Template:Chembox Cinnamaldehyde is an organic compound with the formula Template:Chem2 or Template:Chem2. Occurring naturally as predominantly the trans (E) isomer, it gives cinnamon its flavor and odor.<ref name="GDV">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> It is a phenylpropanoid that is naturally synthesized by the shikimate pathway.<ref>Template:Cite book</ref> This pale yellow, viscous liquid occurs in the bark of cinnamon trees and other species of the genus Cinnamomum. It is an essential oil. The bark of cinnamon tree contains high concentrations of cinnamaldehyde.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Structure and synthesisEdit
Cinnamaldehyde was isolated from cinnamon essential oil in 1834 by Jean-Baptiste Dumas and Eugène-Melchior Péligot<ref>Template:Cite journal</ref> and synthesized in the laboratory by the Italian chemist Luigi Chiozza in 1854.<ref>Template:Cite journal</ref>
The natural product is trans-cinnamaldehyde. The molecule consists of a benzene ring attached to an unsaturated aldehyde. Cinnamaldehyde is an α,β-unsaturated carbonyl compound. Its color is due to the π → π* transition: increased conjugation in comparison with acrolein shifts this band towards the visible.<ref>Template:Cite journal</ref>
BiosynthesisEdit
Cinnamaldehyde is biosynthesized from phenylalanine.<ref>Template:Cite journal</ref> Deamination of L-phenylalanine into cinnamic acid is catalyzed by phenylalanine ammonia lyase (PAL).<ref name=":0">Template:Cite journal</ref><ref>Template:Cite journal</ref> PAL catalyzes this reaction by a non-oxidative deamination. This deamination relies on the MIO prosthetic group of PAL.<ref name=":1">Template:Cite journal</ref> PAL gives rise to trans-cinnamic acid. In the second step, 4-coumarate–CoA ligase (4CL) converts cinnamic acid to cinnamoyl-CoA by an acid–thiol ligation.<ref name=":0" /> 4CL uses ATP to catalyze the formation of cinnamoyl-CoA.<ref>Template:Cite journal</ref> 4CL effects this reaction in two steps.<ref>Template:Cite journal</ref> 4CL forms a hydroxycinnamate–AMP anhydride, followed by a nucleophile attack on the carbonyl of the acyl adenylate.<ref name=":3">Template:Cite journal</ref> Finally, Cinnamoyl-CoA is reduced by NADPH catalyzed by CCR (cinnamoyl-CoA reductase) to form cinnamaldehyde.<ref name=":0" /><ref>Template:Cite journal</ref>
PreparationEdit
Several methods of laboratory synthesis exist. The compound can be prepared from related compounds such as cinnamyl alcohol. An early synthesis involved the aldol condensation of benzaldehyde and acetaldehyde.<ref>Richmond, H. Preparation of Cinnamaldehyde. US Patent Application 2529186, November 7, 1950.</ref> Cinnamaldehyde can also be obtained from the steam distillation of the oil of cinnamon bark.
ApplicationsEdit
As a flavorantEdit
The most obvious application for cinnamaldehyde is as flavoring in chewing gum, ice cream, candy, e-liquid and beverages; use levels range from 9 to 4,900 parts per million (ppm) (that is, less than 0.5%). It is also used in some perfumes of natural, sweet, or fruity scents. Almond, apricot, butterscotch, and other aromas may partially employ the compound for their pleasant smells. Cinnamaldehyde can be used as a food adulterant; powdered beechnut husk aromatized with cinnamaldehyde can be marketed as powdered cinnamon.<ref name=Ullmann>Template:Cite book</ref> Some breakfast cereals contain as much as 187 ppm cinnamaldehyde.<ref name=":2">Template:Cite journal</ref>
As an agrichemicalEdit
Cinnamaldehyde has been tested as a safe and effective insecticide against mosquito larvae.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> A concentration of 29 ppm of cinnamaldehyde kills half of Aedes aegypti mosquito larvae in 24 hours.<ref name=pmid15237942>Template:Cite journal
- Template:Cite press release</ref> Trans-cinnamaldehyde works as a potent fumigant and practical repellant for adult mosquitos.<ref>Template:Cite journal</ref> It also has antibacterial and antifungal properties.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Miscellaneous usesEdit
Cinnamaldehyde is a corrosion inhibitor for steel and other alloys. It is believed to form a protective film on the metal surface.<ref>Template:Cite journal</ref>
DerivativesEdit
Numerous derivatives of cinnamaldehyde are commercially useful. Dihydrocinnamyl alcohol (3-phenylpropanol) occurs naturally but is produced by double hydrogenation of cinnamaldehyde. It has the fragrances of hyacinth and lilac. Cinnamyl alcohol similarly occurs naturally and has the odor of lilac but can be also produced starting from cinnamaldehyde.<ref>Template:Cite journal</ref> Dihydrocinnamaldehyde is produced by the selective hydrogenation of the alkene subunit. α-Amylcinnamaldehyde and α-hexylcinnamaldehyde are important commercial fragrances, but they are not prepared from cinnamaldehyde.<ref name=Ullmann/> Hydrogenation of cinnamaldehyde, if directed to the alkene, gives hydrocinnamaldehyde. Aldol condensation of cinnamaldehyde with acetone forms dicinnamalacetone, which is used as an indicator.
ToxicologyEdit
Cinnamaldehyde is used in agriculture because of its low toxicity, but it is a skin irritant.<ref>Template:Cite journal</ref> Cinnamaldehyde may cause allergic contact stomatitis in sensitised individuals, however allergy to the compound is believed to be uncommon.<ref>Template:Cite journal</ref>
Cinnamaldehyde can contain traces of styrene, which arises during storage or transport. Styrene especially forms in high humidity and high temperatures.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
DNA repairEdit
Cinnamaldehyde is a dietary antimutagen that effectively inhibits both induced and spontaneous mutations.<ref name = Shaughnessy2006>Template:Cite journal</ref> Experimental evidence indicates that cinnamaldehyde induces a type of DNA damage in the bacterium Escherichia coli and in human cells that elicits recombinational DNA repair that then reduces spontaneous mutations.<ref name = Shaughnessy2006/><ref>Template:Cite journal</ref> In mice, X-ray–induced chromosome aberrations were reduced when cinnamaldehyde was given orally to the mice after X-ray irradiation,<ref>Template:Cite journal</ref> perhaps due to cinnamaldehyde-stimulated DNA repair.
ReferencesEdit
External linksEdit
Template:Phenylpropanoids Template:Purine receptor modulators Template:Transient receptor potential channel modulators