Linalool
Encyclopedia
Linalool is a naturally occurring terpene
alcohol
chemical found in many flower
s and spice
plants with many commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of spiciness). It has other names such as β-linalool, linalyl alcohol, linaloyl oxide, p-linalool, allo-ocimenol, and 2,6-dimethyl-2,7-octadien-6-ol.
(mints, scented herbs), Lauraceae
(laurels, cinnamon, rosewood), and Rutaceae
(citrus fruits), but also birch trees and other plants, from tropical to boreal climate zones. It has also been found in some fungi.
Both enantiomeric forms are found in nature: S-linalool is found, for example, as a major constituent of the essential oils of coriander (Coriandrum sativum L. family Apiaceae
) seed, palmarosa [Cymbopogon martinii var martinii (Roxb.) Wats., family Poaceae
], and sweet orange (Citrus sinensis Osbeck, family Rutaceae
) flowers. (R)-linalool is present in lavender
(Lavandula officinalis Chaix, family Lamiaceae
), laurel (Laurus nobilis, family Lauraceae
), and sweet basil (Ocimum basilicum, family Lamiaceae
), among others.
Each enantiomer evokes different neural responses in humans, and therefore are classified as possessing distinct scents. 3S-(+)-linalool is perceived as sweet, floral, petitgrain-like (odor threshold 7.4 ppb) and the 3R-form as more woody and lavender
-like (odor threshold 0.8 ppb)
. One common downstream product of linalool is Vitamin E
. In addition, linalool is used by pest professionals as a flea and cockroach insecticide.
Linalool is used in some mosquito repellent products, however the EPA notes that: "A preliminary screen of labels for products containing Linalool (as the sole active ingredient) indicates that efficacy data on file with the Agency may not support certain claims to repel mosquitos."
Akio Nakamura together with colleagues from the University of Tokyo and T. Hasegawa Co., Ltd in Kawasaki, Japan, claim to have demonstrated that inhaling linalool can reduce stress in lab rats. In a study published in The Journal of Agriculture and Food Chemistry, they exposed the animals to stressful conditions and found that those inhaling linalool saw their stress-elevated levels of neutrophils and lymphocytes fall to near-normal levels compared with the controls. Inhaling linalool also reduced the activity of more than 100 genes that "go into overdrive" in stressful situations. The findings could form the basis of new blood tests for identifying fragrances that can soothe stress, the researchers claim.
Terpene
Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium. They are often strong smelling and thus may have had a protective...
alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
chemical found in many flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s and spice
Spice
A spice is a dried seed, fruit, root, bark, or vegetative substance used in nutritionally insignificant quantities as a food additive for flavor, color, or as a preservative that kills harmful bacteria or prevents their growth. It may be used to flavour a dish or to hide other flavours...
plants with many commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of spiciness). It has other names such as β-linalool, linalyl alcohol, linaloyl oxide, p-linalool, allo-ocimenol, and 2,6-dimethyl-2,7-octadien-6-ol.
In nature
Over 200 species of plants produce linalool, mainly from the families LamiaceaeLamiaceae
The mints, taxonomically known as Lamiaceae or Labiatae, are a family of flowering plants. They have traditionally been considered closely related to Verbenaceae, but in the 1990s, phylogenetic studies suggested that many genera classified in Verbenaceae belong instead in Lamiaceae...
(mints, scented herbs), Lauraceae
Lauraceae
The Lauraceae or Laurel family comprises a group of flowering plants included in the order Laurales. The family contains about 55 genera and over 3500, perhaps as many as 4000, species world-wide, mostly from warm or tropical regions, especially Southeast Asia and South America...
(laurels, cinnamon, rosewood), and Rutaceae
Rutaceae
Rutaceae, commonly known as the rue or citrus family, is a family of flowering plants, usually placed in the order Sapindales.Species of the family generally have flowers that divide into four or five parts, usually with strong scents...
(citrus fruits), but also birch trees and other plants, from tropical to boreal climate zones. It has also been found in some fungi.
Enantiomers
Linalool has a stereogenic center at C3 and therefore two stereoisomers: licareol is (R)-(–)-linalool with CAS No. 126–90–9 (PubChem 67179) and coriandrol is (S)-(+)-linalool with CAS No. 126–91–0 (PubChem 13562).Both enantiomeric forms are found in nature: S-linalool is found, for example, as a major constituent of the essential oils of coriander (Coriandrum sativum L. family Apiaceae
Apiaceae
The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
) seed, palmarosa [Cymbopogon martinii var martinii (Roxb.) Wats., family Poaceae
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
], and sweet orange (Citrus sinensis Osbeck, family Rutaceae
Rutaceae
Rutaceae, commonly known as the rue or citrus family, is a family of flowering plants, usually placed in the order Sapindales.Species of the family generally have flowers that divide into four or five parts, usually with strong scents...
) flowers. (R)-linalool is present in lavender
Lavender
The lavenders are a genus of 39 species of flowering plants in the mint family, Lamiaceae. An Old World genus, distributed from Macaronesia across Africa, the Mediterranean, South-West Asia, Arabia, Western Iran and South-East India...
