Eugenol acsv.svg
   HOME

TheInfoList



OR:

Eugenol is an
allyl In organic chemistry, an allyl group is a substituent with the structural formula , where R is the rest of the molecule. It consists of a methylene bridge () attached to a vinyl group (). The name is derived from the scientific name for garlic, ...
chain-substituted guaiacol, a member of the
allylbenzene Phenylpropene is the organic compound with the formula C6H5CH2CH=CH2. It is a colorless liquid. The compound consists of a phenyl group attached to allyl. Phenylpropene isomerizes to trans-propenylbenzene. In plant biochemistry, the phenylpro ...
class of chemical compounds. It is a colorless to pale yellow, aromatic oily liquid extracted from certain
essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...
s especially from
clove Cloves are the aromatic flower buds of a tree in the family Myrtaceae, ''Syzygium aromaticum'' (). They are native to the Maluku Islands (or Moluccas) in Indonesia, and are commonly used as a spice, flavoring or fragrance in consumer products, ...
, nutmeg,
cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakfa ...
, basil and
bay leaf The bay leaf is an aromatic leaf commonly used in cooking. It can be used whole, either dried or fresh, in which case it is removed from the dish before consumption, or less commonly used in ground form. It may come from several species of tr ...
. It is present in concentrations of 80–90% in clove bud oil and at 82–88% in clove leaf oil. Eugenol has a pleasant, spicy,
clove Cloves are the aromatic flower buds of a tree in the family Myrtaceae, ''Syzygium aromaticum'' (). They are native to the Maluku Islands (or Moluccas) in Indonesia, and are commonly used as a spice, flavoring or fragrance in consumer products, ...
-like scent. The name is derived from ''Eugenia caryophyllata'', the former Linnean nomenclature term for cloves. The currently accepted name is ''Syzygium aromaticum''.


Biosynthesis

The biosynthesis of eugenol begins with the amino acid tyrosine. L-tyrosine is converted to ''p''-coumaric acid by the enzyme
tyrosine ammonia lyase Tyrosine ammonia lyase (EC 4.3.1.23, L-tyrosine ammonia-lyase, TAL or Tyrase) is an enzyme in the natural phenols biosynthesis pathway. It transforms L-tyrosine into ''p''-coumaric acid. :  \xrightarrow  + Ammonia + H+ L-tyrosine = ''tr ...
(TAL). From here, ''p''-coumaric acid is converted to caffeic acid by ''p''-coumarate 3-hydroxylase using oxygen and
NADPH Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NAD ...
. ''S''-Adenosyl methionine (SAM) is then used to methylate caffeic acid, forming ferulic acid, which is in turn converted to feruloyl- CoA by the enzyme 4-hydroxycinnamoyl-CoA ligase (4CL). Next, feruloyl-CoA is reduced to coniferaldehyde by cinnamoyl-CoA reductase (CCR). Coniferaldeyhyde is then further reduced to coniferyl alcohol by cinnamyl-alcohol dehydrogenase (CAD) or sinapyl-alcohol dehydrogenase (SAD). Coniferyl alcohol is then converted to an ester in the presence of the substrate CH3COSCoA, forming coniferyl acetate. Finally, coniferyl acetate is converted to eugenol via the enzyme eugenol synthase 1 and the use of NADPH.


Pharmacology

Eugenol and thymol possess general anesthetic properties. Like many other anesthetic agents, these 2-alkyl(oxy)phenols act as positive allosteric modulators of the GABAA receptor. Although eugenol and thymol are too toxic and not potent enough to be used clinically, these findings led to the development of 2-substituted phenol anesthetic drugs, including
propanidid Propanidid is an ultra short-acting phenylacetate general anesthetic. It was originally introduced by Bayer in 1963 but anaphylactic reaction Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid ...
(later withdrawn) and the widely used
propofol Propofol, marketed as Diprivan, among other names, is a short-acting medication that results in a decreased level of consciousness and a lack of memory for events. Its uses include the starting and maintenance of general anesthesia, sedation f ...
. Eugenol and the structurally similar
myristicin Myristicin is a naturally occurring compound found in common herbs and spices, the most well known being nutmeg. It is an insecticide, and has been shown to enhance the effectiveness of other insecticides in combination. Myristicin is also a pre ...
, have the common property of inhibiting MAO-A and MAO-B in vitro. In humans, complete excretion occurs within 24 hour and metabolites are mostly conjugates of eugenol.


