P-Coumaric acid

p-Coumaric acid is an organic compound with the formula HOC₆H₄CH=CHCO₂H. It is one of the three isomers of hydroxycinnamic acid. It is a white solid that is only slightly soluble in water but very soluble in ethanol and diethyl ether.

p-Coumaric acid

Names
Preferred IUPAC name (2E)-3-(4-Hydroxyphenyl)prop-2-enoic acid
Other names (E)-3-(4-Hydroxyphenyl)-2-propenoic acid (E)-3-(4-Hydroxyphenyl)acrylic acid para-Coumaric acid 4-Hydroxycinnamic acid β-(4-Hydroxyphenyl)acrylic acid
Identifiers
CAS Number	501-98-4 Y
3D model (JSmol)	Interactive image Interactive image
Beilstein Reference	2207383
ChEBI	CHEBI:32374 Y
ChEMBL	ChEMBL66879 Y
ChemSpider	553148 Y
DrugBank	DB04066 Y
ECHA InfoCard	100.116.210
EC Number	231-000-0
Gmelin Reference	2245630
IUPHAR/BPS	5787
KEGG	C00811
PubChem CID	637542
UNII	IBS9D1EU3J
CompTox Dashboard (EPA)	DTXSID30901076
InChI InChI=1S/C9H8O3/c10-8-4-1-7(2-5-8)3-6-9(11)12/h1-6,10H,(H,11,12)/b6-3+ Y Key: NGSWKAQJJWESNS-ZZXKWVIFSA-N Y InChI=1/C9H8O3/c10-8-4-1-7(2-5-8)3-6-9(11)12/h1-6,10H,(H,11, 12)/b6-3+/f/h11H InChI=1/C9H8O3/c10-8-4-1-7(2-5-8)3-6-9(11)12/h1-6,10H,(H,11,12)/b6-3+ Key: NGSWKAQJJWESNS-ZZXKWVIFBJ
SMILES C1=CC(=CC=C1\C=C\C(=O)O)O c1cc(ccc1/C=C/C(=O)O)O
Properties
Chemical formula	C9H8O3
Molar mass	164.160 g·mol−1
Melting point	210 to 213 °C (410 to 415 °F; 483 to 486 K)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H302, H311, H314, H315, H317, H319, H335
Precautionary statements	P260, P261, P264, P270, P271, P272, P280, P301+P310, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P332+P313, P333+P313, P337+P313, P361, P362, P363, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Natural occurrences

It is a precursor to many natural products, especially lignols, precursors to the woody mass that comprise many plants.^[1] Of the myriad occurrences, p-coumaric acid can be found in Gnetum cleistostachyum.^[2]

In food

p-Coumaric acid can be found in a wide variety of edible plants and fungi such as peanuts, navy beans, tomatoes, carrots, basil and garlic.^{[citation needed]} It is found in wine and vinegar.^[3] It is also found in barley grain.^[4]

p-Coumaric acid from pollen is a constituent of honey.^[5]

Derivatives

p-Coumaric acid glucoside can also be found in commercial breads containing flaxseed.^[6] Diesters of p-coumaric acid can be found in carnauba wax.

Biosynthesis

It is biosynthesized from cinnamic acid by the action of the P450-dependent enzyme 4-cinnamic acid hydroxylase (C4H).

 ${\displaystyle {\begin{matrix}{}\\{\xrightarrow {\mathrm {C4H} }}\\{}\end{matrix}}}$ 

It is also produced from L-tyrosine by the action of tyrosine ammonia lyase (TAL).

 ${\displaystyle {\xrightarrow {\mathrm {TAL} }}}$  + NH₃ + H⁺

Biosynthetic building block

p-Coumaric acid is the precursor of 4-ethylphenol produced by the yeast Brettanomyces in wine. The enzyme cinnamate decarboxylase catalyzes the conversion of p-coumaric acid into 4-vinylphenol.^[7] Vinyl phenol reductase then catalyzes the reduction of 4-vinylphenol to 4-ethylphenol. Coumaric acid is sometimes added to microbiological media, enabling the positive identification of Brettanomyces by smell.

