Anethole (also known as anise camphor) is an organic compound that is widely used as a flavoring substance. It is a derivative of

phenylpropene 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 phenylprop ...

, a type of aromatic compound that occurs widely in nature, in

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 in the class of

phenylpropanoid The phenylpropanoids are a diverse family of organic compounds that are synthesized by plants from the amino acids phenylalanine and tyrosine. Their name is derived from the six-carbon, aromatic phenyl group and the three-carbon propene tail of ...

organic compounds. It contributes a large component of the odor and flavor of

anise Anise (; '), also called aniseed or rarely anix is a flowering plant in the family Apiaceae native to Eurasia. The flavor and aroma of its seeds have similarities with some other spices and herbs, such as star anise, fennel, licorice, and ta ...

and fennel (both in the botanical family Apiaceae), anise myrtle (

Myrtaceae Myrtaceae, the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pōhutukawa, bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus are some notable members of this group. All speci ...

liquorice Liquorice (British English) or licorice (American English) ( ; also ) is the common name of ''Glycyrrhiza glabra'', a flowering plant of the bean family Fabaceae, from the root of which a sweet, aromatic flavouring can be extracted. The liqu ...

(

Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

), magnolia blossoms, and

star anise ''Illicium verum'' is a medium-sized evergreen tree native to northeast Vietnam and southwest China. A spice commonly called star anise, staranise, star anise seed, star aniseed, star of anise, Chinese star anise, or badian that closely resembl ...

( Schisandraceae). Closely related to anethole is its

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

estragole, abundant in tarragon ( Asteraceae) and basil (

Lamiaceae The Lamiaceae ( ) or Labiatae are a family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, savory ...

), that has a flavor reminiscent of anise. It is a colorless, fragrant, mildly volatile liquid. Anethole is only slightly soluble in water but exhibits high solubility in ethanol. This trait causes certain anise-flavored

liqueur A liqueur (; ; ) is an alcoholic drink composed of spirits (often rectified spirit) and additional flavorings such as sugar, fruits, herbs, and spices. Often served with or after dessert, they are typically heavily sweetened and un-aged beyond ...

s to become opaque when diluted with water; the ouzo effect.

Structure and production

Anethole is an aromatic, unsaturated ether related to lignols. It exists as both ''cis''–''trans'' isomers (see also ''E''–''Z'' notation), involving the double bond outside the ring. The more abundant isomer, and the one preferred for use, is the '' trans'' or ''E'' isomer. Like related compounds, anethole is poorly soluble in water. Historically, this property was used to detect adulteration in samples. Most anethole is obtained from turpentine-like extracts from trees. Of only minor commercial significance, anethole can also be isolated from essential oils. Currently Banwari Chemicals Pvt Ltd situated in Bhiwadi, Rajasthan, India is the leading manufacuterer of Anethole. It is prepared commercially from 4-methoxy

propiophenone Propiophenone (shorthand: benzoylethane or BzEt) is an aryl ketone. It is a colorless, sweet-smelling liquid that is insoluble in water, but miscible with organic solvents. It is used in the preparation of other compounds. Production Propiophenon ...

, which is prepared from anisole.

Uses

Flavoring

Anethole is distinctly sweet, measuring 13 times sweeter than

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...

. It is perceived as being pleasant to the taste even at higher concentrations. It is used in alcoholic drinks ouzo,

rakı Rakı or raki (, Turkish pronunciation: ) is an alcoholic drink made of twice-distilled grapes. It is the national drink of Turkey. It is also popular in other Balkan countries as an Apéritif and digestif, apéritif as well as in Kazakhstan. I ...

, anisette and

absinthe Absinthe (, ) is an anise-flavoured spirit derived from several plants, including the flowers and leaves of ''Artemisia absinthium'' ("grand wormwood"), together with green anise, sweet fennel, and other medicinal and culinary herbs. Historical ...

, among others. It is also used in seasoning and confectionery applications, oral hygiene products, and in small quantities in natural berry

flavor Flavor or flavour is either the sensory perception of taste or smell, or a flavoring in food that produces such perception. Flavor or flavour may also refer to: Science *Flavors (programming language), an early object-oriented extension to Lis ...

Precursor to other compounds

Because they

metabolize Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

anethole into several

aromatic chemical compound Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping ...

s, some bacteria are candidates for use in commercial

bioconversion Bioconversion, also known as ''biotransformation'', is the conversion of organic materials, such as plant or animal waste, into usable products or energy sources by biological processes or agents, such as certain microorganisms. One example is the i ...

of anethole to more valuable materials. Bacterial strains capable of using trans-anethole as the sole carbon source include JYR-1 ('' Pseudomonas putida'') and TA13 (''

Arthrobacter aurescens ''Paenarthrobacter aurescens'' is a bacterium species from the genus '' Paenarthrobacter ''. ''Paenarthrobacter aurescens'' produces nitrilase and L-N-carbamoylase. ''Paenarthrobacter aurescens'' has a low GC-content and has the ability to util ...