Uses


Humans

Eugenol is used as a flavor or aroma ingredient in teas, meats, cakes, perfumes, cosmetics, flavorings, and
essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...
s. It is also used as a local antiseptic and anaesthetic. Eugenol can be combined with zinc oxide to form
zinc oxide eugenol Zinc oxide eugenol (ZOE) is a material created by the combination of zinc oxide and eugenol contained in oil of cloves. An acid-base reaction takes place with the formation of zinc eugenolate chelate. The reaction is catalysed by water and is acc ...
which has restorative and
prosthodontic Prosthodontics, also known as dental prosthetics or prosthetic dentistry, is the area of dentistry that focuses on dental prostheses. It is one of 12 dental specialties recognized by the American Dental Association (ADA), Royal College of Sur ...
applications in
dentistry Dentistry, also known as dental medicine and oral medicine, is the branch of medicine focused on the teeth, gums, and mouth. It consists of the study, diagnosis, prevention, management, and treatment of diseases, disorders, and conditions o ...
. For persons with a dry socket as a complication of tooth extraction, packing the dry socket with a eugenol-zinc oxide paste on iodoform gauze is effective for reducing acute pain. Eugenol-zinc oxide paste is also used for root canal sealing.


Insects and fish

It is attractive to males of various species of orchid bees, which apparently gather the chemical to synthesize pheromones; it is commonly used as bait to attract and collect these bees for study. It also attracts female
cucumber beetle Cucumber beetle is a common name given to members of two genera of beetles, ''Diabrotica'' and ''Acalymma'', both in the family Chrysomelidae. The adults can be found on cucurbits such as cucumbers and a variety of other plants. Many are no ...
s. Eugenol and isoeugenol, which both are floral volatile scent compounds, are catalyzed by a single type of enzyme in the genus '' Gymnadenia'' and the gene encoding for this enzyme is the first functionally characterized gene in these species. Eugenol is an ingredient in some
insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...
s. Clove oil is common as an anesthetic for use on aquarium fish as well as on wild fish when sampled for research and management purposes. Where readily available, it presents a humane method to euthanize sick and diseased fish either by direct overdose or to induce sleep before an overdose of eugenol.


Other

Eugenol is an ingredient in some
fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...
s and weed control products used in agricultural practices in the European Union. It is used in hundreds of household products, such as
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s, pet care,
laundry Laundry refers to the washing of clothing and other textiles, and, more broadly, their drying and ironing as well. Laundry has been part of history since humans began to wear clothes, so the methods by which different cultures have dealt with t ...
, cleaning, and paper or vehicle products.


Toxicity

Taken orally in high doses for chronic periods, eugenol may cause
liver toxicity Hepatotoxicity (from ''hepatic toxicity'') implies chemical-driven liver damage. Drug-induced liver injury is a cause of acute and chronic liver disease caused specifically by medications and the most common reason for a drug to be withdrawn fro ...
. An overdose is possible, causing a wide range of symptoms from blood in the urine, to
convulsion A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a s ...
s, diarrhea, nausea, unconsciousness, dizziness, rapid heart rate, or acute kidney injury. ''N''-acetylcysteine may be used to treat people with eugenol or clove oil overdose.


