Farnesol is a natural 15-carbon

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

which is an acyclic

sesquiterpene Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modificat ...

alcohol. Under standard conditions, it is a colorless liquid. It is

hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, t ...

, and thus insoluble in water, but miscible with oils. Farnesol is produced from 5-carbon isoprene compounds in both plants and animals. Phosphate-activated derivatives of farnesol are the building blocks of possibly all acyclic sesquiterpenoids. These compounds are doubled to form 30-carbon

squalene Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...

, which is the precursor for

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

s in plants, animals, and fungi. Farnesol and its derivatives are important starting compounds for natural and artificial

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

Uses

Farnesol is present in many

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 such as citronella,

neroli Neroli oil is an essential oil produced from the blossom of the bitter orange tree (''Citrus aurantium subsp. amara'' or ''Bigaradia''). Its scent is sweet, honeyed and somewhat metallic with green and spicy facets. Orange blossom is also extract ...

cyclamen ''Cyclamen'' ( or ) is a genus of 23 species of perennial flowering plants in the family Primulaceae. ''Cyclamen'' species are native to Europe and the Mediterranean Basin east to the Caucasus and Iran, with one species in Somalia. They gro ...

lemon grass ''Cymbopogon'', also known as lemongrass, barbed wire grass, silky heads, Cochin grass, Malabar grass, oily heads, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family. Some s ...

tuberose ''Agave amica'', formerly ''Polianthes tuberosa'', the tuberose, is a perennial plant in the family Asparagaceae, subfamily Agavoideae, extracts of which are used as a note in perfumery. Now widely grown as an ornamental plant, the species was o ...

rose A rose is either a woody perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be ...

musk Musk (Persian: مشک, ''Mushk'') is a class of aromatic substances commonly used as base notes in perfumery. They include glandular secretions from animals such as the musk deer, numerous plants emitting similar fragrances, and artificial sub ...

balsam Balsam is the resinous exudate (or sap) which forms on certain kinds of trees and shrubs. Balsam (from Latin balsamum "gum of the balsam tree", ultimately from Semitic, Aramaic ''busma'', Arabic ''balsam'' and Hebrew ''basam'', "spice", "perfume ...

, and tolu. It is used in perfumery to emphasize the odors of sweet, floral perfumes. It enhances perfume scent by acting as a co-solvent that regulates the volatility of the odorants. It is especially used in lilac perfumes. Farnesol is a natural pesticide for mites and is a

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

for several other insects. In a 1994 report released by five top cigarette companies, farnesol was listed as one of 599 additives to cigarettes. It is a flavoring ingredient.

Natural source and synthesis

Farnesol is produced from isoprene compounds in both plants and animals. When

geranyl pyrophosphate Geranyl pyrophosphate (GPP), also known as geranyl diphosphate (GDP), is the pyrophosphate ester of the terpenoid geraniol. Its salts are colorless. It is a precursor to many natural products. Occurrence GPP is an intermediate in the isopreno ...

reacts with

isopentenyl pyrophosphate Isopentenyl pyrophosphate (IPP, isopentenyl diphosphate, or IDP) is an isoprenoid precursor. IPP is an intermediate in the classical, HMG-CoA reductase pathway (commonly called the mevalonate pathway) and in the ''non-mevalonate'' MEP pathway of i ...

, the result is the 15-carbon farnesyl pyrophosphate, which is an intermediate in the biosynthesis of sesquiterpenes such as

farnesene The term farnesene refers to a set of six closely related chemical compounds which all are sesquiterpenes. α-Farnesene and β-farnesene are isomers, differing by the location of one double bond. α-Farnesene is 3,7,11-trimethyl-1,3,6,10-dodec ...

. Oxidation can then provide sesquiterpenoids such as farnesol. Farnesylpyrophosphat

In industry, farnesol could be synthesized from

linalool Linalool () refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of ...

History of the name

Farnesol is found in a flower extract with a long history of use in perfumery. The pure substance farnesol was named (c. 1900–1905) after the Farnese acacia tree (''Vachellia farnesiana''), since the flowers from the tree were the commercial source of the floral essence in which the chemical was identified. This particular acacia species, in turn, is named after Cardinal Odoardo Farnese (1573–1626) of the notable Italian Farnese family which (from 1550 though the 17th century) maintained some of the first private European botanical gardens in the

Farnese Gardens The Farnese Gardens ( it, Orti Farnesiani sul Palatino), or "Gardens of Farnese upon the Palatine", are a garden in Rome, central Italy, created in 1550 on the northern portion of Palatine Hill, by Cardinal Alessandro Farnese. They were the fir ...

in Rome. The addition of the -ol ending results from it being chemically an alcohol. The plant itself was brought to the Farnese gardens from the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

and

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

, where it originates.

Cosmetics

Farnesol is used as a

deodorant A deodorant is a substance applied to the body to prevent or mask body odor due to bacterial breakdown of perspiration or vaginal secretions, for example in the armpits, groin, or feet. A subclass of deodorants, called antiperspirants, prevents ...

in cosmetic products. Farnesol is subject to restrictions on its use in perfumery, as some people may become sensitised to it.

Biological function

Farnesol is used by the fungus ''

Candida albicans ''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usu ...

'' as a

quorum sensing In biology, quorum sensing or quorum signalling (QS) is the ability to detect and respond to cell population density by gene regulation. As one example, QS enables bacteria to restrict the expression of specific genes to the high cell densities at ...

molecule that inhibits

filamentation Filamentation is the anomalous growth of certain bacteria, such as ''Escherichia coli'', in which cells continue to elongate but do not divide (no septa formation). The cells that result from elongation without division have multiple chromosomal c ...

Research

Farnesol is studied as a potential treatment for

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

. Farnesol blocks the detrimental effects of

PARIS Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

(a protein that accumulates in the brains of people with Parkinson's) build-up in cells grown in the lab and in mice models.{{Cite web , last=Bailey , first=Suzanne , date=2021-11-08 , title=Farnesol: from perfume to Parkinson's , url=https://cureparkinsons.org.uk/2021/11/farnesol-from-perfume-to-parkinsons/ , access-date=2022-09-11 , website=Cure Parkinson's , language=en-GB

References

Fatty alcohols Alkene derivatives Sesquiterpenes Perfume ingredients Flavors Insect pheromones Primary alcohols