'').

Research

Antimicrobial and antifungal activity

Anethole has potent antimicrobial properties, against bacteria, yeasts, and fungi. Reported antibacterial properties include both bacteriostatic and

bactericidal A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on their ...

action against '' Salmonella enterica'' but not when used against ''Salmonella'' via a

fumigation Fumigation is a method of pest control or the removal of harmful micro-organisms by completely filling an area with gaseous pesticides—or fumigants—to suffocate or poison the pests within. It is used to control pests in buildings (s ...

method. Antifungal activity includes increasing the effectiveness of some other

phytochemical Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poisons ...

s (such as

polygodial Polygodial is chemical compound found in dorrigo pepper, mountain pepper, horopito, canelo, paracress, water-pepper, and '' Dendrodoris limbata''.M Jonassohn (1996)Sesquiterpenoid unsaturated dialdehydes - Structural properties that affect r ...

) against '' Saccharomyces cerevisiae'' and '' Candida albicans''; '' In vitro'', anethole has antihelmintic action on eggs and larvae of the sheep gastrointestinal

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

'' Haemonchus contortus''. Anethole also has nematicidal activity against the plant nematode '' Meloidogyne javanica'' in vitro and in pots of

cucumber seedlings Cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the Cucurbitaceae family that bears usually cylindrical fruits, which are used as culinary vegetables.

Insecticidal activity

Anethole also is a promising insecticide. Several essential oils consisting mostly of anethole have insecticidal action against larvae of the mosquito '' Ochlerotatus caspius'' and '' Aedes aegypti''. In a similar manner, anethole itself is effective against the

fungus gnat Fungus gnats are small, dark, short-lived gnats, of the families Sciaridae, Diadocidiidae, Ditomyiidae, Keroplatidae, Bolitophilidae, and Mycetophilidae (order Diptera); they comprise six of the seven families placed in the superfamily Sciaroide ...

''Lycoriella ingenua'' ( Sciaridae) and the

mold mite ''Tyrophagus putrescentiae'' is a cosmopolitan mite species. Together with the related species '' T. longior'', it is commonly referred to as the mould mite or the cheese mite. The name translates from Greek to something like "putrid cheese eater. ...

''Tyrophagus putrescentiae''. Against the mite, anethole is a slightly more effective

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 ...

than

DEET ''N'',''N''-Diethyl-''meta''-toluamide, also called DEET () or diethyltoluamide, is the most common active ingredient in insect repellents. It is a slightly yellow oil intended to be applied to the skin or to clothing and provides protection ag ...

, but anisaldehyde, a related natural compound that occurs with anethole in many essential oils, is 14 times more effective. The insecticidal action of anethole is greater as a fumigant than as a contact agent. ''trans''-Anethole is highly effective as a fumigant against the cockroach ''

Blattella germanica The German cockroach (''Blattella germanica''), colloquially known as the croton bug, is a species of small cockroach, typically about long. In color it varies from tan to almost black, and it has two dark, roughly parallel, streaks on the prono ...

'' and against adults of the

weevil Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. They b ...

s ''

Sitophilus oryzae ''Sitophilus'' is a genus of weevils in the tribe Litosomini. Some species are familiar as pests of stored grain, nut, or seed. Notable pest species include the rice weevil (''S. oryzae''), wheat weevil (''S. granarius''), and maize weevil (''S. ...

'', ''

Callosobruchus chinensis ''Callosobruchus chinensis'' is a common species of beetle found in the bean weevil subfamily, and is known to be a pest to many stored legumes. Although it is commonly known as the adzuki bean weevil it is in fact not a true weevil, belonging ins ...

'' and beetle ''

Lasioderma serricorne ''Lasioderma serricorne'', commonly known as the cigarette beetle, cigar beetle, or tobacco beetle, is an insect very similar in appearance to the drugstore beetle (''Stegobium paniceum'') and the common furniture beetle (''Anobium punctatum''). A ...

''. As well as an insect pesticide, anethole is an effective insect repellent against mosquitos.

Ouzo effect

Anethole is responsible for the " ouzo effect" (also "louche effect"), the spontaneous formation of a microemulsion that gives many alcoholic beverages containing anethole and water their cloudy appearance. Such a spontaneous microemulsion has many potential commercial applications in the food and pharmaceutical industries.

