Cinnamaldehyde is an aldehyde found in cinnamon bark in high concentrations. It's used as a flavor and medicine. Cinnamon bark is usually used medicinally in doses of 1-6 grams orally. 6 grams of cinnamon can contain from to 42 to 189 mg cinnamaldehyde. Cinnamon contains approximately 1 to 3.5 percent essential oil. The essential oil is approximately 70 to 90 percent cinnamaldehyde.

Metabolism in Humans

In vitro tests using human skin homogenates show that cinnamaldehyde is metabolized by aldehyde dehydrogenase (ALDH). This action is theorized to produce cinnamic acid, a known metabolite of cinnamaldehyde. Another known metabolite of cinnamaldehyde, cinnamic alcohol, was found to be converted back into cinnamaldehyde by the action of alcohol dehydrogenase (ADH).[7]

CYP2A6 Inhibition

Cinnamaldehyde was found to potently inhibit CYP2A6 in vitro.[10] This effect has not been verified in humans.

Glutathione Depletion

Cinnamaldehyde reacts spontaneously with glutathione, but it's metabolites cinnamic acid and cinnamyl alcohol do not. In vitro tests using rat hepatocytes found that cinnamaldehyde and cinnamyl alcohol deplete glutathione levels equally, although cinnamyl alcohol has a delayed effect. It's theorized that cinnamyl alcohol only depletes glutathione after conversion into cinnamaldehyde by the action of alcohol dehydrogenase (ADH), which accounts for it's delayed action. Cinnamaldehyde's metabolite cinnamic acid has no effect of glutathione depletion.[5]

Glutathione S-transferase Inhibition

Cinnamaldehyde was found to considerably reduce the action of glutathione S-transferase (GST) in rats in vivo.[6]

Xanthine Oxidase Inhibition

Cinnamaldehyde potently inhibits xanthine oxidase with an IC50 of 8.4 µg/mL in vitro and potently inhibits xanthine oxidase when given to mice orally.[3]

Aldose Reductase Inhibition

Cinnamaldehyde inhibited rat lens aldose reductase with an IC50 value of 0.003 mg/mL in vitro.[4]

Reactions With Alkaloids and Other Compounds

Like many common aldehydes cinnamaldehyde has been shown to condense with several amines without the need for a catalyst.

Adducts with Amino Acids

Cinnamaldehyde was found to form adducts with amino acids.

Adduct tests with amino acids performed by Wei, Xiong, Jiang, Zhang, and Wen produced 9 different cinnamaldehyde adducts by simply mixing cinnamaldehyde with different potassium salts of amino acids at room temperature, no catalyst was required. The 9 adducts were created using potassium glycinate, potassium alaninate, potassium valinate, potassium phenylalaninate, potassium leucinate, potassium glutmate, potassium asparaginate, potassium glutminate, and potassium methioninate. [9] In another test cinnamaldehyde was found to directly form an adduct with the amino acid cysteine, no catalyst was required.[2]

Potassium {(E)-[(2E)-3-phenyl-2-propen-1-ylidene]amino}acetate (ChemSpider ID: 58867888) is one of the 9 adducts created by Wei, Xiong, Jiang, Zhang, and Wen. It was created by simply mixing cinnamaldehyde with the amino acid salt potassium glycinate (the potassium salt of glycine).[9] This adduct is also known as CHEMBL3752982 on PubChem.

Cinnamaldehyde + Potassium Glycinate = CHEMBL3752982
cinnamaldehyde.png potassium-glycinate.png potassium_{(E)-[(2E)-3-phenyl-2-propen-1-ylidene]amino}acetate.png

Adduct with Dapsone

AC1MSDH81, is an adduct of cinnamaldehyde and the alkaloid dapsone2.[1]

The adduct AC1MSDH8 is a Schiff base. AC1MSDH8 has been formed by the condensation of 0.264 grams of the aldehyde cinnamaldehyde with 0.281 grams of the alkaloid dapsone in 20 ml ethanol for 5 min while stirring at 60° C forming the Schiff base AC1MSDH8 with a yield of 87%. While heat is used to speed up the reaction, no chemical catalyst is needed.[1]

