ContaminantDB: Furan

Identification Taxonomy Biological Properties Physical Properties Toxicity Profile Spectra Concentrations Links References Targets (3)XML

Record Information

Version

1.0

Creation Date

2014-08-29 05:52:38 UTC

Update Date

2026-04-16 21:17:34 UTC

Accession Number

CHEM003163

Identification

Common Name

Furan

Class

Small Molecule

Description

Furan is a member of the class of compounds known as furans. These are molecules containing a heterocyclic organic group consisting of a five-membered aromatic ring with four carbon atoms and one oxygen. Furan is aromatic because one of the lone pairs of electrons on the oxygen atom is delocalized into the ring, creating a 4n+2 aromatic system similar to benzene. Because of the aromaticity, furan is flat and lacks discrete double bonds. Furan is a colourless, flammable, highly volatile liquid with a boiling point close to room temperature (31°C). It is soluble in common organic solvents, including alcohol, ether, and acetone, but is insoluble in water. It has a strong ethereal odour. Furan is found in heat-treated (e.g. cooked, roasted, baked, pasteurized, and sterilized) commercial foods and is produced through thermal degradation of natural food constituents (PMID: 22641279). It can be found in roasted coffee, instant coffee, and processed baby foods (PMID: 22641279). In particular, the highest furan levels can be detected in coffee, with mean values between 42 and 3 660 ng/g for brewed coffee and roasted coffee beans. Furan can also be detected at levels between 0.2 and 3.2 ng/g in infant formula, from 22 to 24 ng/g in baked beans, from 13 to 17 ng/g in meat products, and from 23 to 24 ng/g in soups. In soy sauce, furan is detectable at 27 ng/g (PMID: 26483883). Research has indicated that coffee made in espresso makers and, above all, coffee made from capsules, contains more furan than that made in traditional drip coffee makers, although the levels are still within safe health limits. Various pathways have been reported for the formation of furan: (1) thermal degradation and/or thermal rearrangement of carbohydrates in the presence of amino acids, (2) thermal degradation of certain amino acids (aspartic acid, threonine, α-alanine, serine, and cysteine), (3) oxidation of ascorbic acid at higher temperatures, and (4) oxidation of polyunsaturated fatty acids and carotenoids (PMID: 26483883). Several studies have reported that furan formation occurs to a large extent during the Maillard reaction. The Maillard reaction involves the thermal degradation and rearrangement of carbohydrates (i.e. non-enzymatic browning reactions during food processing and cooking). Reducing hexoses often go through the Maillard reaction in the presence of amino acids and produce reactive intermediates such as 1-deoxy- and 3-deoxyosones, aldotetrose, and 2-deoxy-3-keto-aldotetrose. 2-Deoxy-3-keto-aldotetrose typically goes through retro-aldol cleavage leading to 3-deoxyosone which undergoes α-dicarbonyl cleavage, followed by oxidation and decarboxylation to form 2-deoxyaldotetrose, which is a direct precursor of furan. In addition to the formation of furan via carbohydrate degradation, furan can also be formed through thermal degradation of certain amino acids. Specifically, the amino acids that can form acetaldehyde and glycolaldehyde can produce furan by aldol condensation and cyclization (PMID: 26483883). Furan is toxic and may be carcinogenic. In particular, furan is a potent hepatotoxin and hepatocarcinogen in rodents, causing hepatocellular adenomas and carcinomas in rats and mice, and high incidences of cholangiocarcinomas in rats at doses ≥ 2 mg/kg (PMID: 22641279).

Contaminant Sources

Clean Air Act Chemicals
HMDB Contaminants - Urine
HPV EPA Chemicals
IARC Carcinogens Group 2B
OSHA Hazardous Chemicals
STOFF IDENT Compounds
T3DB toxins
Tobacco Smoke Compounds
ToxCast & Tox21 Chemicals

Contaminant Type

Cigarette Toxin
Industrial/Workplace Toxin
Metabolite
Organic Compound
Solvent
Synthetic Compound

Chemical Structure

MOL SDF 3D-SDF PDB SMILES InChI View 3D Structure

Synonyms

Value	Source
1,4-Epoxy-1,3-butadiene	ChEBI
Divinylene oxide	ChEBI
Furane	ChEBI
Oxacyclopentadiene	ChEBI
Oxole	ChEBI
Tetrole	ChEBI
Furfuran	HMDB
Furfurane	HMDB

Chemical Formula

C₄H₄O

Average Molecular Mass

68.074 g/mol

Monoisotopic Mass

68.026 g/mol

CAS Registry Number

110-00-9

IUPAC Name

furan

Traditional Name

furan

SMILES

O1C=CC=C1

InChI Identifier

InChI=1S/C4H4O/c1-2-4-5-3-1/h1-4H

InChI Key

YLQBMQCUIZJEEH-UHFFFAOYSA-N

Chemical Taxonomy

Description

belongs to the class of organic compounds known as heteroaromatic compounds. Heteroaromatic compounds are compounds containing an aromatic ring where a carbon atom is linked to an hetero atom.