Precursor to illicit drugs

Anethole is an inexpensive chemical precursor for paramethoxyamphetamine (PMA), and is used in its clandestine manufacture. Anethole is present in the essential oil from guarana, which has psychoactive effects typically attributed to its caffeine content. The absence of PMA or any other known psychoactive derivative of anethole in human urine after ingestion of guarana leads to the conclusion that any psychoactive effect of guarana is not due to aminated anethole metabolites. Anethole is also present in

, a

liquor Liquor (or a spirit) is an alcoholic drink produced by distillation of grains, fruits, vegetables, or sugar, that have already gone through alcoholic fermentation. Other terms for liquor include: spirit drink, distilled beverage or hard ...

with a reputation for

psychoactive A psychoactive drug, psychopharmaceutical, psychoactive agent or psychotropic drug is a chemical substance, that changes functions of the nervous system, and results in alterations in perception, mood, consciousness, cognition or behavior. Th ...

effects; these effects, however, are attributed to ethanol. (See also thujone,

anethole dithione Anethole trithione, anetholtrithione, or anetholtrithion (Japanese Accepted Name, JAN) is a drug used in the treatment of dry mouth. It is listed in the U.S. National Cancer Institute's ''Dictionary of Cancer Terms'' as being studied in the treatme ...

(ADT), and

anethole trithione Anethole trithione, anetholtrithione, or anetholtrithion (JAN) is a drug used in the treatment of dry mouth. It is listed in the U.S. National Cancer Institute The National Cancer Institute (NCI) coordinates the United States National Cancer Pro ...

(ATT).)

Estrogen and prolactin

Anethole has estrogenic activity. It has been found to significantly increase uterine weight in immature female rats. Fennel, which contains anethole, has been found to have a galactagogue effect in animals. Anethole bears a structural resemblance to catecholamines like

dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...

and may displace dopamine from its receptors and thereby disinhibit prolactin secretion, which in turn may be responsible for the galactagogue effects.

Safety

In the USA, anethole is generally recognized as safe (GRAS). After a hiatus due to safety concerns, anethole was reaffirmed by Flavor and Extract Manufacturers Association (FEMA) as GRAS. The concerns related to liver toxicity and possible carcinogenic activity reported in

rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...

s. Anethole is associated with a slight increase in

liver cancer Liver cancer (also known as hepatic cancer, primary hepatic cancer, or primary hepatic malignancy) is cancer that starts in the liver. Liver cancer can be primary (starts in liver) or secondary (meaning cancer which has spread from elsewhere to th ...

in rats, although the evidence is scant and generally regarded as evidence that anethole is ''not'' a carcinogen. An evaluation of anethole by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) found its notable

pharmacologic Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemic ...

properties to be reduction in motor activity, lowering of body temperature, and

hypnotic Hypnotic (from Greek ''Hypnos'', sleep), or soporific drugs, commonly known as sleeping pills, are a class of (and umbrella term for) psychoactive drugs whose primary function is to induce sleep (or surgical anesthesiaWhen used in anesthesia ...

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

, and

anticonvulsant Anticonvulsants (also known as antiepileptic drugs or recently as antiseizure drugs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of b ...

effects. A subsequent evaluation by JECFA found some reason for concern regarding carcinogenicity, but there is currently insufficient data to support this. At this time, the JECFA summary of these evaluations is that anethole has "no safety concern at current levels of intake when used as a flavoring agent". In large quantities, anethole is slightly toxic and may act as an irritant.

History

That an oil could be extracted from anise and fennel had been known since the Renaissance by the German alchemist Hieronymus Brunschwig (), the German botanist

Adam Lonicer Adam Lonicer, Adam Lonitzer or Adamus Lonicerus (10 October 1528 – 29 May 1586) was a German botanist, noted for his 1557 revised version of Eucharius Rösslin's herbal. Lonicer was born in Marburg, the son of a theologian and philologist. He ...

(1528–1586), and the German physician Valerius Cordus (1515–1544), among others.See: * * * Anethole was first investigated chemically by the Swiss chemist Nicolas-Théodore de Saussure in 1820. In 1832 the French chemist

Jean Baptiste Dumas Jean Baptiste André Dumas (14 July 180010 April 1884) was a French chemist, best known for his works on organic analysis and synthesis, as well as the determination of atomic weights (relative atomic masses) and molecular weights by measuring v ...

determined that the crystallizable components of anise oil and fennel oil were identical, and he determined anethole's empirical formula. In 1845, the French chemist Charles Gerhardt coined the term ''anethol'' – from the Latin ''anethum'' (anise) + ''oleum'' (oil) – for the fundamental compound from which a family of related compounds was derived. Although the German chemist Emil Erlenmeyer proposed the correct molecular structure for anethole in 1866, it was not until 1872 that the structure was accepted as correct.

References

External links

* {{Estrogenics Flavors Sugar substitutes Essential oils Phenylpropenes O-methylated natural phenols Estrogens