Cinnamaldehyde was isolated from cinnamon essential oil in 1834 byJean-Baptiste Dumas andEugène-Melchior Péligot[3] and synthesized in the laboratory by the Italian chemist Luigi Chiozza in 1854.[4] Synonyms for Cinnamaldehyde include 3-Phenyl-2-propenal, Cinnamic aldehyde, trans-Cinnamaldehyde, Cinnamal, Cinnamyl aldehyde, Cassia aldehyde, 3-Phenylacrolein, and β-Phenylacrolein.[5][6]
The natural product istrans-cinnamaldehyde. The molecule consists of a benzene ring attached to an unsaturated aldehyde. Cinnamaldehyde is anα,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.[7]
The molecule can be identified by characteristic spectroscopic signals. Infrared spectra show strong absorption bands near 1685 cm-1 (C=O stretch) and 1620 cm-1 (C=C stretch). In the proton nuclear magnetic resonance (1H NMR) spectrum, the aldehydic proton resonates around 9.6 ppm, while aromatic and vinyl protons appear between 6.3 and 7.6 ppm.[8][9]
Pathway for the biosynthesis oftrans-cinnamaldehyde.
Cinnamaldehyde is biosynthesized fromphenylalanine.[10]Deamination ofL-phenylalanine intocinnamic acid is catalyzed byphenylalanine ammonia lyase (PAL).[11][12] PAL catalyzes this reaction by a non-oxidative deamination. This deamination relies on the MIO prosthetic group of PAL.[13] PAL gives rise totrans-cinnamic acid. In the second step, 4-coumarate–CoA ligase (4CL) converts cinnamic acid to cinnamoyl-CoA by an acid–thiol ligation.[11] 4CL uses ATP to catalyze the formation of cinnamoyl-CoA.[14] 4CL effects this reaction in two steps.[15] 4CL forms a hydroxycinnamate–AMP anhydride, followed by a nucleophile attack on the carbonyl of the acyl adenylate.[16] Finally, Cinnamoyl-CoA is reduced by NADPH catalyzed by CCR (cinnamoyl-CoA reductase) to form cinnamaldehyde.[11][17]
Cinnamaldehyde is stable under dry, cool, and dark storage conditions but slowly oxidizes in air and light to form cinnamic acid and related degradation products. It is slightly soluble in water but miscible with organic solvents such as ethanol, ether, and chloroform.[19][20]
In addition to flavor and fragrance applications, cinnamaldehyde is used in small amounts as anatural preservative in cosmetic and personal care formulations. It exhibits mild antimicrobial and antioxidant activity that helps extend product shelf life.[30][31]
Numerous derivatives of cinnamaldehyde are commercially useful. Dihydrocinnamyl alcohol (3-phenylpropanol) occurs naturally but is produced by doublehydrogenation 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.[32] Dihydrocinnamaldehyde is produced by the selective hydrogenation of the alkene subunit. α-Amylcinnamaldehyde andα-hexylcinnamaldehyde are important commercial fragrances, but they are not prepared from cinnamaldehyde.[21] Hydrogenation of cinnamaldehyde, if directed to the alkene, giveshydrocinnamaldehyde. Aldol condensation of cinnamaldehyde withacetone formsdicinnamalacetone, which is used as an indicator.Cinnamonitrile can be produced by anelimination reaction of variousoximes derived from cinnamaldehyde.[33] It is used in fragrance products.[34]
Cinnamaldehyde is used in agriculture because of its low toxicity, but it is a skin irritant.[35] Cinnamaldehyde may cause allergic contact stomatitis in sensitised individuals, however allergy to the compound is believed to be uncommon.[36]
Cinnamaldehyde can contain traces ofstyrene, which arises during storage or transport. Styrene especially forms in high humidity and high temperatures.[37]
Cinnamaldehyde is a dietaryantimutagen that effectively inhibits both induced and spontaneousmutations.[38] Experimental evidence indicates that cinnamaldehyde induces a type ofDNA damage in the bacteriumEscherichia coli and in human cells that elicitsrecombinational DNA repair that then reduces spontaneous mutations.[38][39] In mice,X-ray–inducedchromosome aberrations were reduced when cinnamaldehyde was given orally to the mice after X-ray irradiation,[40] perhaps due to cinnamaldehyde-stimulatedDNA repair.
Cinnamaldehyde is a bioactive electrophile that activates the transient receptor potential ankyrin 1 (TRPA1) ion channel, a chemosensory receptor expressed in sensory neurons and in the gastrointestinal tract. TRPA1 detects pungent or irritant compounds such as those found in cinnamon, mustard oil, and clove, producing the characteristic warming or burning sensation associated with these spices.[41] In the gastrointestinal tract, TRPA1 activation by cinnamaldehyde influences the release of serotonin from enterochromaffin cells, linking chemical irritation with gut motility and sensory signaling.[42] Because of this interaction, dietary cinnamaldehyde and other TRPA1 agonists are being studied for their potential to modulate gut–brain communication, relieve symptoms of irritable bowel syndrome (IBS), and alter visceral pain perception in humans.[43]
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^Ma, W.-B.; Feng, J.-T.; Jiang, Z.-L.; Zhang, X. (2014). "Fumigant Activity of 6 Selected Essential Oil Compounds and Combined Effect of Methyl Salicylate Andtrans-Cinnamaldehyde AgainstCulex pipiens pallens".Journal of the American Mosquito Control Association.30 (3):199–203.doi:10.2987/14-6412R.1.PMID25843095.S2CID36621630.
^Shreaz, Sheikh; Wani, Waseem A.; Behbehani, Jawad M.; Raja, Vaseem; Irshad, Md; Karched, Maribasappa; Ali, Intzar; Siddiqi, Weqar A.; Hun, Lee Ting (July 2016). "Cinnamaldehyde and its derivatives, a novel class of antifungal agents".Fitoterapia.112:116–131.doi:10.1016/j.fitote.2016.05.016.ISSN1873-6971.PMID27259370.
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^Olsen, R. V.; Andersen, H. H.; Møller, H. G.; Eskelund, P. W.; Arendt-Nielsen, L (2014). "Somatosensory and vasomotor manifestations of individual and combined stimulation of TRPM8 and TRPA1 using topical L-menthol andtrans-cinnamaldehyde in healthy volunteers".European Journal of Pain.18 (9):1333–42.doi:10.1002/j.1532-2149.2014.494.x.PMID24664788.S2CID34286049.
^Isaac-Renton, Megan; Li, Monica Kayi; Parsons, Laurie M. (May 2015). "Cinnamon spice and everything not nice: many features of intraoral allergy to cinnamic aldehyde".Dermatitis: Contact, Atopic, Occupational, Drug.26 (3):116–121.doi:10.1097/DER.0000000000000112.ISSN2162-5220.PMID25984687.
^Sasaki, Y. F.; Ohta, T.; Imanishi, H.; Watanabe, M.; Matsumoto, K.; Kato, T.; Shirasu, Y. (1990). "Suppressing effects of vanillin, cinnamaldehyde, and anisaldehyde on chromosome aberrations induced by X-rays in mice".Mutation Research.243 (4):299–302.doi:10.1016/0165-7992(90)90146-b.PMID2325694.
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