(Lavandula officinalis Chaix, family Lamiaceae
Lamiaceae
The mints, taxonomically known as Lamiaceae or Labiatae, are a family of flowering plants. They have traditionally been considered closely related to Verbenaceae, but in the 1990s, phylogenetic studies suggested that many genera classified in Verbenaceae belong instead in Lamiaceae...
), laurel (Laurus nobilis, family Lauraceae
Lauraceae
The Lauraceae or Laurel family comprises a group of flowering plants included in the order Laurales. The family contains about 55 genera and over 3500, perhaps as many as 4000, species world-wide, mostly from warm or tropical regions, especially Southeast Asia and South America...
), and sweet basil (Ocimum basilicum, family Lamiaceae
Lamiaceae
The mints, taxonomically known as Lamiaceae or Labiatae, are a family of flowering plants. They have traditionally been considered closely related to Verbenaceae, but in the 1990s, phylogenetic studies suggested that many genera classified in Verbenaceae belong instead in Lamiaceae...
), among others.
Each enantiomer evokes different neural responses in humans, and therefore are classified as possessing distinct scents. 3S-(+)-linalool is perceived as sweet, floral, petitgrain-like (odor threshold 7.4 ppb) and the 3R-form as more woody and lavender
Lavender
The lavenders are a genus of 39 species of flowering plants in the mint family, Lamiaceae. An Old World genus, distributed from Macaronesia across Africa, the Mediterranean, South-West Asia, Arabia, Western Iran and South-East India...
-like (odor threshold 0.8 ppb)
Biosynthesis
In higher plants linalool, as other monoterpenoids, is produced from isopentenyl pyrophosphate via the universal isoprenoid intermediate geranyl pyrophosphate, through a class of membrane-bound enzymes named monoterpene synthases. One of these, linalool synthase (LIS), has been reported to produce (S)-linalool in several floral tissues.Uses
Linalool is used as a scent in 60–80% of perfumed hygiene products and cleaning agents including soaps, detergents, shampoos, and lotions. It is also used as a chemical intermediateReagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
. One common downstream product of linalool is Vitamin E
Vitamin E
Vitamin E is used to refer to a group of fat-soluble compounds that include both tocopherols and tocotrienols. There are many different forms of vitamin E, of which γ-tocopherol is the most common in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine and dressings...
. In addition, linalool is used by pest professionals as a flea and cockroach insecticide.
Linalool is used in some mosquito repellent products, however the EPA notes that: "A preliminary screen of labels for products containing Linalool (as the sole active ingredient) indicates that efficacy data on file with the Agency may not support certain claims to repel mosquitos."
Akio Nakamura together with colleagues from the University of Tokyo and T. Hasegawa Co., Ltd in Kawasaki, Japan, claim to have demonstrated that inhaling linalool can reduce stress in lab rats. In a study published in The Journal of Agriculture and Food Chemistry, they exposed the animals to stressful conditions and found that those inhaling linalool saw their stress-elevated levels of neutrophils and lymphocytes fall to near-normal levels compared with the controls. Inhaling linalool also reduced the activity of more than 100 genes that "go into overdrive" in stressful situations. The findings could form the basis of new blood tests for identifying fragrances that can soothe stress, the researchers claim.
List of the plants that contain the chemical
- Cinnamomum tamala
- Ocimum basilicum
- Solidago chilensis Meyen
- Artemisia vulgarisArtemisia vulgarisArtemisia vulgaris is one of several species in the genus Artemisia which have common names that include the word mugwort. This species is also occasionally known as Felon Herb, Chrysanthemum Weed, Wild Wormwood, Old uncle Henry, Sailor's Tobacco, Naughty Man, Old Man or St...
, also known as mugwort
Safety information
Linalool gradually breaks down when in contact with oxygen, forming an oxidized by-product that may cause allergic reactions such as eczema in susceptible individuals. Between 5–7% of patients undergoing patch testing in Sweden were found to be allergic to the oxidized form of linalool. Ways to minimize exposure include not buying large bottles of perfumed hygiene products, and replacing the lid after each use.General references
- Casabianca H, Graff JB, Faugier V, Fleig F, Grenier C (1998) Enantiomeric distribution studies of linalool and linalyl acetate. A powerful tool for authenticity control of essential oils. HRC J High Res Chrom 21:107-112
- Lewinshon E, Schalechet F, Wilkinson J, Matsui K, Tadmor Y, Nam K, Amar O, Lastochkin E, Larkov O, Ravid U, Hiatt W, Gepstein S, Pichersky E (2001) Enhanced levels of the aroma and flavor compound S-linalool by metabolic engineering of the terpenoid pathway in tomato fruits. Plant Physiol 127:1256–1265
- Pengelly, Andrew. The Constituents of Medicinal Plants. 2nd Ed. 2004. CABI Publishing, U.S.A. and UK.
- Raguso RA, Pichersky E (1999) A day in the life of a linalool molecule: chemical communication in a plant-pollinator system. Part 1: linalool biosynthesis in flowering plants. Plant Species Biol 14:95-120
- Akio Nakamura, Satoshi Fujiwara, Ichiro Matsumoto and Keiko Abe. Stress Repression in Restrained Rats by (R)-(−)-Linalool Inhalation and Gene Expression Profiling of Their Whole Blood Cells. J. Agric. Food Chem., 2009, 57 (12), pp 5480–5485.