As an allergenic

Eugenol is subject to restrictions on its use in
perfumery Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. Th ...
as some people may become sensitised to it, however, the degree to which eugenol can cause an allergic reaction in humans is disputed. Eugenol is a component of balsam of Peru, to which some people are allergic. When eugenol is used in dental preparations such as surgical pastes, dental packing, and dental cement, it may cause
contact stomatitis Contact stomatitis is inflammation or pain of the oral mucosa caused by external stimuli. It is characterized by cutaneous lesions that may be located where the offending agent contacts the mucosa for a prolonged time. Oftentimes it presents in th ...
and allergic
cheilitis Cheilitis is a medical condition characterized by inflammation of the lips. The inflammation may include the perioral skin (the skin around the mouth), the vermilion border, or the labial mucosa. The skin and the vermilion border are more common ...
. The allergy can be discovered via a patch test.


Natural occurrence

Eugenol naturally occurs in numerous plants, including the following: *
Clove Cloves are the aromatic flower buds of a tree in the family Myrtaceae, ''Syzygium aromaticum'' (). They are native to the Maluku Islands (or Moluccas) in Indonesia, and are commonly used as a spice, flavoring or fragrance in consumer products, ...
s (''Syzygium aromaticum'') *
Wormwood Wormwood may refer to: Biology * Several plants of the genus ''Artemisia'': ** ''Artemisia abrotanum'', southern wormwood ** '' Artemisia absinthium'', common wormwood, grande wormwood or absinthe wormwood ** ''Artemisia annua'', sweet wormwood o ...
*
Cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakfa ...
* ''
Cinnamomum tamala ''Cinnamomum tamala'', Indian bay leaf'','' also known as tejpat'', ''tejapatta'','' Malabar leaf, Indian bark, Indian cassia, or malabathrum, is a tree in the family Lauraceae that is native to India, Bangladesh, Nepal, Bhutan, and China. It c ...
'' * Nutmeg (''Myristica fragrans'') * '' Ocimum basilicum'' (sweet basil) * '' Ocimum gratissimum'' (African basil) * ''
Ocimum tenuiflorum ''Ocimum tenuiflorum'', commonly known as holy basil, ''tulsi'' or ''tulasi'', is an aromatic perennial plant in the family Lamiaceae. It is native to the Indian subcontinent and widespread as a cultivated plant throughout the Southeast Asian ...
'' (syn. ''Ocimum sanctum'', tulsi or holy basil) *
Japanese star anise ''Illicium anisatum'', with common names Japanese star anise, Aniseed tree, and sacred Anise tree, known in Japan as , is a tree closely related to the Chinese star anise (''Illicium verum)''. Since it is highly toxic, the fruit is not edible ...
* Lemon balm * Dill * ''
Pimenta dioica Allspice, also known as Jamaica pepper, myrtle pepper, pimenta, or pimento, is the dried unripe berry of ''Pimenta dioica'', a midcanopy tree native to the Greater Antilles, southern Mexico, and Central America, now cultivated in many warm pa ...
'' (Allspice) * Vanilla * Bay laurel * Celery *
Ginger Ginger (''Zingiber officinale'') is a flowering plant whose rhizome, ginger root or ginger, is widely used as a spice A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices ...
*
Wood avens ''Geum urbanum'', also known as wood avens, herb Bennet, colewort and St. Benedict's herb (Latin ''herba benedicta''), is a perennial plant in the rose family (Rosaceae), which grows in shady places (such as woodland edges and near hedgerows) in ...


See also

*
Zinc oxide eugenol Zinc oxide eugenol (ZOE) is a material created by the combination of zinc oxide and eugenol contained in oil of cloves. An acid-base reaction takes place with the formation of zinc eugenolate chelate. The reaction is catalysed by water and is acc ...
* Pseudoisoeugenol * Isoeugenol *
Acetyleugenol Acetyleugenol is a phenylpropanoid compound found in cloves. It is the second in abundance to the related compound eugenol in certain extract preparations. Like eugenol, its found in several plants such as '' Acacia nilotica'' and ''Piper betle'' ...
* Ferulic acid


References

{{Transient receptor potential channel modulators Phenylpropenes Flavors Perfume ingredients Phenols Allyl compounds O-methylated natural phenols O-methylated phenylpropanoids