Eucalyptol


Eucalyptol is a natural organic compound that is a colorless liquid. It is a cyclic ether and a monoterpenoid.
Eucalyptol is also known by a variety of synonyms: 1,8-cineol, 1,8-cineole, cajeputol, 1,8-epoxy-p-menthane, 1,8-oxido-p-menthane, eucalyptol, eucalyptole, 1,3,3-trimethyl-2-oxabicyclooctane, cineol, and cineole.
In 1870, F. S. Cloez identified and ascribed the name "eucalyptol" to the dominant portion of Eucalyptus globulus oil.

Composition

The content of eucalyptol is 90% of eucalyptus oil, leading to its name. Wormwood, rosemary, common sage, Cannabis sativa, and other aromatic plant foliage contain eucalyptol. Eucalyptol may be toxic if ingested.

Properties

Eucalyptol has a fresh mint-like smell and a spicy, cooling taste. It is insoluble in water, but miscible with ether, ethanol, and chloroform. The boiling point is 176°C and the flash point is 49°C. Eucalyptol forms crystalline adducts with hydrohalic acids, o-cresol, resorcinol, and phosphoric acid. Formation of these adducts is useful for purification.

Uses

Flavoring and fragrance

Because of its pleasant, spicy aroma and taste, eucalyptol is used in flavorings, fragrances, and cosmetics. Cineole-based eucalyptus oil is used as a flavouring at low levels in various products, including baked goods, confectionery, meat products, and beverages. In a 1994 report released by five top cigarette companies, eucalyptol was listed as one of the 599 additives to cigarettes. It is claimed to be added to improve the flavor.
Eucalyptol is an ingredient in commercial mouthwashes, and has been used in traditional medicine as a cough suppressant.

Insecticide and repellent

Eucalyptol is used as an insecticide and insect repellent.
In contrast, eucalyptol is one of many compounds that are attractive to males of various species of orchid bees, which gather the chemical to synthesize pheromones; it is commonly used as bait to attract and collect these bees for study. One such study with Euglossa imperialis, a nonsocial orchid bee species, has shown that the presence of cineole elevates territorial behavior and specifically attracts the male bees. It was even observed that these males would periodically leave their territories to forage for chemicals such as cineole, thought to be important for attracting and mating with females, to synthesize pheromones.

Toxicology

In higher-than-normal doses, eucalyptol is hazardous via ingestion, skin contact, or inhalation. It can have acute health effects on behavior, the respiratory tract, and the nervous system. The acute oral is 2480 mg/kg. It is classified as a reproductive toxin for females and a suspected reproductive toxin for males.

Pharmacodynamics

It is known that eucalyptol has anti-inflammatory properties and researchers have suggested these, and other effects such as soothing sensations, may be mediated by the ion channel TRPM8. The same channel is also activated by menthol.

List of plants that contain the chemical

N.B. Listed as "cineole" in some pharmacopoeias.