Cinnamaldehyde + Dapsone = AC1MSDH8
cinnamaldehyde.png dapsone.png AC1MSDH8.png

Adduct with Glutathione

Cinnamaldehyde reacts spontaneously with reduced glutathione (GSH) without a catalyst producing the adduct 1'-(glutathion-S-yl)-dihydrocinnamaldehyde.[5]

Adduct with Phenylacetamide

Cinnamaldehyde forms the adduct cinnamylidene-bisphenylacetamide by simply mixing it with the amide phenylacetamide while heating. No catalyst is needed.[8]

Adduct with Acetamide

Cinnamaldehyde forms the adduct cinnamylidene-bisacetamide by simply mixing it with the amide acetamide while heating. No catalyst is needed.[8]


The oral LD50 for cinnamaldehyde is 2.22 to 3.4 g/kg for rats and mice (Opdyke, 1979).

Chemical Properties

PubChem Compound ID: 637511
Molecular Weight: 132.15922 [g/mol]
Molecular Formula: C9H8O
XLogP3: 1.9
IUPAC Name: (E)-3-phenylprop-2-enal
InChI: InChI=1S/C9H8O/c10-8-4-7-9-5-2-1-3-6-9/h1-8H/b7-4+
Canonical SMILES: C1=CC=C(C=C1)C=CC=O
Isomeric SMILES: C1=CC=C(C=C1)/C=C/C=O

See Also

1. Parviz Torabi, S. Zahra Sayyed-Alangi, Mohammad T. Baei and M. Noei
Preparation and Study the Spectroscopic Properties of (15E)-4-((4E)-4-((E)-3-Phenylallylideneamino) Phenylsulfonyl)-N-((E)-3 Phenylallidene) Benzenamine and (15E)-4-((4E)-4-((Z)-2-Bromo-3 Phenylallylideneamino) Phenylsulfonyl)-N-((Z)-2-Bromo-3 Phenylallidene) Benzenamine: as Schiff Bases; World Applied Sciences Journal 18 (7): 925-928, 2012; ISSN 1818-4952; IDOSI Publications, 2012; DOI: 10.5829/idosi.wasj.2012.18.07.1015 (Download Attached PDF Document)
2. Arthur D. Little
3. Essential oil from leaves of Cinnamomum osmophloeum acts as a xanthine oxidase inhibitor and reduces the serum uric acid levels in oxonate-induced mice.
Wang SY, Yang CW, Liao JW, Zhen WW, Chu FH, Chang ST. PubMed PMID: 18693097
4. Inhibitory activity of Cinnamomum cassia bark-derived component against rat lens aldose reductase.
Lee HS. PubMed PMID: 12553890
5. Studies on trans-cinnamaldehyde II: Mechanisms of cytotoxicity in rat isolated hepatocytes.
Swales NJ, Caldwell J. PubMed PMID: 20650180
6. Constituents of the essential oil of the Cinnamomum cassia stem bark and the biological properties.
Choi J, Lee KT, Ka H, Jung WT, Jung HJ, Park HJ. PubMed PMID: 11693543
7. Cinnamic compound metabolism in human skin and the role metabolism may play in determining relative sensitisation potency.
Cheung C, Hotchkiss SA, Pease CK. PubMed PMID: 12615359
8. The condensation of aldehydes with amides
Rup Kishore Mehra, Kantilal C. Pandya; 1938; DOI 10.1007/BF03045405; Print ISSN 0370-0089
9. The antimicrobial activities of the cinnamaldehyde adducts with amino acids.
Wei QY, Xiong JJ, Jiang H, Zhang C, Wen Ye. PubMed PMID: 21856030 DOI: 10.1016/j.ijfoodmicro.2011.07.034 (Download Attached PDF Document)
10. Inactivation of CYP2A6 by the Dietary Phenylpropanoid trans-Cinnamic Aldehyde (Cinnamaldehyde) and Estimation of Interactions with Nicotine and Letrozole
Jeannine Chan, Tyler Oshiro, Sarah Thomas, Allyson Higa, Stephen Black, Aleksandar Todorovic, Fawzy Elbarbry, and John P. Harrelson PMCID: [ PMC4810772]
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