|Jmol-3D images||Image 1|
|Molar mass||148.20 g mol−1|
20-21 °C, 293-294 K, 68-70 °F
234 °C; 81 °C at 2 mmHg
|Related compounds||Anisole; Estragole|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Anethole is an organic compound that is widely used as a flavoring substance. Chemically, it is a phenylpropene, a type of aromatic compound that occurs widely in nature, in essential oils. It contributes a large component of the distinctive flavors of anise and fennel (both in the botanical family Apiaceae), anise myrtle (Myrtaceae), liquorice (Fabaceae), and star anise (Illiciaceae). Closely related to anethole is its isomer estragole, abundant in tarragon (Asteraceae) and basil (Lamiaceae), 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 difference causes certain anise-flavored liqueurs 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.
|Essential oil||World production||trans-anethole|
|Anise||8 tons (1999)||95%|
|Star anise||400 tons (1999), mostly from China||87%|
|Fennel||25 tons (1999), mostly from Spain||70%|
It is distinctly sweet, measuring 13 times sweeter than sugar. It is perceived as being pleasant to the taste even at higher concentrations. It is used in alcoholic drinks Ouzo and Pernod. It is also used in seasoning and confectionery applications, oral hygiene products, and in small quantities in natural berry flavors.
 Precursor to other compounds
Because they metabolize anethole into several aromatic chemical compounds, some bacteria are candidates for use in commercial bioconversion 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).
 Potential uses
 Anti-microbial and anti-fungal activity
Anethole has potent antimicrobial properties, against bacteria, yeast, and fungi. Reported antibacterial properties include both bacteriostatic and bactericidal action against Salmonella enterica but not when used against Salmonella via a fumigation method. Antifungal activity includes increasing the effectiveness of some other phytochemicals (e.g. polygodial) against Saccharomyces cerevisiae and Candida albicans; this synergistic effect has potential medical uses.
In vitro, anethole has antihelmintic action on eggs and larvae of the sheep gastrointestinal nematode Haemonchus contortus. Anethole also has nematicidal activity against the plant nematode Meloidogyne javanica in vitro and in pots of cucumber seedlings.
 Insecticidal activity
Anethole also is a promising insecticide. Several essential oils consisting mostly of anethole have insecticidal action against larvae of the mosquitos Ochlerotatus caspius and Aedes aegypti. In similar manner, anethole itself is effective against the fungus gnat Lycoriella ingenua (Sciaridae) and the mold mite Tyrophagus putrescentiae. Against the mite, anethole is a slightly more effective pesticide than DEET 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. (E)-anethole is highly effective as a fumigant against the cockroach Blattella germanica and against adults of the weevils Sitophilus oryzae, Callosobruchus chinensis and beetle Lasioderma serricorne.
Anethole is responsible for the "ouzo 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 is alleged to have a psychoactive effect. The absence of PMA or any other known psychoactive derivative of anethole leads to the conclusion that any purported psychoactive effect of guarana is not due to anethole. Anethole is also present in absinthe, a liquor with a reputation for psychoactive effects; these effects however are attributed to ethanol. (See also thujone, anethole dithione (ADT), and anethole trithione (ATT)).
Formerly generally recognized as safe (GRAS), after a hiatus anethole was reaffirmed by Flavor and Extract Manufacturers Association (FEMA) as GRAS. The hiatus was due to concerns about liver toxicity and possible carcinogenic activity, reported in rats. Anethole is associated with a slight increase in liver cancer 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 properties to be reduction in motor activity, lowering of body temperature, and hypnotic, analgesic, and anticonvulsant effects. A subsequent evaluation by JECFA found some reason for concern re carcinogenicity but insufficient data. 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.
 See also
- Category:Anise liqueurs and spirits
- List of liqueurs#Anise-flavored liqueurs
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