] to yield [[4-coumaric acid]]. The 4-coumaric acid is again hydroxylated by cinnamate/coumarate 2-hydroxylase to yield 2,4-dihydroxy-cinnamic acid followed by a bond rotation of the unsaturated bond adjacent to the [[carboxylic acid]] group. Finally an intramolecular attack from the hydroxyl group of C2' to the carboxylic acid group closes the ring and forms the [[lactone]] umbelliferone.

: [[Image:L-Phenylalanin - L-Phenylalanine.svg|120px|L-phenylalanine]]  <math>\xrightarrow{PAL}</math> [[Image:Zimtsäure - Cinnamic acid.svg|120px|Cinnamic acid]] <math>\xrightarrow{C4H}</math> [[Image:Coumaric acid acsv.svg|140px|para-Coumaric acid]] <math>\xrightarrow{C2H}</math> [[Image:Acide 2,4-dihydroxycinnamique.svg|140px|2,4-Dihydroxycinnamic acid]] <math>\longrightarrow</math> [[File:Umbelliferone.svg|120px|Umbelliferone]]

The enzyme [[4-hydroxycinnamate decarboxylase]], induced in bacteria species such as ''[[Klebsiella oxytoca]]'', works also with p-coumaric acid analogs such as E-2,4-dihydroxycinnamic acid.<ref>{{cite journal | pmid = 11826954 | year = 2001 | last1 = Hashidoko | first1 = Y | last2 = Tanaka | first2 = T | last3 = Tahara | first3 = S | title = Induction of 4-hydroxycinnamate decarboxylase in Klebsiella oxytoca cells exposed to substrates and non-substrate 4-hydroxycinnamate analogs | volume = 65 | issue = 12 | pages = 2604–12 | journal = Bioscience, biotechnology, and biochemistry}}</ref>

== References ==
{{Reflist}}

== External links ==
{{wiktionary inline|umbellic acid}}

{{Hydroxycinnamic acid}}

[[Category:Hydroxycinnamic acids]]

{{natural phenol-stub}}

Transition rate matrix - Revision history

en>Gareth Jones: use cite doi template for reference