Kingdom

Organic compounds

Super Class

Organoheterocyclic compounds

Class

Heteroaromatic compounds

Sub Class

Not Available

Direct Parent

Heteroaromatic compounds

Alternative Parents

Substituents

Heteroaromatic compound
Furan
Oxacycle
Organic oxygen compound
Hydrocarbon derivative
Organooxygen compound
Aromatic heteromonocyclic compound

Molecular Framework

Aromatic heteromonocyclic compounds

External Descriptors

furans (CHEBI:35559 )
mancude organic heteromonocyclic parent (CHEBI:35559 )
monocyclic heteroarene (CHEBI:35559 )

Biological Properties

Status

Detected and Not Quantified

Origin

Exogenous

Cellular Locations

Cytoplasm
Extracellular

Biofluid Locations

Not Available

Tissue Locations

Not Available

Pathways

Not Available

Applications

Not Available

Biological Roles

Chemical Roles

Maillard reaction product

Physical Properties

State

Liquid

Appearance

Not Available

Experimental Properties

Property	Value
Melting Point	-85.6°C
Boiling Point	32°C (89.6°F)
Solubility	10 mg/mL at 25°C

Predicted Properties

Property	Value	Source
Water Solubility	15.9 g/L	ALOGPS
logP	1.24	ALOGPS
logP	1.11	ChemAxon
logS	-0.63	ALOGPS
pKa (Strongest Basic)	-2.9	ChemAxon
Physiological Charge	0	ChemAxon
Hydrogen Acceptor Count	0	ChemAxon
Hydrogen Donor Count	0	ChemAxon
Polar Surface Area	13.14 Å²	ChemAxon
Rotatable Bond Count	0	ChemAxon
Refractivity	18.57 m³·mol⁻¹	ChemAxon
Polarizability	6.68 Å³	ChemAxon
Number of Rings	1	ChemAxon
Bioavailability	1	ChemAxon
Rule of Five	Yes	ChemAxon
Ghose Filter	No	ChemAxon
Veber's Rule	Yes	ChemAxon
MDDR-like Rule	No	ChemAxon

Spectra

Spectrum Type	Description	Splash Key	View
GC-MS	GC-MS Spectrum - EI-B (Non-derivatized)	splash10-00kr-9000000000-4c50652f33a401ab3cae	Spectrum
GC-MS	GC-MS Spectrum - EI-B (Non-derivatized)	splash10-00kr-9000000000-d007e0256578ac930b22	Spectrum
GC-MS	GC-MS Spectrum - EI-B (Non-derivatized)	splash10-00kr-9000000000-4c50652f33a401ab3cae	Spectrum
GC-MS	GC-MS Spectrum - EI-B (Non-derivatized)	splash10-00kr-9000000000-d007e0256578ac930b22	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positive	Not Available	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Positive	splash10-014i-9000000000-511af11e910184693aa1	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Positive	splash10-014i-9000000000-fd05695071ee559e9be4	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Positive	splash10-014i-9000000000-208e5dd03db999e390ff	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Negative	splash10-014i-9000000000-351aa9d338efe69d31ef	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Negative	splash10-014i-9000000000-acebecda0e70274875b1	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Negative	splash10-014i-9000000000-1df91dbb0164452d0fd1	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Positive	splash10-014u-9000000000-41895048238024d76bc7	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Positive	splash10-00ku-9000000000-a223589b20bc67c79fe0	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Positive	splash10-0udr-9000000000-056962459138c52c54c8	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Negative	splash10-00kf-9000000000-983ab9ff6334b0b9a584	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Negative	splash10-00ke-9000000000-77469f3e4a080d7d3681	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Negative	splash10-00kg-9000000000-d4fe1a89a559171ed26a	Spectrum
MS	Mass Spectrum (Electron Ionization)	splash10-00kr-9000000000-3bddc12b5a8dd3ca188d	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum

Toxicity Profile

Route of Exposure

Not Available

Mechanism of Toxicity

Furan is a potent hepatotoxin and hepatocarcinogen in rodents, causing hepatocellular adenomas and carcinomas in rats and mice, and high incidences of cholangiocarcinomas in rats at doses ≥ 2 mg/kg bw. A genotoxic mode of action cannot be excluded for furan-induced tumor formation. Furan is metabolized by cytochrome P450 (CYP) enzymes, predominantly CYP2E1, to its major metabolite cis-2-butene-1,4-dial (BDA, maleic dialdehyde), a highly reactive electrophile identified as the key mediator of furan toxicity and carcinogenicity. Furan-mediated effects on glutathione (GSH) levels and cell viability can be suppressed by the CYP inhibitor 1-phenylimidazole and increased by pretreatment of rats with acetone (a CYP2E1-inducing agent), indicating that furan cytotoxicity depends on its metabolic activation. BDA has been shown to react with cellular nucleophiles such as GSH and amino acids and to cause cross-links between thiols and amino groups, giving rise to lactam and pyrrole derivatives. Furan reduced the percentage of DNA in the comet tail in turkey liver fetal hepatocytes. Furan was also shown to induce chromosomal aberrations and sister chromatid exchanges (SCEs) in Chinese hamster ovary (CHO) cells. A statistically significant increase of micronucleated cells was recently reported in the spleen of furan-treated mice. A reduction of percentage of DNA in comet tail in liver cells was observed following treatment of turkey fetuses in ovo. Exposure to furan at doses associated with increased tumor incidences initially causes hepatocellular necrosis, accompanied by inflammation and sustained regenerative proliferation of hepatocytes, which may present key events in furan-induced hepatocellular carcinogenicity. Subcapsular and centrilobular necrosis accompanied by markedly increased liver enzymes is the primary response to furan treatment. The involvement of inflammatory processes in furan toxicity is also reflected by increased expression of cytokines and other inflammation-associated genes, such as IFN-γ, IL-1β, IL-6, IL-10, and components of the complement system, which may, however, also derive from lesions involving the biliary tract. Indeed, increased production of reactive oxygen species in response to furan is suggested by immunohistochemical detection of 8-oxo-dG within nuclei of hepatocytes of centrilobular areas following high-dose exposure and changes in the expression of genes responsive to oxidative stress in rats and/or mice. (1)

Metabolism

Not Available

Toxicity Values

Not Available

Lethal Dose

Not Available

Carcinogenicity (IARC Classification)

2B, possibly carcinogenic to humans. (2)

Uses/Sources

Not Available

Minimum Risk Level

Not Available