The conversion of p-coumaric acid to 4-ethyphenol by Brettanomyces

cis-p-Coumarate glucosyltransferase is an enzyme that uses uridine diphosphate glucose and cis-p-coumarate to produce 4′-O-β-D-glucosyl-cis-p-coumarate and uridine diphosphate (UDP). This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases.^[8]

Phloretic acid, found in the rumen of sheep fed with dried grass, is produced by hydrogenation of the 2-propenoic side chain of p-coumaric acid.^[9]

The enzyme, resveratrol synthase, also known as stilbene synthase, catalyzes the synthesis of resveratrol ultimately from a tetraketide derived from 4-coumaroyl CoA.^[10]

p-Coumaric acid is a cofactor of photoactive yellow proteins (PYP), a homologous group of proteins found in many eubacteria.^[11]

See also

• o-coumaric acid
• m-coumaric acid
• Coumarin
• Coumaroyl-Coenzyme A
• Ferulic acid
• Cinnamic acid
• Phenolic content in wine
• p-Coumaroylated anthocyanins

References

1. Wout Boerjan, John Ralph, Marie Baucher "Lignin Biosynthesis" Annu. Rev. Plant Biol. 2003, vol. 54, pp. 519–46. doi:10.1146/annurev.arplant.54.031902.134938
2. Yao CS, Lin M, Liu X, Wang YH (April 2005). "Stilbene derivatives from Gnetum cleistostachyum". Journal of Asian Natural Products Research. 7 (2): 131–7. doi:10.1080/10286020310001625102. PMID 15621615. S2CID 37661785.
3. Gálvez MC, Barroso CG, Pérez-Bustamante JA (1994). "Analysis of polyphenolic compounds of different vinegar samples". Zeitschrift für Lebensmittel-Untersuchung und -Forschung. 199: 29–31. doi:10.1007/BF01192948. S2CID 91784893.
4. Quinde-Axtell Z, Baik BK (December 2006). "Phenolic compounds of barley grain and their implication in food product discoloration". Journal of Agricultural and Food Chemistry. 54 (26): 9978–84. doi:10.1021/jf060974w. PMID 17177530.
5. Mao W, Schuler MA, Berenbaum MR (May 2013). "Honey constituents up-regulate detoxification and immunity genes in the western honey bee Apis mellifera". Proceedings of the National Academy of Sciences of the United States of America. 110 (22): 8842–6. Bibcode:2013PNAS..110.8842M. doi:10.1073/pnas.1303884110. PMC 3670375. PMID 23630255.
6. Strandås C, Kamal-Eldin A, Andersson R, Åman P (October 2008). "Phenolic glucosides in bread containing flaxseed". Food Chemistry. 110 (4): 997–9. doi:10.1016/j.foodchem.2008.02.088. PMID 26047292.
7. "Brettanomyces Monitoring by Analysis of 4-ethylphenol and 4-ethylguaiacol". etslabs.com. Archived from the original on 2008-02-19.
8. Rasmussen S, Rudolph H (1997). "Isolation, purification and characterization of UDP-glucose: cis-p-coumaric acid-β-D-glucosyltransferase from sphagnum fallax". Phytochemistry. 46 (3): 449–453. doi:10.1016/S0031-9422(97)00337-3.
9. Chesson A, Stewart CS, Wallace RJ (September 1982). "Influence of plant phenolic acids on growth and cellulolytic activity of rumen bacteria". Applied and Environmental Microbiology. 44 (3): 597–603. Bibcode:1982ApEnM..44..597C. doi:10.1128/aem.44.3.597-603.1982. PMC 242064. PMID 16346090.
10. Wang, Chuanhong; Zhi, Shuang; Liu, Changying; Xu, Fengxiang; Zhao, Aichun; Wang, Xiling; Ren, Yanhong; Li, Zhengang; Yu, Maode (2017). "Characterization of Stilbene Synthase Genes in Mulberry (Morus atropurpurea) and Metabolic Engineering for the Production of Resveratrol in Escherichia coli". Journal of Agricultural and Food Chemistry. 65 (8): 1659–1668. doi:10.1021/acs.jafc.6b05212. PMID 28168876.
11. Hoff WD, Düx P, Hård K, Devreese B, Nugteren-Roodzant IM, Crielaard W, Boelens R, Kaptein R, van Beeumen J, Hellingwerf KJ (November 1994). "Thiol ester-linked p-coumaric acid as a new photoactive prosthetic group in a protein with rhodopsin-like photochemistry". Biochemistry. 33 (47): 13959–62. doi:10.1021/bi00251a001. PMID 7947803.